Document MGrKo8ZnZ2m1p1y7p0BdX3qDx

Il A001194 > o o <X> US00006656 DEPARTMENT OF THE NAVY naval research laboratory 4555 OVERLOOK AVE SW WASHINGTON DC 30375-6320 IN H C f l T R f r t R TO : 3905 From: Commanding Officer, Naval Research Laboratory To: Commander, Naval Air Systems Command (Code 4.3.T Sinwell) Subj: STATUS REPORT ON THE DEVELOPMENT OF AN ENVIRONMENTALLY IMPROVED AFFF Enel: (1) Two copies of subject report 1. Enclosure (1) is forwarded for your information. This work was accomplished under Naval Air Systems Task 2221 -J19. 2. Aqueous film-forming foam (AFFF) is the most effective foam agent for combating two dimensional fuel spill fires. The Naval Air Systems Command (NAVAIR) relies on AFFF systems to protect its assets. The current formulation of AFFF concentrates includes compounds which are nonbiodegradable and which have potential toxic impact to the environment. There are different approaches for developing an environmentally improved suppression agent. This report outlines die feasibility of formulating an environmentally benign AFFF, the current direction and status of R&D and technical risks and probabilities of success for different approaches. Recommendations for continued development of an environmentally improved AFFF are proposed, including the development of a fire suppression model. 3. The point of contact at the Navy Technology Center for Safety and Survivability (Code 6180) is Dr Frederick W Williams (202) 767-2476; email, Copy to: COMNAVAIRSYSCOM (Code 4.3.5 Holman) COMNAVSEASYSCOM (03G2 Darwin) NAVFAC (J. E. Gott) NAVFAC/ESC (R. Lee) NAVFAC/LANT (K. Clark) TYNDALL AFB (WL/FIVC Vickers) US00006657 6180/0060A. 1:FWW 14 February 1997 Subj: STATUS REPORT ON THE DEVELOPMENT OF AN ENVIRONMENTALLY IMPROVED AFFF BACKGROUND The U.S. Navy is one of the world's largest consumers of aqueous film-forming foam (AFFF). AFFF is the agent of choice for suppressing two-dimensional combustible/flammable liquid fuel fires resulting from aviation and shipboard accidents and battle induced damage. The Naval Air Systems Command (NAVAIR) uses AFFF in essential fire suppression systems protecting aircraft assets. Mobile vehicles (both shipboard and shoreside) use AFFF which is discharged through turrets and handlines. Aircraft carrier flight deck washdown systems can discharge AFFF in the event of a serious flight deck mishap. The importance of AFFF to the Navy is evident by the rapid control, cooling, and extinguishment times required when accidents involve weapons. When exposed to fire, weapons may "cook-off" and explode in as little as 60 seconds. The control of any weapons exposure fire on air-capable ships is reliant on the suppression capability of AFFF. AFFF systems have been specifically designed to control and suppress flight deck fires to reduce the chance of weapons cook-off [1,2]. Any reduction in AFFF performance would result in substantially increased risks of catastrophic shipboard fires. The role of AFFF in protecting Naval assets should not be underestimated. NAVAIR is by no means the sole Navy user of AFFF. The Naval Sea Systems Command (NAVSEA), the technical manager for the AFFF procurement specification, MILF-24385 [3], specifies AFFF to protect surface ship and submarine machinery spaces through handlines and fixed sprinkler systems. Deluge sprinkler systems are used to protect aircraft carrier hangar decks. The Naval Facilities Command (NAVFAC) specifies AFFF sprinklers for shoreside hangars and other flammable liquid hazards. The formulation of foam concentrates currently requires the use of nonbiodegradable materials and chemicals which may have toxicological effects. There is now heightened awareness of the impact of these materials. As a result of recently enacted Federal environmental legislation and specific local waste treatment issues, there is a need to evaluate foam in terms of environmental impact. Environmental issues which have been raised include persistence of AFFF fluorosurfactants, discharge of glycols used in foam formulations, and the potential for upsetting the balance of biodegradation mechanisms in wastewater treatment facilities when foams are discharged and treated in this manner. These issues affect training of Enel (1) to NRL Ltr Ser 3905 6180/0060 US00006658 Navy personnel, discharge testing of foam from flight deck fixed and mobile systems, and the installation of fixed foam systems, for example, in hangars. Environmental issues associated with AFFF have and will continue to impact NAVAIR specifically and the Navy in general. For example, the new P-25 flight deck firefighting vehicle was proposed to have a 3780 L (1000 gal) premix tank of AFFF. For maintenance and testing, the tank contents must be discharged. Environmental restrictions limit the ability to discharge the premix solution overboard. As a result, a less reliable and more maintenance intensive proportioning system is being considered instead of the premix tank. Environmental concerns also limit the ability to test and maintain the flight deck AFFF washdown system. At shoreside facilities, NAVFAC must now consider the disposition of effluent from AFFF system discharges resulting from testing, maintenance, and accidental trips of the system. Other military users, notably the U.S. Air Force, have also encountered environmental concerns with AFFF. They have sponsored research currently geared primarily toward the elimination of glycol ethers from AFFF formulations. The Navy continues to act in a leadership role in the development, analysis, and specification of AFFF. Navy representatives participate in a National Fire Protection Association (NFPA) Task Group to evaluate AFFF environmental issues. The prominence of the AFFF MIL SPEC has recently been broadened to include the national and international commercial aviation sectors by its adoption in NFPA Standard 403, "Aircraft Rescue and Fire Fighting" [4], AFFF is widely recognized as the most effective foam agent for suppressing hydrocarbon pool fires. When mixed with water, the resulting solution achieves surface and interfacial tension characteristics needed to produce a film which will spread across a hydrocarbon fuel. The foam produced from this agent extinguishes fires by halting fuel vaporization in the same fashion as other foams (e.g., protein or fluoroprotein foam). However, the foam has film formation capabilities and is a very fluid foam that rapidly spreads across the fuel surface. The compounds used to create the desired film formation characteristics of AFFF do not readily breakdown in the environment. Thus, the very elements which make AFFF an effective agent have a potentially detrimental impact on the environment. OBJECTIVE The objective of this status report is to outline the feasibility of formulating an environmentally benign AFFF. The current direction and status of R&D is described. Technical risks and probabilities of success are assessed. Recommendations for continued development of an environmentally improved AFFF are proposed. 2 US00006659 ISSUES AND SCOPE AFFF is discharged to combat fires, suppress vapors resulting from a spill, train firefighters, and test/maintain fire suppression systems. AFFF may also be inadvertently discharged as a result of a false trip of a fixed system. In each of these situations, there are potential mitigating strategies. For example, a "training foam" might be used as a surrogate for actual AFFF for training scenarios. Likewise, simulants or plain water could potentially be used for system discharge testing or maintenance. For firefighting, an agent with less environmental impact could be used. This could take the form of an existing agent, e.g., fluoroprotein or protein foams. Alternately, a new, environmentally benign agent could be developed. Fluoroprotein foams may not contain glycol esters, but still contain fluorosurfactants. The fluorosurfactant persistence issue would not be solved. A protein foam might be used, but at a great sacrifice to extinguishment performance, e.g., 50 percent increase in extinguishment time compared to AFFF. Given the additional requirement to change out equipment to be air-aspirating, the fallback to protein-based foams is not a practical approach. No commercially available foam has been found to be as effective as AFFF [5], For NAVAIR, it is undesirable to introduce a separate, "surrogate" agent for testing and training. For example, crash firefighting and rescue (CFR) vehicles used in a training scenario are often in a standby mode for an actual incident. The unit would respond in the event of an aircraft incident. The introduction of a less effective AFFF training surrogate would eliminate the vehicle from its active "standby" status. The introduction of such an agent also increases the risk of misuse of the agent in an actual fire, i.e., through failure to flush and refill the concentrate tank with genuine AFFF. The development of a new firefighting agent, an environmentally benign foam, offers the most attractive solution for NAVAIR. While it is the most technically challenging, it offers the optimum long-term answer to the environmental issue. This report focuses on the feasibility of developing such an agent. ENVIRONMENTAL ISSUES The discussion of potential approaches to developing an acceptable AFFF should be made in the context of the environmental issues. Scheffey [6] outlined foam environmental considerations, which are summarized here. Quantitative data and methods to evaluate environmental impact are not widely published or well developed. The issue is not a new or unique development, but has received increased notice as a result of increased attention to environmental impact of firefighting agents. Factors related to the impact of firefighting foam on the environment include the following: 3 US00006660  Discharge of foam solutions and fuel-contaminated foam solutions to waterways and the potential toxicity to aquatic life; Effects on water treatment facilities; and Persistence and biodegradability of chemicals in foam concentrates and solutions including potential toxicity to humans. In order to assess the impact of foam on the environment, the likely scenarios under which AFFF may be discharged should be considered. Based on these scenarios, the overall impact can be assessed and, where appropriate, potential mitigation strategies can then be developed. Likely scenarios include uncontrolled fire situations, potential hazardous situations, firefighting training evolutions, and fixed or mobile vehicle suppression system discharge testing (including intentional and accidental). Biodegradability The primary component of AFFF solution is water. Other components include nonfluorinated surfactants (e.g., hydrocarbon surfactants), glycol ethers, and fluorinated surfactants. The fluorinated surfactants are particularly resistant to biodegradation. Conversely, the less effective protein-based foams were largely assumed to be non-polluting because of their "natural" organic base. An early review of the available literature by Factory Mutual [7] indicated that both types of agents present inherent environmental issues and that effluents containing either should be processed in some form of sewage treatment facility or diluted prior to discharge into a stream. A conventional method used to determine the biodegradability of a material is comparison of the Chemical Oxygen Demand (COD) of the material with its Biological Oxygen Demand (BOD). This is particularly important for waste treatment facilities where the stability of the treatment process may be upset. A compilation of test methods is found in "Standard Methods for the Examination of Water and Wastewater [8]." The BOD measures the amount of oxygen consumed by microorganisms in breaking down a hydrocarbon. The COD measures the maximum amount of oxygen that could theoretically be consumed by microorganisms. Therefore, a BOD/COD ratio is representative of the ability of the microorganism to biodegrade the components in a foam. The higher the BOD/COD ratio, the more biodegradable the foam. Results reported for BOD/COD of AFFF range from 0.60 to 0.99. The U.S. Military Specification requires a maximum COD of 500,000 mg/L and a minimum 20-day BOD/COD ratio of 0.65 for 6 percent concentrate. AFFF agents have been reported to have higher BOD and COD values than protein foams [9]. AFFF solutions are high BOD materials compared to the normal influent to treatment plants. Large quantities can "shock load" wastewater treatment facilities. 4 US00006661 The fluorochemical based surfactants in AFFF have a carbon-fluorine chain that apparently does not break down in either the BOD or the COD test. If the rest of the hydrocarbons in the AFFF that are consumed in the COD are also consumed in the BOD then the BOD/COD ratio would be one. The AFFF would appear to be completely biodegradable, even though the remnant carbon-fluorine chain would remain. If non-biodegradability concerns are based on the persistence of the fluorochemical surfactants, then the environmental impact tests currently used to assess foams do not address this concern. There is speculation that the undegradated material is biologically inert, but there are no published data to confirm this. Foaming and Emulsification of Fuels The surfactants in AFFF solutions can cause foaming in treatment aeration ponds. This foaming process may suspend high BOD solids in the foam. If these are carried over to the outfall of the treatment facility, nutrient loading in the outfall waterway may result. Foam aeration may also cause foam bubble backup in sewer lines. In uncontrolled fires, spills, and live fire training scenarios, foams may contain suspended fuels. The fuel may become emulsified in the foam water solution. Toxicity In sufficient concentrations, foams may affect aquatic life. A number of fish toxicity studies have been performed. In tests using fathead minnows, the U.S. Air Force found that these fish could live in a simulated effluent stream containing 250 ppm (V/V) AFFF without fatality for up to eight days. LC50values at 96 and 24 hours were 398 and 650 ppm, respectively [9]. The U.S. MIL SPEC requires AFFF toxicity testing in accordance with ASTM E-729 using dynamic procedures with the Killiefish. An LC50of 1000 mg/L for 6 percent concentrate is permitted. By themselves, these values may be considered as having a low degree of fish toxicity using environmental regulation rating scales. Localized concentrations in ponds or streams may exceed the values cited if there is no water movement. There are no published data on the phytotoxicity of foam solutions, but there have been no published reports of plant kills resulting from foam solution discharges. Manufacturers report that thermal decomposition products from AFFF do not present a health hazard during firefighting. Again, there are no data published in the literature. Manufacturers' product environmental data for AFFF include references to a test where a layer of AFFF was burned in a pan of gasoline inside an enclosure. Two measurements of HF recorded above the sample were 0.23 and 0.16 ppm [10]. 5 US00006662 Current Regulatory Environment Glycol Ethers As a result of the 1990 Clean Air Act, the U.S. Environmental Protection Agency now requires the reporting of certain chemical uses and releases. Among these, glycol ethers are subject to reporting under Section 313 of the Emergency Planning and Community Right-toKnow (EPCRA) list. Additionally, the glycol ether category was placed on the list of hazardous air pollutants (HAP) under the 1990 Clean Air Act amendments. The HAP listing results in the designation of the chemical as a "hazardous substance" under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). The inclusion of glycol ethers on the HAP list had automatically set a default reportable quantity requirement of one pound per day for CERCLA reporting. This resulted in the requirement to report every time one pound of glycol ether entered the environment in a twenty-four hour period. For AFFF, this equated to a discharges as low as 15 gallons of solution (not concentrate). The EPA has since revised the reporting requirement (June 12, 1995, final rule 60 CFR 30926). Currently there is no reportable quantity for the glycol ethers. Thus, foams containing glycol ethers are not subject to EPA reporting. Summarizing, the trend at this time includes an effort by industry to permit greater amounts of agent which could be discharged before they become reportable. Continued use of the glycol ethers in the longer term may be problematic if future EPA toxicological analysis suggest continued or greater restrictions on this product. Fluorosurfactants To date, no regulations related to the reporting or restriction of fluorosurfactants have been identified. There is concern in the industry that these elements will eventually be targeted for regulation by virtue of their persistence in the environment. Toxicity effects have not been well established, and there are difficulties in detecting fluorosurfactant elements in waste systems. The elimination of fluorosurfactants as a general class of elements available for use in fire extinguishing agents would have a significant effect. For example, reliance on nonfluorosurfactant foam, e.g., protein foam, would reduce fire extinguishment effectiveness by a factor of roughly 2:1 [11]* Critical Navy systems, e.g., aircraft carrier flight deck washdown systems, are currently not readily adaptable to protein foams, which require air-aspiration. Wastewater Treatment Plants Effluent from AFFF streams may ultimately be processed through wastewater treatment plants. Problems may result from large quantity discharge of AFFF to these facilities. 6 Foaming at the plant can cause suspension of high biological oxygen demand (BOD) solids in the foam. This may upset the treatment facility balance and cause nutrient loading at the outfall of the treatment plant. Because AFFF solutions are high BOD materials, they can cause wastewater treatment plant "shock loading" or overload. Bacteria used in plants may also be killed by shock loading. As a result of these factors, treatment plants may operate outside nutrient and water quality permit limits regulated by local environmental agencies. In extreme cases, local authorities may severely restrict or prohibit the discharge of AFFF into the local wastewater stream. This is currently the case with the Hampton Roads Sanitation District (HRSD), located adjacent to the Norfolk Naval Station. Treatment plant upsets have reportedly occurred as a result of fire training facility AFFF use and AFFF system discharge tests from aircraft carriers. Requirements for wastewater limits to treatment plants may include BOD, COD, pH, oil, and grease, total suspended solids, and a measurement of surfactant quantity. These parameters are described in the Military Handbookfor Firefighting School Facilities, MIL-HDBK-1027/1. APPROACH TO THE DEVELOPMENT OF ENVIRONMENTALLY FRIENDLY AFFF Two fundamental approaches have been proposed to develop a new AFFF. One approach is to identify alternative chemicals and formulate novel foam concentrates. These novel foam concentrates would first be screened to see if they form a positive spreading coefficient. They may also be fire tested at a relatively small scale. This approach assumes that a positive spreading coefficient on a hydrocarbon fuel is necessary for a candidate agent to have similar if not equal fire extinguishment and bumback performance to AFFF. The alternative approach assumes that chemical derivatives are not readily available or identifiable which combine both desirable firefighting and environmental characteristics. The contention is that a lack of fundamental theoretical understanding of foam spreading and extinguishment mechanisms limits the ability to investigate novel concepts/formulations. This approach relies on the development of a foam spreading and extinguishment model to predict foam performance. Small-scale apparatus might be used in support of this model. Having verified the extinguishment model, approaches which provide the required physiochemical properties could be investigated. This could lead to an approach which does not rely on the surface-tension reduction characteristics (for which fluorosurfactant chemicals are vital). This report will discuss the known work in this area (limited in both cases), the pros and cons of each approach, technical risks, and the ultimate payoff. 7 US00006664 INVESTIGATION OF CHEMICAL ALTERNATIVES The direct investigation of chemical alternatives offers the potential to reduce or eliminate two of the chemicals which do or could be considered to have an environmental impact: glycol ethers and fluorosurfactants. The known work in this area is reviewed here. The primary sources of information are vendor information, chemical and fire test data from the Naval Research Laboratory and Hughes Associates, Inc., and preliminary data from work conducted by the U.S. Air Force. Elimination of Glycol Ethers Vendor Information Discussions with vendors supplying MIL SPEC AFFF on the Qualified Products Lists [12] have informally indicated that alternatives may exist for the glycol ethers used in AFFF. In the near term, the use of reduced quantities of glycol ethers appears to be technically feasible. One vendor has successfully tested a MIL SPEC agent with less glycol ether. The new compound reduced the glycol ether content from 30 percent by volume to 20 percent. Understandably, these vendors, for proprietary reasons, are hesitant to discuss specific chemical formulations. The market place, particularly customer requirements for Material Safety Data Sheets (MSDS) will require partial if not full disclosure of the alternative formulations. Based on this information alone, the reduction of glycol ethers in AFFF formulations appears to be feasible and of low-to-moderate technical risk. This is supported by experimental data by NRL as described in the next section. The technical feasibility of the total elimination of glycol ether in the near-to-mid term is subject to debate. Some vendors indicate that this may not be possible, particularly to the extent that the one pound reportable quantity level can be met. Others indicate that they are nearly ready to submit a glycol ether free MIL SPEC agent. NRL and Hughes Associates Data A one-quarter scale fire test apparatus was created to evaluate novel foam formulations. This was a 1 m2 (7 ft2) circular test pan with nozzles and foaming apparatus to control foam expansion and solution flow and pressure. Surface tension measurements were performed with surfactants obtained from different manufacturers. Organosilicon and fluorosurfactant combinations were evaluated. Although the nonionic organosilicon and nonionic fluorosurfactant chemicals provided the requisite surface tension reduction, their formulations did not foam. However, an anionic and cationic fluorosurfactant combination, which provided the lowest surface tensions, showed fire knockdown characteristics in small-scale test evaluations. From Table 1, it can be seen that, with less volume of chemicals, comparable bumback and extinguishment times were achieved. For example, average concentrations for the novel formulations was 2.6-2.9 percent in distilled and hard tap water (see Table 2). The tests indicate that the expansion ratio of the air to liquid volume was obtained without the 8 US00006665 ? refractive index modifier, butyl carbitol, which is present at 15 percent concentration in 3M- These data suggest that agents with reduced concentrations of glycol ethers or with replacement ethers are technically feasible. The exact chemicals used would have to be compared against the chemicals on the CERCLA reporting requirements listing. There areX technical challenges to overcomell since butyl carbitol is used as a refractive index modified and for freeze protection in non-MIL .SPECfagentiT TheTefractive index is used for field testing of AFFF proportioning systems. The current refractive index Table 1. Fire Performance Characteristics of AFFF and Novel Foam Agents _____________ Using a 1 m2 (7 ft2) Small-scale Test Platform_____________ Agent Application Rate (Lpm/m3 fsnm/fPVi 100% Extinguishment Time 00 Extinguishment Density (L/m2 fral/fF Bumback Times (s) 25% 50% 3M MIL SPEC 6% AFFF (Lot #159, 6/90) Batch #1 DuPont/3M Fluorosurfactants 1.7(0.041) 1.5 (0.036) 2.4 (0.058) 2.2 (0.055) 2.4 (0.060) 2.5 (0.062) 2.0 (0.048) 3.2 (0.079) 3.1 (0.077) 3.1 (0.075) 39 52 41 39 39 36 35 40 39 67 1.1 (0.027) 476 506 1.3 (0.031) 490 519 1.6 (0.040) 428 467 1.5 (0.036) 453 495 1.6(0.039) 411 468 1.5 (0.037) 416 466 1.1 (0.028) 761 810 2.1 (0.052) 510 530 2.0 (0.050) 571 586 3.4 (0.084) 452 477 Batch t t l DuPont/3M Fluorosurfactants 3.1 (0.075) 3.1 (0.075) 94 DNE1 4.8(0.118) 467 486 -- ---- Batch #5 DuPont/3M Fluorosurfactants 3.1 (0.077) 3.1 (0.077) 57 DNE1 3.0 (0.073) 446 470 ---- 'DNE did not extinguish. 9 US00006666 Table 2. Contents of Anionic - Cationic Fluorosurfactant Agent in 20 Liters Manufacturer/Product Surfactant Type Percent by Volume 3M / FC-135 DuPont / FEA Mona Industries / ADA Stepan Company / Maprosyl 3 Union Carbide / Polyox Aldrich / STG Cationic: Perfluoroalkyl quaternary ammonium iodide Anionic: Lithium (fluoroalkyl) thio propionate Amphoteric: Cocamidopropyl betaine Anionic: Sodium lauroyl sarcosinate Nonionic: 5% poloxyethylene, triethyleneglycol monomethylether 0.31 0.20 0.31 0.63 0.49 measurement techniques are dependent on sufficient quantities of butyl carbitol in the L concentrate^Altemative benign solvents or compounds may provide the requisite refractive index modification. For example, urea may be added to a formulation for refractive index modification. Alternatively, the electrical conductivity method might be used for field testing of AFFF proportioning systems [13]. However, electrical conductivity measurements are non linear in seawater solutions. Application of this method for Navy shipboard situations is questionable. /s' U.S. Air Force Information The U.S. Air Force, in current work to reduce the environmental impact of AFFF, has proposed formulations for a revised MIL SPEC [14]. These formulations are to include "solvents not on Hazardous Air Pollutant List of the 1990 Clean Air Act nor subject to SARA Title 11, Section 313 regulations." This suggests that Air Force researchers believe that replacement solvents are technically feasible, but no specific agents, formulations, or test data have been reported. It has been proposed that the refractive index will be lower for a modified agent compared to MIL SPEC agents. Again, no specific data have been reported. Elimination of Fluorosurfactants Vendor Information No QPL vendor has, to date, indicated that fluorosurfactants can be reduced or eliminated from MIL SPEC AFFF. Market and regulatory forces play at least a partial role in this issue. On one hand, there are no regulations or requirements to eliminate fluorosurfactants. On the other hand, the vendors appear to understand that, by virtue of its persistence, fluorosurfactants may potentially be regulated. Vendors have indicated that the AFFF market is very competitive. Since the fluorosurfactants are one of the most expensive components of AFFF, this suggests that the levels of fluorosurfactants are already at a 10 US00006667 minimum. If an alternative was readily available, it probably would already have been proposed for use. It is unlikely that such a replacement chemical is readily available. One vendor has stated that no other known class of material has the capability of producing solutions of sufficiently low surface tension to permit the formulation of an aqueous film on hydrocarbon fuels. At least one manufacturer of fluorosurfactant compounds has initiated a research program to develop a "biodegradable" fluorosurfactant. NRL and Hughes Associates Data A review of potential candidate chemicals based on their physical performance criteria is summarized in an SBIR Phase I report on environmentally friendly AFFF prepared by Hughes Associates, Inc. for the U.S. Air Force [15]. Previous patents were consulted for information on chemical components and their behavior as extinguishing agents. One group of surfactant chemicals was the organosilicons. Most of the organosilicon chemicals produced commercially are used in polymer, paint and textile processing, and enhanced oil recovery. As such, most of these organosilicon compounds, manufactured by Dow Coming and Union Carbide, are derived from polydimethysiloxanes and are too viscous for foams. However, patent information revealed that there existed some siloxanes with charged functional groups that foam at low concentrations. In fact, one company, Union Carbide, claimed to have invented cationic, anionic, and amphoteric siloxane surfactants that extinguished hydrocarbon fires. Coincidentally, these inventions occurred just after the original patent for extinguishing hydrocarbon fires using fluorosurfactants was issued to researchers from NRL [16]. Another potential avenue for rvaluation is the synergistic behavior of fluorosurfactant and organic surfactants. When the decrease in surface tension of a mixture of anionic and cationic fluorosurfactants together was found to be lower than each separately, new formulations were investigated to demonstrate this phenomena [17]. Fluorosurfactants were obtained from DuPont and Minnesota Mining and Manufacturing (3M) for this purpose. Next, in the process of choosing chemicals to use for interfacial tension reduction, a stable but biodegradable, non-toxic group of surfactant chemicals was chosen for their ability to foam and enhance the spreading of non-hydrocarbon surfactants over the hydrocarbon fuel surface. A range of manufacturers sent samples to Hughes Associates, Inc., including, Stepan, Co., Shell, Rohm and Haas, Rhone Poulenc, Mona Industries, BASF, Dow, and Union Carbide Corp. The foamers contain ingredients that are used for cosmetic type applications. Their stability in a high temperature type situation depends on the stabilizers used to strengthen the bubble lamellae. For this purpose nonionics were employed of low molecular weight with low vapor pressure ethers of chain length similar to the surfactant foamer. For instance, a typical foamer of eleven carbons, lauryl sulfate, was matched with methoxy triglycol using polyethyleneoxide as the foam stabilizer. 11 US00006668 The surfactant formulations were evaluated on the basis of surface tension for their ability to attain low surface tensions separately and as synergistic combinations. The surfactant combinations of Table 3 from Reference 15 are examples of the method used for novel agent formulation. The choice of surfactant concentration was based on the critical micelle concentration of the surfactant. This is the point where the surface tension changes very little as one increases the concentration in the solution. Preliminary fire testing of the novel agents using the 1 m2 small-scale fire test apparatus showed that none of the organosilicon compounds worked as extinguishing agents. As noted earlier, their surface tension reduction is comparable to the fluorosurfactant surface tension reduction in water at similar concentrations. However, these foams, when applied to a fire, were destroyed. Different fluorosurfactant combinations were successfully created which could extinguish the fire. Applications of theoretical assumptions from research and texts to new and old surfactant technology provided products with interesting results. For example, a cationic-anionic blend of fluorosurfactants showed lower surface tension than either one by itself. This indicates that, besides increased surface pressure and spreading capability on hydrocarbon surfaces, there is similarity to their behavior with hydrocarbon surfactants. It was shown that cationic organic ammonium bromides displayed lower surface tensions with an anionic fluorosurfactant, i.e., surface tensions lower than each exhibit separately [18]. It was also well documented that amphoteric and anionic fluorosurfactant blends worked well together. The problem with this approach is that amphoteric fluorosurfactants were used at much greater than necessary concentrations. They were being used in combination with anionic organic interfacial tension reducers as well as with the anionic fluorosurfactant moiety [19]. It was concluded that an organic amphoteric surfactant mixed with anionic fluorosurfactant and anionic organic surfactant mixed with a cationic fluorosurfactant performed as an extinguishing agent. Because the organic-fluorosurfactant combinations synergistically reduce surface tensions to lower values at lower concentrations of all components involved, it may be possible to use less fluorosurfactant to achieve similar results. The data to date do not support the use of a nonfluorinated surfactant to achieve the desired surface tension reduction properties. U.S. Air Force Information The U.S. Air Force has sponsored a Phase II SBIR project with the goal of chemically developing an environmentally friendly AFFF. The research proposes three levels of AFFF performance as shown in Table 4 [14], The proposal implies that the fluorine content can be reduced, but not eliminated. This is consistent with the NRL/Hughes Associates findings. The proposed level of decrease in fluorine content is not identified. No decrease in 12 US00006669 US00006670 Surfactant Chemical FSA (DuPont) Lithium 3-[(lH,lH,2H,2H -Fluoroalleyl) thio] propionate FSA (DuPont) (UC) L7607-Polyalkylene oxide polydimethylsiloxane FC-135 (3M) 1 - Propanaminium 3 [[[(heptadecafluoroctyl) sulfonyl] amino] N N -trimethyl] FC-135 (3M) FSA (DuPont) FC-135 (3M) FSA - DuPont Silwet-L7607-Union Carbide FC-135 (3M) FSA (DuPont) L7607 (Union Carbide) Pluronic-Polyoxyethylene (propylene) (BASF) - copolymer MTG (Aldrich) Ethanol, (2-(2-(2-methoxy-ethoxy)etboxy) - Table 3. Example Surface Tension Measurements o f Novel Agents [16] Charge Anionic Apparent Surface Tension y(dynes cm'1) 17.75 Concentration ( %in deionized distilled H ,0 0.01 Anionic nonionic Cationic 20 16.8 l 0.2 0.01 Cationic Anionic Cationic Anionic Nonionic Cationic Anionic Nonionic Nonionic Nonionic 15.85 16 16 13 0.2 0.3 0.38 firefighting performance is proposed while a goal of improved bumback performance has been established. Table 4. Fire Performance Parameters Proposed for the USAF Environmentally Improved AFFF Agents [141 3% AFFF-EMB Parameters Type A 3% AFFF-EMB Type B 3% AFFF-EMB Type C 3% AFFF-EMB MIL-F-24385F 3% AFFF Fluorine content limited to Environmental impact improvement Bumback resistance improvement low level very much limited med. level much much max. 1% limited very much not limited ,__ -- 28 ft2 fire - Foam application time to extinguish, seconds, maximum Half strength Full strength 5 x strength Bumback time o f resulting foam cover, seconds, minimum Half strength Full strength 5 x strength 45 (3/4) MIL-F MIL-F 300 (3/4) 360 240 MIL-F MIL-F MIL-F MIL-F 420 300 MIL-F MIL-F MIL-F 360 480 360 45 30 55 300 360 200 50 fit2 fire - Foam application time to extinguish, seconds, maximum Bumback time o f resulting foam cover, seconds, minimum 40 second summation MIL-F 360 320 MIL-F 420 340 MIL-F 460 360 50 360 320 The Air Force also found that commercially available agents which may exhibit improved biodegradable characteristics (BOD/COD ratios), e.g., protein or fluoroprotein foams, were not as effective as MIL SPEC AFFF in terms of fire extinguishment and bumback resistance. This is consistent with previous NRL and Hughes Associates studies which showed MIL SPEC AFFF to be the most effective Class B firefighting foam currently available [5,15,20]. Summary The limitations of the "chemical approach" for developing improved agents have been identified. Glycol ether content may be totally or substantially reduced; the total elimination of these solvents appears to be a moderate technical risk. The total elimination of fluorosurfactants does not appear to be technically feasible, at least in the near term. The 14 US00006671 fluorosurfactants provide the necessary surface tension reduction of solutions to create a positive spreading coefficient on hydrocarbon fuels. Yet, research and evaluation of test data by NRL and Hughes Associates indicate that there is no direct correlation between spreading coefficient and fire extinguishment/bumback resistance of firefighting foams [5]. There is a lack of correlation between chemical/physical properties typically measured for foams and fire performance. This limitation impedes the evaluation of novel concepts, elements, and chemical formulations since the required suppression theory has not been fully developed. FOAM SUPPRESSION MODELING The mechanisms of foam fire extinguishment on two-dimensional pool fires have not been completely elucidated. Usually, the fire extinguishment is described simply as a factor of the cessation of fuel vaporization at the fuel surface. As the fuel vapor decreases, the size of the combustion zone decreases. When the area is totally covered, extinguishment occurs. Hanauska et al. [15] have proposed fundamental extinguishment parameters, summarized below. Foam Loss Mechanisms Fire extinguishment by foams can be summarized as shown in Figure 1. Foam having a temperature, T:, and depth, h, spreads at a rate of V5along a fuel of temperature, T,, and vapor pressure, Pv. Fuel is volatized by the fire at a rate of rh ^ , which is a function of the radiative feedback, q,,d. The foam is added by the discharge application, rhadd, and lost through evaporation, mvlip, and drop through, mdrop. The total mass loss of the foam is a function of the loss due to drop through and the mass loss due to evaporation. The mass loss due to drop through is at least partially dependent on the drainage of liquid from the foam. Evaporation of the liquid occurs primarily from radiant energy from the fire. Assuming that most of the radiation results in direct evaporation of the foam, the evaporation of foam can be characterized by menv a p Qevap 7T V (1) where AHVis the combined latent and sensible heat of vaporization. Using a rough estimate of q" from large pool fires of 45-185 kW/m2 yields an evaporation rate of 18-72 g/m2s assuming a heat of vaporization of 2563 kJ/kg. To account for reflective and absorbed losses, Persson [22] has proposed a calculation method: . // ,H m' Vap = 1< .rad (2) 15 Air Fig. 1 - Param eters affecting foam fire extinguishm ent [16] 16 US00006673 where 1^ is an experimentally derived constant using different fluxes from a radiant exposure. For q " ^ values of 45 and 185 kW/m2, equation 2 yields values for l ii " ^ of 11 and 46 g/m2s, respectively. The estimated m"eviipbased on equation 1 at the same heat fluxes were 18 and 72 g/m2/s. The mass loss rates from the experimental results are about 62 percent lower than the theoretical loss. The difference between values is attributable to neglecting the reflected and absorbed losses in equation 1. This indicates that about 48 percent of the radiant flux to the foam surface is either reflected from or absorbed into the foam blanket. The division between these two heat transfer mechanisms is not clear and is an area for further study. Foam loss can likewise be described theoretically based on the downward force of gravity and the opposing forces due to surface tension and buoyancy. Alternatively, a model from mass loss due to drainage can be expressed as a time-averaged constant: ^drain ~ Kl (3) where kd is an experimentally determined drainage coefficient. From the data of Persson, the drainage coefficient can be estimated to be 17 to 25 g/s/m2. The drainage rate was found to be relatively independent of the radiant heat flux to the foam, but highly dependent on the expansion ratio. Foams with lower expansion ratios will drain faster. For example, decreasing the expansion ratio by about half (11.3 to 5.3) increased the drainage rate by a factor of about 2 (55 to 105 g/min). Decreasing the expansion ratio changes fundamental parameters of the foam, which allows it to drain faster. Foam Spread Over Liquid Fuels In order to predict the extinguishment of a liquid pool fire by firefighting foam, it is necessary to describe the process of spreading the foam over the liquid fuel surface. This process of foam spread on a liquid fuel is similar to the spread of a less dense liquid (such as oil) on a more dense liquid (such as water). This phenomenological approach to the spread of foam on a liquid pool is appropriate to the extent that foam can be treated as a liquid. Kraynick [22] characterizes foams macroscopically as being Bingham fluids with a finite shear stress and a non-Newtonian viscosity. That is, foam displays an infinite viscosity up to some initial shear rate above which they display a shear rate dependent viscosity. Since fuels typically have low viscosities (especially compared to foam viscosities at relatively low shear rates), it may be appropriate to model foam spread across a fuel surface using models developed for oil spread on water. These models assume that the oil spreads as a fluid with a viscosity much larger than the water on which it is spreading. The process of oil spread on water has been described in detail by Fay [23], and Fay and Hoult [24]. Their phenomenologically based model describes three regimes of spread as characterized by combinations of spreading forces and retarding forces. The first regime is the gravity-inertia regime where the outward spread of the oil is driven by a gravity force and retarded by the 17 US00006674 inertia required to accelerate the oil. The second regime is the gravity-viscous regime, where the gravity-induced spreading is retarded by viscous dissipation in the water. Since the oil is much more viscous than the water, they assume that there is slug flow in the oil and that the viscous drag force is dominated by the velocity gradient in the water. The final regime is characterized by a surface tension spreading force opposed by the viscous retarding force. By setting the spreading and retarding forces equal in each of the regimes, they developed equations to estimate the length of the spread as a function of time. By treating the spread of foam on fuel as similar to the spread of oil on water, the equations developed by Fay and Hoult might be used to describe the spread of a foam blanket over a fuel pool as a function of time. Since foam generally has a much higher viscosity than the fuel on which it is spreading, the assumption of slug flow made for the oil by Fay and Hoult should be reasonably valid for foam spread on fuel as well. The equations are g r a v i t y - i n e r t i a r e g i m e : l = (AgV f2)1'4 gravity - viscous regime: l .Ag V 22t 3/2 1/6 , 1/2 (4) surface tension-viscous regime o2t 3 1/4 p2V where 1 = length of spread (cm), A ( P fuel ~ Pfoam )/pfuel' g = acceleration of gravity (981 cm/s2), V = foam volume (cm3), t = time (s), V = kinematic viscosity of fuel (cm2/s), o = spreading coefficient (dynes/cm), and p = density of fuel or foam (g/cm). Equation (4) represents an untested theoretical model of foam spread. The equation includes the parameters which are known or suspected to affect foam spread. 18 US00006675 Prediction of Foam Spread Persson and Dahlberg [25], working independently from U.S. researchers, developed a foam spread prediction model using the same "oil on water" theory used by Hanauska et al. [15]. Viscous friction, described as a friction constant or friction factor, is assumed to be the dominant mechanism in opposing foam spread. The spreading process is decoupled from mass transport due to evaporation and drainage of water contained in the foam. Preliminary experiments with foam spreading on a 20 m diameter circular pan of water were used to determine the friction coefficient. The model fits reasonably well with the experimental results for a wide range of volume flow rates and foam expansion numbers as shown in Figures 2 and 3. This work constitutes the first step in an attempt to develop a model describing foam spread on a burning surface. Modeling of Fire Extinguishment At this point, modeling of foam extinguishment cannot be performed because of the large number of remaining uncertainties. A model would have to take into account the addition of foam to the fuel surface, the spread of foam on the fuel surface, and the foam loss mechanisms of evaporation and drop through. The foam spread length equations can be used to estimate the area of foam coverage at a specific time and for a specific quantity of foam. Modeling at this time is now limited because of the lack of established values for ke (Equation 2) and kd (Equation 3). Also, the yield stress and viscosity relationships for firefighting foams have not been quantified. Preliminary modeling of fire extinguishment has been performed using assumed fire heat fluxes and spreading factors [15]. The modeling used the MIL SPEC 2.6 m2 (28 ft2) fire pan and application rate. The model predicted extinguishment on the order of 6 seconds. Tests with MIL SPEC AFFF generally have extinguishment times on the order of 25 seconds, with a maximum of 30 seconds permitted. Modeling with larger fire areas also predicts critical application rates of approximately one-half of the critical rates based on actual data. The model is overpredicting the speed of foam spread, but the results are encouraging given the level of assumptions now being used. Experimental work is clearly needed, particularly in the area of foam breakdown as a function of radiant heat flux from a pool fire. It is anticipated that bench-scale test apparatus can be constructed to develop foam loss factors. Combined with more precise spreading friction factors, the modeling of foam fire extinguishment appears to be technically feasible. Advantages in Developing Foam Suppression Theory Preliminary work by both the Navy and Air Force demonstrate the difficulties in developing nonfluorosurfactant compounds and glycol ether-free mixtures. The lack of correlation between spreading coefficient data and fire test results also indicates a lack of 19 US00006676 E co Tch a> E CoO Fig. 2 - Comparison between predicted and measured extension for detergent foam having a friction factor of 0.1 N/m3 (from R ef 25) 20 US00006677 10 Fig. 3 * Comparison between predicted and measured extension for AFFF having a friction factor of 0 .1 N/m3 ( f r a n Ref 25) 21 US00006678 fundamental understanding of foam suppression mechanisms. In order to generate the next generation of foam agents, i.e., environmentally benign, new approaches/techniques will probably be required. These concepts might be derived from outside the traditional fire suppression chemical field, e.g., from the coatings technology field. To apply techniques/mixtures/approaches from other disciplines, fundamental scientific relationships must be in place. These relationships would be established through the development of a foam fire extinguishment model. In the near term, this modeling combined with bench-scale, correlatable test methods could be used to evaluate novel formulations to address environmental issues. In the longer term, advanced fire suppression agents, with perhaps double the extinguishment effectiveness of currently available AFFF, could be evaluated at a substantially reduced cost and effort compared to current approaches. Even if efforts to improve the environmental characteristics fall short of goals, a successfully developed and validated fire extinguishment model would still be useful for general foam evaluation. This would represent a significant advance in the technology which is now reliant on moderate- to full-scale fire testing. CONCLUSIONS 1. AFFF is a vital component for the protection of Naval aviation assets. This protection, particularly as it applies to weapons cook-off, requires an agent with rapid control, cooling, and suppression capability. Reduction of fire suppression capability through the use of existing, environmentally more favorable agents would increase the risk of catastrophic fires and probably require significant hardware modifications to accommodate the agent. 2. Regulations related to the discharge of chemicals in AFFF require reporting for relatively small amounts of solution. The trend is toward more strict regulation of the chemicals in AFFF and of the discharge of AFFF into the environment. 3. There are several potential options to address issues related to AFFF impact on the environment. The best option for the long term is to develop an agent that is totally biodegradable. 4. It appears to be technically feasible to reduce the quantities of chemicals which exert an impact on the environment. It is not clear that these elements can be totally eliminated in near-term reformulations of AFFF. 5. Suppression mechanisms of hydrocarbon pool fires by foam are not fully understood. This inhibits the investigation of alternative approaches to developing an environmentally benign AFFF. 22 US00006679 6. It appears to be technically feasible to develop a fire suppression model which could be used to assess alternative methods for developing an environmentally friendly agent. This model could form the basis for the development of the next generation foam agent. RECOMMENDATIONS 1. Continue to monitor the trends of regulations affecting the discharge of AFFF. 2. Continue to monitor the near-term development of any AFFF reformulations which reduce the amount of non-biodegradable or regulated compounds in AFFF. 3. Adopt the approach of developing a long-term solution which would address all aspects of the environmental issue, i.e., a next generation biodegradable fire suppression agent. 4. Develop the fire suppression model which would be used to support the formulation of the next generation agent. A work plan for the development of the fire suppression model is included in Appendix A. REFERENCES 1. Carhart, H.W., Leonard, J.T., Darwin, R.L., Bums, R.E., Hughes, J.T., and Jablonski, E.J. "Aircraft Carrier Flight Deck Fire Fighting Tactics and Equipment Evaluation Tests," NRL Memorandum Report 5952, February 1987. 2. Scheffey, J.L., Darwin, R.L. and Leonard, J.T., "Improved Fire Protection for Flight Deck Weapons Staging Area (Bomb Farm), NRL Memorandum Report 5917, January 1987. 3. Military Specification, "Fire Extinguishing Agent, Aqueous Film-forming Foam (AFFF) Liquid Concentrate, for Fresh and Seawater," MIL-F-24385F, 7 January 1992. 4. National Fire Protection Association Standard 403, "Standard for Aircraft Rescue and Fire Fighting Services at Airports," National Fire Protection Association, Quincy, MA, 1993. 5. Scheffey, J.L., Darwin, R.L., Leonard, J.T., Fulper, C.R., Ouellette, R.J., and Siegmann, C.W., "A Comparative Analysis of Film Forming Fluoroprotein Foam (FFFP) and Aqueous Film Forming Foam (AFFF) for Aircraft Rescue and Fire Fighting Services," Hughes Associates, Inc. Report 2108-A01-90 for the NFPA Aviation Committee, June 1990. 23 US00006680 6. Scheffey, J.L., "Foam Agents and AFFF Design Considerations, "The SFPE Handbook o f Fire Protection Engineering," Second Edition, National Fire Protection Association, Quincy, MA (in press). 7. Krasner, L.M., D.E. Breen, and P.M. Fitzgerald, "Fire Protection of Large Air Force Hangars," Factory Mutual Research Corporation, Norwood, MA, October 1975. 8. American Public Health Association, "Standard Methods for the Examination of Water and Waste Water," 18th Edition, Washington, DC, 1992. 9. National Environmental Health Laboratory, "Biological Treatment of Fire Fighting Foam Waste," Report No. REHL(K) 67-14, U.S.A.F., Kelly AFB, TX, September 1967. 10. 3M Company, "Light Water Brand AFFF Waste Disposal Recommendations and Hazard Evaluation," 3M Product Environmental Data Sheet, St. Paul, MN, February 19, 1991. 11. Geyer, G.B., L.M. Neri, and C.H. Urban, "Comparative Evaluation of Fire Fighting Foam Agents," Federal Aviation Administration Report FAA-RD-79-61, Washington, DC, August 1979. 12. Department of the Navy, "Qualified Products List of Products Qualified under Military Specification MIL-F-24385 Fire Extinguishing Agent, Aqueous Film Forming Foam (AFFF) Liquid Concentrate, for Fresh and Sea Water," Naval Sea Systems Command QPL-24385-25, Washington, DC, 21 May 1992. 13. Timms, G., and P. Haggar, "Foam Concentration Measurement Techniques," Fire Technology, 26 (1), February 1990, pp. 41-50. 14. United States Air Force, "AFFF Interagency Working Group Meeting," Wright Laboratories/FIVCF, Panama City, FL, brief presented at the Naval Sea Systems Command, 8 September 1994. 15. Hanauska, C.P., J.L. Scheffey, R.J. Roby, and D.T. Gottuk, "Improved Formulations of Firefighting Agents for Hydrocarbon Fuel Fires," SBIR Phase I Final Report for the U.S. Air Force, Hughes Associates, Inc., Columbia, MD, 1994. 16. Tuve, R.L., and Jablonski, E.J., (1966), U.S. Patent 3,258,423: "Method of Extinguishing Liquid Hydrocarbon Fires," U.S.A., June 28, 1966. 17. Scamehom, J.F., ed., Phenomena in Mixed Surfactants, University of Oklahoma, ACS Symposium Series No. 311, Washington, DC, 1986, pp. 10. 24 US00006681 18. Zhao, G.X., and Zhu, B.Y., (1986), "Surface Absorption and Micellization of the Mixed Soludon of Fluorocarbon and Hydrocarbon Surfactants, in Phenomena in Mixed Surfactants, Scamehom, J.F., ed., ACS Symposium Series No. 311, Washington, DC, 1986, pp. 184-198. 19. Falk, R.A., (1977), U.S. Patent 4,042,522, "Aqueous Wetting and Film Forming Composition," Ciba-Geigy Corporation, Ardsley, NY, August 16, 1977, pp. 3. 20. Scheffey, J.L., Wright, J., and Sarkos, C., "Analysis of Test Criteria for Specifying Foam Firefighting Agents for Aircraft Rescue and Firefighting," FAA Technical Report (in preparation). 21. Persson, H., "Fire Extinguishing Foams-Resistance Against Heat Radiation," Brandforsk project 609-903, SR Report 1992:54, Swedish National Testing and Research Institute, Sweden, 1992. 22. Kraynik, A.M., "Foam Flows," Annual Review o f Fluid Mechanisms, 20, 1988, pp. 325-357. 23. Fay, J.A ., "The Spread of Oil Slicks on a Calm Sea," Oil on the Sea, (D. Hoult, ed.), Plenum, NY, 1964, pp. 53-64. 24. Fay, J.A ., and D.P. Hoult, "Physical Processes in the Spread of Oil on a Water Surface," Coast Guard Final Report, Contract DOT-CG-01, 381-A, Project No. 714107/A/001, Department of Mechanical Engineering, Massachusetts Institute of Technology, 1971. 25. Persson, B., and Dahlberg, M., "A Simple Model for Predicting Foam Spread Over Liquids," paper presented at the Fourth International Symposium on Fire Safety Science, Ottawa, Canada, June 12-17, 1994 (proceedings in publication). J. ^ Hughes Associates, Inc. Baltimore MD R. E. Bums Hughes Associates, Inc. Baltimore MD C. P. Hanauska Hughes Associates, Inc. Director Navy Technology Center for Safety & Survivability 25 US00006682 Appendix A W ork Plan to Develop a Fire Suppression Model A-l US00006683 Task 1 Task 2 Task 3 Task 4 Task 5 Task 6 Task 7 Task 8 Task 9 Task 10 Work Plan to Develop a Fire Suppression Model Refine the fire extinguishment model developed in previous efforts. Write computer-based agent performance program to execute calculations. Develop as a baseline the fire extinguishment model. Consider other modeling parameters such as three-dimensional fires and bumback resistance. Construct bench-scale apparatus. This would include apparatus for critical foam thickness and foam loss mechanisms. Conduct experiments with existing formulations. Construct small-scale foam spread apparatus. Conduct experiments with existing formulations. Use results to modify agent performance program as required. Correlate results with larger scale spreading data. From the agent performance program of Task 1 and data generated in Tasks 2 and 3, calculate the extinguishment capabilities of foams and compare to existing test data. Propose new formulation work based on the parameters that will improve performance and biodegradability of agents. Define biodegradation and environmental issues related to firefighting foam and surfactants. Select or develop appropriate test methods and criteria. From information learned in Tasks 4 and 5, select various surfactants and chemicals to evaluate in new formulations. Acquire these surfactants and chemicals from chemical manufacturers. Formulate new firefighting foams and examine performance with the bench-scale and foam spreading apparatus. Evaluate the performance of the agents from Task 7 with the agent performance program. Test foam formulations that performed favorably in Tasks 7 and 8 using a 28 ft2 MIL SPEC test at NRL CBD. Define the most promising formulations. Perform large-scale fire tests as appropriate. A-2 US00006684 DEPARTMENT OF THE NAVY NAVAL RESEARCH LABORATORY 4555 OVERLOOK AVE SW WASHINGTON DC 20375-5320 IN R C P I.V R E F E R T O 3901 Ser 6180/0048 From: Commanding Officer, Naval Research Laboratory To: Commander, Naval Facilities Engineering Service Center (Code ESC 421 R. Lee), 560 Center Drive, Port Hueneme CA 93043 Subj: OPTIMIZATION OF THE AFFF SEPARATOR DESIGN Enel: (1) Two copies of subject report 1. Enclosure (1) is forwarded for your information. 2. This report provides an outline test plan to conceptualize the trailer-mounted separator unit. This work, including the investigation of one surrogate foam agent, can be performed with the existing budget. Additional surrogate agents can be evaluated at an estimated cost of $3K per agent. 3. The NRL point of contact is Dr. Frederick W. Williams, Code 6180, (202) 767-2476, email: fwilliams@itd.nrl.navy.mil. Copy to: COMNAVSEASYSCOM (Code 03G Darwin) NFEC (Gott) NAVFAC/LANTDIV (Code 18111 Clark) US00006685 6180/0048A.1:FWW 28 January 1997 Subj: OPTIMIZATION OF THE AFFF SEPARATOR DESIGN Ref: (a) (b) Beitel, J.J., Bums, R.E., Ouellette, R., Szepesi, D., Leonard, J.T., and Williams, F.W., "Tests for Mechanical Separation of AFFF in Firefighting Wastewater," NRL Ltr Rpt Ser 6180/0620, 01 Nov 96. Williams, F.W., and Beitel, J.J., "Separation Yields for Mechanical Separation of AFFF in Firefighting Wastewater," NRL Ltr Rpt Ser 6180/0603, 11 Oct 96 1. Introduction - Prior work has demonstrated the potential for a mechanical separator that can remove AFFF from a water solution (references (a) and (b)). The objective of the initial scale-up of this work is to conceptualize a trailer mounted processing system that can process --1,000 gallons (-3780 L) of AFFF solution in a 24-hour period. Limitations of the existing data were identified and discussed in a 25 November 1996 program review meeting. In order to provide final design parameters to overcome these limitations, a series of tests is proposed. This letter report outlines the proposed testing. 2. Objective - The objective of this work is twofold and entails the following tasks: Task 1 - Provide data of surface tension and drain time versus concentration for surrogate foam agents. Task 2 - Provide final design basis information for a trailer mounted process system. This process system should be capable of processing 1,000 gallons (3780 L) of AFFF/water solution in a 24-hour period. 3. Task 1 - Surrogate Foam Information. The work in this task will be to develop the following correlations: Surface tension versus concentration, Drain time versus concentration, and Surface tension versus drain time. This work will be performed on one or more surrogate AFFF foam agents as specified by NAVFAC/LANTDIV. Enel (1) to NRL Ltr 3901 Ser 6180/0048 US00006686 The work will be performed AT NRL's Chesapeake Bay Detachment. The work will entail the following: Making solutions (15 - 20) of various concentrations, Performing surface tension measurements on each concentration using the du Nouy tensiometer, Performing drain time measurements on each concentration using the procedure developed in the earlier work, and Data correlation and processing. The deliverable for this task will be graphical correlations for the surrogate agent(s). 4. Task 2 - Final Design Data. This work will encompass experiments in which several design variables will be studied. As noted in the earlier work, the processing time will be dependent on the size of the processing tank, the depth of the solution in the tank, and air flow/distribution. These variables will be evaluated with the goal of determining the best process parameters to be used in the design of the trailer mounted processor. The tests will be conducted at NRL's Chesapeake Bay Detachment. The tests will use the Large Tank (Apparatus #4) (reference (a)) and an existing, large "bilge pan." The tests (except for one) will be conducted using a 3% solution of AFFF. This concentration was selected since it represents the highest potential concentration of AFFF in the waste stream. The endpoint for the tests will be the attainment of an 8 second drain time for the solution. This drain time represents a low level of fluorosurfactant remaining in the solution. The tests to be conducted are described in Table 1. Test No. 1 2 3 4 5 6 7 Apparatus Large Tank Large Tank Large Tank Large Tank Large Tank Large Tank Bilge Tank Table 1. Test Matrix Surface Area (ft2( m2)) Depth (in. (cm)) 12(1.1) 18(46) 24 (2.2) 18(46) 24 (2.2) 36 (91) 24 (2.2) 18(46) 24 (2.2) 18 or 36 (46 or 91) 24 (2.2) 18 or 36 (46 or 91) 100 (9.3) 12 (30) Other Use 6% AFFF Additional Air Piping Additional Air Flow 2 This test matrix will provide the following information: Tests 1 and 2 will provide information concerning the processing rate of the same percent solution but with different surface areas. For this test, the large tank will have to be divided using a plexiglass insert; Tests 2 and 3 will be used to determine if the depth of the solution results in any significant time savings with regard to processing time; Tests 2 and 4 will be used to compare the two types of AFFF concentrate and determine if a significant difference exists between them; Tests 2 and 5 will provide information concerning the use of additional bubbles (i.e., same air flow rate but additional tubing) and their impact on processing times. The depth to be used will be determined based on Tests 2 and 3; Tests 2 and 6 will provide information concerning the impact of additional air flow (higher air flow rate) on the processing time. The need for this test may be reassessed based on the results of Test 5. The depth to be used will be determined based on Tests 2 and 3; and Test 7 will entail the use of the existing "bilge tank" currently available at CBD. It is proposed that one-half of tank (-100 ft2(9.3 m2)) will be used, A piping system will be installed and a test conducted. This test will provide data that, along with the data from Tests 1 and 2, will assist in the selection of the overall size of the processing tank that will be required. During these tests, the drain time of the solution will be monitored and reported. Also, during Tests 2 and 4, samples will be obtained so that surface tension measurements can also be made. These measurements will provide a verification of the previous work. The results of the experiments along with the proposed design parameters will be provided in a final letter report. Based on these tests, a better understanding of the various parameters can be established, and these data can then be applied to the final design of the trailer mounted processing system. 3 US00006688 5. Timing - It is anticipated that the tests and the report can be completed within three months after the initiation of the work. JESSE J.BEITEL Senior Scientist Hughes Associates, Inc. Baltimore, MD 35 DANIEL B. SZEPESI Engineer Hughes Associates, Inc. Baltimore, MD FREDERICK W. WILLIAMS Director, Navy Technology Center for Safety & Survivability NRL Code 6180 4 US00006689 DEPARTMENT OF THE NAVY NAVAL RESEARCH LABORATORY 4555 OVERLOOK AVE SW WASHINGTON DC 20375-5320 n NCPI.V ncren t o : 3905 Ser 6180/0572 B 7 SEP 1996 From: Commanding Officer, Naval Research Laboratory To: Commander, Naval Facilities Engineering Service Center (Code ESC-421 R Lee), 560 Center Drive, Port Hueneme CA 93043-4327 Subj: ENVIRONMENTAL AND EFFICACY TESTS FOR AFFF SEPARATOR USING ACTUAL FIREFIGHTING WASTEWATERS Enel: (1) Two copies of subject report 1. Enclosure (1) is forwarded for your information and retention. This work is being conducted under PE DBOF, Work Request N6830596WX00024. 2. There is concern about the potential environmental harm when Aqueous Film Forming Foam (AFFF) constituents spread to the environment or are discharged to waste water treatment plants. NRL has developed a prototype AFFF separator. The AFFF separator reduces the AFFF surfactants from typical firefighting waste waters. The presence of contaminants that would typically be found in firefighting wastes, such as petroleum hydrocarbons and aromatic compounds, do not appear to adversely affect the mechanism or the efficiency of the process. In addition, the separator reduces the other pollutants in the waste as measured by BOD5, COD, VPH, BTEX and TPH. The concomitant reduction can be significant, e.g., 95 to 100%, particularly for the more volatile species. The overall results are extremely encouraging and continued development of the AFFF separator is recommended. 3. The NRL Point of Contact is Dr. F, W. Williams, Code 6180, (202) 767-2002; email, fwilliams@itd.nrl.navy.mil. For furher information about the Navy Technology Center for Safety and Survivability visit the NRL WEB Site at http//chemdiv-www,nrl.navy.mil/6180.him. Copy to: COMNAVSEASYSCOM (Code 03G Darwin) NFEC (Gott) LANTDIV/NAVFAC (Code 18111 Clark) US00006690 6180/0572A. 1:FWW 24 September 1996 Environmental and Efficacy Tests for AFFF Separator using Actual Firefighting Wastewaters J^P^Leonard F.W. Williams Navy Technology Center for Safety and Survivability Naval Research Laboratory D P. Verdonik R.E. Bums R.J. Ouellette Hughes Associates, Inc. 3610 Commerce Drive, Suite 817 Baltimore, MD 21227-1652 Enel (1) to NRL Ltr 3905 Ser 6180/0572 US00006691 vO 'O CONTENTS Page 1.0 INTRODUCTION.............................................................................................................. 1 1.1 Review of Previous W ork....................................................................................... 2 1.2 Environmental Requirements .................................................................................3 2.0 APPROACH...................................................................................................................... 3 3.0 EXPERIMENTAL..............................................................................................................4 3.1 Source of Firefighting Test W aters........................................................................ 4 3.1.1 MILSPEC Test W ater.................................................................................4 3.1.2 Waste Tank Water ..................................................................................... 5 3.2 AFFF Surfactant Separation................................................................................... 5 3.3 Environmental T ests............................................................................................... 5 4.0 RESULTS AND DISCUSSION . 4.1 AFFF Surfactant Reduction 4.2 Environmental T ests........ 4.3 MBAS and Drain Time Correlation ................................................................. 11 4.4 Summary .............................................................................................................. 13 5.0 CONCLUSION................................................................................................................ 13 7.0 REFERENCES .................................................................................................................14 US00006692 Environmental and Efficacy Tests for AFFF Separator Using Actual Firefighting Wastewaters 1.0 INTRODUCTION The U.S. Navy is one of the world's largest consumers of aqueous film-forming foam (AFFF), AFFF is currently the agent of choice for suppressing combustible/flammable liquid fuel fires resulting from aviation and shipboard accidents and battle induced damage. The Naval Air Systems Command (NAVAIR) uses AFFF in essential fire suppression systems protecting aircraft assets. Mobile vehicles (both shipboard and shore side) use AFFF which is discharged through turrets and hand lines. Aircraft carrier flight deck wash down systems can discharge / AFFF in the event of a serious flight deck mishap. Lr td s NAVAIR is not the sole Navy user of AFFF. The Naval Sea Systems Command, the technical manager for the AFFF procurement specification, MIL-F-24385 [1], specifies AFFF to protect surface ship and submarine machinery spaces through hand lines and fixed sprinkler \ systems. Deluge sprinkler systems are used to protect aircraft carrier hangar decks. The Naval Facilities Command (NAVFAC) specifies AFFF sprinklers for shore side hangars and other flammable liquid hazards. In addition, AFFF is used by the U.S. Air Force and the civil sector for aircraft crash, fire and rescue, and in hanger applications. There is concern about the potential environmental harm when the AFFF constituents spread to the environment with run-off from fire fighting operations or are discharged to wastewater treatment plants [2]. The primary component of AFFF solution is water. Other components include non-fluorinated surfactants (e.g., hydrocarbon surfactants), glycol ethers, and fluorinated surfactants. The environmental issues which have been raised include persistence of AFFF fluorosurfactants, discharge of glycol ethers used in foam formulations, and the potential for upsetting the balance of biodegradation mechanisms in wastewater treatment facilities when foams are discharged and treated in this manner. It is suspected that some of the compounds used to create the highly effective characteristics of AFFF do not readily breakdown in the environment. Thus, the very elements which apparently make AFFF an effective agent have a detrimental, or at least an unknown, impact on the environment. Based on these perceived problems, local authorities may severely restrict or prohibit the discharge of AFFF into the local wastewater stream. This is currently the case with several wastewater treatment plants in the Maryland/Virginia area. 1 US00006693 1.1 Review of Previous Work an economical way to separate AFFF from the wastewater at fire training facilities. The project resulted in a proof-of-principle device that lowered the AFFF in water solutions [3], A brief summary of that work follows. The first task was to develop a simple test that could be performed in the field that would correlate with the AFFF concentration. The method developed is based on drain times. The AFFF MILSPEC requires that drain time be determined for all AFFF solutions [1]. The drain time is defined as the amount of time required for a specific amount of generated foam to return to a specific amount of liquid. The MILSPEC test required specific procedures and equipment that was not readily adaptable to a small-scale field test. An inexpensive test to measure drain time was developed. Drain time is measured using a 2.54 cm(l-in) diameter by 10.2 cm(4 in) high test tube with a screw cap. The tube is filled with 5.2 cm(2 in) of solution and shaken 50 times. The time to reduce 90 percent of the foam back to liquid is recorded. Several problems still exist with this manual method: sensitivity to how vigorously the sample is shaken, the temperature and the amount of liquid. To overcome some of these problems a single operator was used. Acceptable repeatability was then achieved. The drain time results were correlated against a property of the AFFF that could be accurately measured, surface tension. The results were in excellent agreement and provide a good measure of the relative decrease in the amount of AFFF in the solution. This proof-ofprinciple work only used one AFFF concentrate, 3M brand 6% MILSPEC AFFF foam concentrate (FC-206 CF). With a method to measure the relative concentration of AFFF in solution, a series of breadboard AFFF separators were developed. The basic design concept was to use air bubbles to create a foam. Water alone can not form a bubble, but the surfactants in the AFFF allow a foam to form. The foanT3houHT5^cPir^ with the average water solution. This effectively concentrates the surfactants into the foam which can be subsequently removed by mechanical means. .The method was shown to be capable of separating the surfactants trorh AFFF-water solutions down to a concentration of 1000 ppm, or lower, of surfactants. In summary, previous development work proved 1) the feasibility for using foam creation to concentrate and remove the AFFF fluorosurfactants, 2) the basic design features for the separator unit, and 3) a simple field test that correlates the reduction in surfactant levels to a laboratory measurement technique. All of these results, however, were obtained on `standard' or pure AFFF-water solutions that would be typical from AFFF discharge tests, e.g., testing fire trucks. There are two other scenarios for creating wastewater containing AFFF that still needed to be evaluated in the separator unit: Standardized Fire Tests (e g., AFFF MILSPEC Qualification Tests) Actual Fire events (Firefighter Training) 2 US00006694 1.2 Environmental Requirements In addition to the other types of wastewaters, the effluent from the separator needed to be evaluated in terms of environmental impacts. Seven tests were chosen based on requirements of Hampton Road Sanitation District and the wastewater treatment plant at the Chesapeake Beach Detachment (CBD) of the Naval Research Laboratory (NRL) [4,5]: 1- Biological (Biochemical) Oxygen Demand, 5 day (BODs) 2. Chemical Oxygen Demand (COD). 3. Volatile Petroleum Hydrocarbons (VPH) 4. Total Petroleum Hydrocarbons (TPH) 5. Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) 6. Methylene Blue Active Substances (MBAS) 7. pH The BOD test measures the amount of dissolved oxygen that is consumed by bacteria in breaking down the organics present in the sample. The higher the BOD the greater the extent of pollution. The COD test measures the amount of oxygen that is required to oxidize the organics present under certain conditions of oxidizing agent, temperature and time. It is a separate measure from the BOD test and has no direct relationship to the results of the BOD test [5,6], The ratio of BOD to COD however, is often used as an indication of the degree of biodegradability of a sample. A BOD/COD ratio equal to one means that all of the organics that can be oxidized, as indicated by the COD test, are oxidized by the microbes in the water, as indicated by the BOD test. The petroleum hydrocarbon content is tested in three ways. The BTEX test is exactly as its name implies. It measure the concentration of benzene, toluene, ethylbenzene and xylenes. The VPH test covers the organic range C4 through C l2, commonly referred to as the gasoline range. The BTEX and gasoline range tests can be run together. The TPH tests measures organics CIO and up. This effectively covers the diesel range (CIO to C24) and the oil and grease range. These three tests in combination, should adequately characterize the fuel concentration/contamination of the wastewater [6], The MBAS test is used to measure the concentration of detergents and surfactant type materials that react with methylene blue to form a blue colored salt. It is only applicable to anionic surfactants measured as linear alkyd sulfonates (LAS) [5], 2.0 APPROACH Wastewater from a standard AFFF QPL test, and from the 660,0001 (20,000 gal) wastewater tanks at CBD were tested using the AFFF separator to determine the ability to reduce 3 US00006695 the AFFF surfactants. The drain time versus concentration plots developed under the previous work were used to determine the effectiveness of the separator with these wastewaters [3], Before and after samples of the two wastewaters were sent to an EPA approved environmental laboratory for the required tests. All samples were tested for BOD, COD, pH, MBAS, BTEX, and VPH. Only the wastewater from the storage tanks was tested for TPH. The wastewater from the QPL test uses gasoline so there should not be any heavy hydrocarbons present that would require the TPH tests. Standard samples of AFFF-water solution were prepared for 1000 ppm, 500, ppm, 100 ppm and 10 ppm. These `standards' were sent to the same environmental laboratory to undergo MBAS tests to determine how well the MBAS results compare with the drain time results. 3.0 EXPERIMENTAL 3.1 Source of Firefighting Test Waters The test waters came from the live-fire facilities at the CBD. The complex consists of office, laboratory, and indoor and outdoor fire testing spaces. All of the live-fire testing facilities use potable water, generally from the fire hydrant system, and are designed to collect and store all resulting wastewater. There are three basic scenarios for fire tests run at CBD that result in wastewater: Qualified Purchase List (QPL) test for Aqueous Film Forming Foam (AFFF), as described by MIL-F-24385[1,7] Small-scale tests performedin Burn Building. Mid-scale and large-scale tests performed on the flight simulation outdoor fire mat or other outdoor fire test areas. 3.1.1 MILSPEC Test Water The waste from the QPL fire tests is the easiest to characterize because there is a specific standard test method. The purpose of this test is to determine if the specific product meets the requirements for AFFF listed in the MILSPEC. The resulting waste, hereafter referred to as MILSPEC TEST will contain gasoline and AFFF, and may also contain products from the fire. The fire products of concern are the aromatic hydrocarbons such as those measured by the BTEX test. The AFFF concentrates and, therefore, the resulting solutions used in these tests will contain fluorinated surfactants, hydrocarbon surfactants, and glycol ethers. The precise make-up of each AFFF concentrate is proprietary and will vary from vendor to vendor. The QPL test requires using salt water to simulate the effects of using ocean water. The waste may also contain the salts used to generate the artificial sea water. 4 US00006696 3.1.2 Waste Tank Water The two waste tanks collect all of the effluents from the three types of testing: QPL Tests, Small-scale tests in the Burn Building, and Medium- and Full-scale Tests. The resulting waste, hereafter referred as WASTEWATER can contain any or all of the constituents used: heptane, JP-5, JP-4, Diesel, AVGAS, MOGAS, fire combustion products, MILSPEC and non-MILSPEC AFFF, CLASS A foam extinguishing agents, PKP and salt (used to simulate sea water). There is no way to predict the concentrations of the various elements. Samples taken at different times may result in considerably different composition depending upon the fire testing that is taking place at any given time. 3.2 AFFF Surfactant Separation A MILSPEC TEST was performed using Angus MILSPEC 3% foam. Instead of discharging the effluent to the waste collection system it was collected in a 209 1(55 gal) drum. The drum was turned on its side and let stand for seven days. Approximately 57 1(15 gal) was drained from the bottom of the tank and placed into the 35.6 cm(14 in) by 35.6 cm (14 in) by 91.4cm(36 in) high separator unit. Air was supplied at an initial rate of 1132 1/hr (40 SCFH) and the foam was removed every five minutes. The air flow rate was increased to 2264 1/min (80 SCFM) when the drain time dropped to approximately 1.5 seconds to further reduce the surfactant concentration. The test was stopped when the drain time dropped below one second, approximately 5 hours and 40 minutes from beginning of test. In a second test 761 (20 gal) of WASTEWATER was removed from the CBD storage tanks and placed into the separator unit. A sump pump with a two stage water filter was also placed into the tank to attempt to remove some of the heavier particles present. Air flow was set at 11321/min (40 SCFM) and the foam was initially removed every 4 minutes. The test was stopped when the drain time dropped to about 2.75 seconds, approximately 12 hours and 30 minutes from start of test. 3.3 Environmental Tests Before and after water samples from the AFFF QPL tests and the storage tank were tested for COD, BOD5, TPH, BTEX, pH and MBAS. Additionally, standard samples of AFFF solution were also tested for MBAS to determine if the MBAS test was suitable for the AFFF-type surfactants. All of these tests were run in accordance with EPA approved methods as follows: TEST BODs COD MBAS BTEX VPH TPH pH EPA METHOD 405.1 ppm 410.4 ppm 425.1 ppm 8020 ppb 8015-M ppb 418.1 ppb N/A 5 US00006697 4.0 RESULTS AND DISCUSSION 4.1 AFFF Surfactant Reduction The concentration of the AFFF surfactants was calculated from the drain time measurements using the drain time versus concentration plots previously developed and provided in Figures 1 and 2 [3]. The drain time at the start of the MILSPEC TEST sample was 10.93 seconds representing a concentration of approximately 1350 ppm. The drain time at the end of the test was 0.83 seconds representing a concentration of approximately 240 ppm. The initial drain time of the WASTEWATER sample was 17.13 seconds or about 1800 ppm. After running through the separator the drain time was reduced to 2.77 seconds corresponding to about 500 ppm of AFFF surfactants. These tests confirmed that the separator adequately reduces the AFFF surfactant concentration with both of these types of firefighting wastes. 4.2 Environmental Tests The results of the environmental tests and the separator tests are provided in Table 1. The same headings for MILSPEC TEST and WASTEWATER are used. Samples captured for environmental testing just prior to running the AFFF Separator are labeled BEFORE. Samples taken after AFFF separation are labeled AFTER. The values given as `less than' using the "<" symbol are at or below the detection limits for that analysis, as provided in the Report of Analysis from Gascoyne Laboratories, Inc., Appendix A. An analysis of the BEFORE and AFTER samples from the MILSPEC TEST and the WASTEWATER indicate that all measured quantities are decreasing. The effluent from the AFFF separator contains considerably less AFFF surfactants and is less polluting as measured by the environmental tests. The reductions can be significant. This is particularly true for the more volatile species measured in the BTEX and VPH tests versus the heavier organics measured in the TPH test. This result is expected with the aeration technique used in the AFFF Separator. The MILSPEC TEST BEFORE sample was extremely high in VPH and BTEX, and had the highest COD of the group. There is good rationale for the observed high value of the COD test from the results of BTEX and VPH. However, this same reasoning does not hold true for the concentration of BTEX and VPH versus the BODs results. The BODs was not very high which was unexpected based on the composition of the wastewater. Further analysis revealed that the BODj test that is prescribed by the wastewater treatment plants and recommended for this study is not suitable for this type of wastewater . The BOD20test is apparently needed to provide enough time for the particular organics present to react with the bacteria. All future testing should require the 20 day BOD test instead of the 5 day test to more adequately characterize these wastes. 6 US00006698 US00006699 Fig. I - Average Drain Time vs. Concentration for AM* F (6%) Solutions US00006700 Fig. 2 - Average Drain Time vs. Concentration for AFFI (6%) Solutions It is typical when making comparisons between the environmental tests that it is difficult to assign particular concentrations to particular results between different wastes. To overcome this problem the BEFORE and AFTER data is compared by percent reduction. The percent reduction is defined as: (initial concentration - final concentration) / initial concentration The results in Table 1 that are below the detection limits are assigned the value of the detection limit. This assumption provides the maximum percent reduction that is possible. The results that are given as None Detected (ND) are given a value of 0 also reporting the maximum percent reduction possible. Table 2 lists the results of this analysis for the AFFF surfactant and the environmental tests. Table 1 - Results of Environmental Tests TEST MILSPEC TEST MILSPEC TEST WASTEWATER WASTEWATER BEFORE AFTER BEFORE AFTER DRAIN TIME in PPM 1350 240 1800 500 BIOCHEMICAL OXYGEN DEMAND in mg/l (PPM) <1000 220 1,100 870 CHEMICAL OXYGEN DEMAND in mg/l (PPM) 13000 2400 4,700 3,100 METHYLENE BLUE ACTIVE SUBSTANCES in mg/l (PPM) 13 3.7 98 29 TOTAL PETROLEUM HYDROCARBON in mg/l (PPM) Not Taken Not Taken 140 94 VOLATILE PETROLEUM HYDROCARBONS in ua/l (PPB) 2,000,000 100,000 300,000 65,000 BTEX BENZENE in gg/l (PPB) TOLUENE in ua/l (PPB) ETHYLBENZENE in ua/l (PPB) XYLENES in ug/l (PPB) 20,000 32,000 3200 17,000 200 <100 ND ND 700 2000 500 2400 200 ND ND <300 ________________________ 8.1 8.5 5.6 5.6 9 US00006701 The MILSPEC TEST samples contained volatile organic compounds that are effectively removed by the aeration process in the separator. The BTEX and VPH are reduced by over 95%. The MBAS, BOD5and COD are reduced by 78 - 82%, providing excellent agreement. This would seem to imply that the COD and BOD5tests are adequately taking into account the AFFF surfactants. The results of the WASTEWATER samples are not as straight forward. While the percent reduction of the more volatile organics as evidenced by the BTEX and VPH results is still quite large, they do not correlate well with the change in COD. There may be several reasons for this. The starting concentration for VPH and BTEX are considerably lower for the WASTEWATER samples than for the MILSPEC TEST samples. As such they do not contribute as much to the COD results. The concentrations for BTEX and VPH for both AFTER samples are in the same concentration range. Using the values for VPH from Table 1 for AFTER samples of MILSPEC TEST and WASTEWATER, the results are 300,000 ppb and 65,000 ppb respectively. There may be a lower limit to the reduction of VPH using the AFFF separator so that the percent reduction analysis is misleading. Lastly, the presence of heavy hydrocarbons that are not as effectively removed by the aeration process may be more responsible for the COD than the volatile hydrocarbons for the WASTEWATER samples. The percent reductions between the TPH, COD and BODs are in better agreement than any other tests of the WASTEWATER samples. This would seem to imply that the AFFF surfactants are not affecting the changes in the BOD5or COD very much, if at all. This discrepancy between the MILSPEC and WASTEWATER samples is not explainable at the current time with the limited test data available. Table 2 - Percent Reductions between BEFORE and AFTER Samples TEST DRAIN TIME BOD, COD MBAS TPH VPH BTEX BENZENE TOLUENE ETHYLBENZENE XYLENES MILSPEC TEST WASTEWATER % REDUCTIONS % REDUCTIONS 82% 72% 78% 21% 82% 34% 72% 70% NA 33% 95% 78% 99% 100% 100% 100% 71% 100% 100% 88% 10 US00006702 4.3 MBAS and Drain Time Correlation To determine if the MBAS test could be correlated to the drain time results, four standard samples of Angus 3% MILSPEC AFFF were prepared: 1000 ppm, 500 ppm, 100 ppm, and 10 ppm. These samples were prepared using the same concentration assumptions used in the previous work [3]. The drain time for the standards were measured and the concentrations determined using the drain time versus concentration plots provided in Figures 1 and 2. The results are provided in Table 3. The drain time concentration values for the two samples below drain time detection limits are estimated using the average values from the drain time data and are shown in italics. Table 3 - Drain Time and Concentration of AFFF Standard Solutions CONCENTRATION DRAIN TIME CONCENTRATION BY DILUTION, PPM SECONDS BY DRAIN TIME, PPM 10 ND 7 100 ND 68 500 2.29 360 1000 4.34 670 The concentrations based on drain time are approximately 30% lower than predicted from dilution. This is not unexpected. Firstly, there were considerable assumptions made in the previous work in determining the concentration of the AFFF surfactants. Secondly, the AFFF used for this study is different than the one used for the previous study, Angus 3% MILSPEC AFFF versus 3M 6% MILSPEC AFFF (FC-206 CF), respectively. It is reasonable to expect that there are different concentrations of surfactants between the two proprietary formulations. These four standard solutions and a control blank with the same water used to dilute the standards were sent for MBAS analysis. The results are provided in Table 4 with the results for the MILSPEC and WASTEWATER samples. Table 4 - Drain Time Concentration versus MB AS Results CONCENTRATION MBAS SAMPLE BY DRAIN TIME, PPM PPM S-2 (CONTROL BLANK) 00 S-1 7 0.05 S-4 70 0.44 S-5 360 4.4 S-3 670 7.4 MILSPEC BEFORE MILSPEC AFTER 1350 13 240 3.7 WASTEWATER BEFORE WASTEWATER AFTER 11 1800 98 500 29 US00006703 The intent was to determine if the MBAS results could be used to determine the concentration of AFFF surfactants. A Correlation Factor was developed by dividing the drain time concentration by MBAS. The results are provided in Table 5. The results for the standards and the MILSPEC TEST samples all appear to be in the same range. However, the WASTEWATER results are an order of magnitude higher for similar drain time concentrations. Possible explanations for this discrepancy are provided later in the report. The average Correlation Factor of 106 for the four standards and the MILSPEC tests is used to calculate concentrations based on the MBAS. The results are also provided in Table 5 with the percent difference between the two concentrations. Table 5 - Drain Time-based Concentration versus MBAS-based Concentration in ppm SAMPLE S-2 S-1 S-4 S-5 S-3 DRAIN TIME CONCENTRATION 0 7 70 360 670 MBAS CORRELATION MBAS FACTOR CONCENTRATION DIFFERENCE 0 NA 0 NA 0.05 139 5 23% 0.44 158 47 33% 4.4 82 468 -30% 7.4 91 787 -17% MILSPEC BEFORE MILSPEC AFTER 1350 240 13 3.7 104 65 1382 393 -2% -64% WASTEWATER BEFORE WASTEWATER AFTER 1800 500 98 29 18 10421 -479% 17 3084 -517% The results for the standard samples are the best with absolute value percent differences ranging 17 to 33 % but the values for the others are not as good (i.e., 2 - 64% for MILSPEC TEST samples and 479 to 517% for WASTEWATER samples) and would not provide an adequate estimation of the AFFF surfactants. There are several possibilities why this may be occurring. The MBAS test that is specified by the wastewater treatment plants is for anionic surfactants only. However, AFFF is a complex mixture of surfactants that may include anionic, non-ionic and cationic surfactants, and therefore only an unknown portion of the surfactants may be accounted for in this test. Secondly, the test was developed for typical surfactants used as detergents and is reported as LAS [5], In calculating the results in a certain molecular weight is assumed that is almost certainly different from the molecular weight(s) of the AFFF surfactants. The results, therefore, would not be linear. Lastly, there may be chlorides in the WASTEWATER samples that are interfering with the results [5], Chlorides may be present in the wastewater because the QPL test 12 US00006704 requires testing AFFF formulations with simulated salt water. The MBAS test alone does not appear to be adequate to determine the concentration of AFFF surfactants. There is another environmental test that may be used to measure non-ionic surfactants, Cobalt Thiocyanate Active Substances (CTAS). It is recommended that future work include both the MBAS and CTAS tests to determine if the combined results correlate to the drain time concentrations. There does not appear to be an EPA test method for cationic surfactants. The rationale is that the cationic surfactants represent only a small fraction of the total quantity of surfactant manufactured in the U.S. Unfortunately, the percent of cationic surfactants within AFFF formulations may be considerably higher than the U.S. average. 4.4 Summary The AFFF separator is reducing the AFFF surfactants for these typical firefighting waste waters as well as it performed with `pure' AFFF- water solutions. The presence of contaminants that would typically be found in firefighting wastes, such as petroleum hydrocarbons and aromatic compounds, do not appear to adversely affect the mechanism or the efficiency of the process. In addition, the separator is reducing the other pollutants in the waste as measured by BODj, COD, VPH, BTEX and TPH. The concomitant reduction can be significant, e.g., 95 to 100%, particularly for the more volatile species. The overall results are extremely encouraging and continued development of the AFFF separator is recommended, as discussed below. 5.0 CONCLUSION 1. The AFFF separator is able to reduce the AFFF surfactant concentrations of the firefighting wastewaters tested. Typical contaminants such as petroleum fuels and volatile aromatic compounds do not have an adverse effect on the final surfactant reduction process or final concentration. 2. The AFFF separator is also reducing the volatile petroleum hydrocarbons and aromatic compounds through the aeration process. The results from all of the environmental tests indicate that the effluent from the AFFF separator is less polluting than the original wastewater as based on COD and BOD5. 3. The BODj test is not adequate to characterize the typical firefighting wastewaters tested. A longer residence time is apparently needed for the bacteria to consume the organics. It is recommended that the BOD20test be specified for all future testing. 4. The tests did not lend any insight into whether or not the AFFF surfactants are breaking down in the BOD or COD tests. The limited data does not provide any insight to this question. 13 US00006705 5. The MBAS test alone does not adequately correlate to the AFFF concentrations as measured by drain time. The environmental test for CTAS should also be included in any further testing. 6. It is not possible to determine whether these wastewaters would be acceptable to the wastewater treatment plants at CBD or Hampton Roads as direct influent. The degree of dilution with other influent wastewaters will impact this decision. However, the separator is improving the wastewater and should assist in making these effluents acceptable. 7. The results are extremely encouraging and continued development of the separator suitable for field testing is recommended. 6.0 REFERENCES 1. Military Specification, "Fire Extinguishing Agent, Aqueous Film-forming Foam (AFFF) Liquid Concentrate, for Fresh and Seawater," MIL-F-24385F, 7 January 1992. 2. Darwin, R. L., Ottman, R.E., Norman, E.C., Gott, J.E, and Hanauska, C.P., "Foam and the Environment: A Delicate Balance," NFPA Fire Journal, Vol. 89 No. 3, May/June 1995, pp. 67-73. 3. Beitel, J. J., Bums, R.E., Ouellette, R, and Szepesi, D., "Tests for Mechanical Separation of AFFF in Firefighting Waste Water," draft, 15 December 1995. 4. Hampton Roads Sanitation District, "Industrial Wastewater Discharge Regulations,", November 1, 1990. 5. Kopp, J.F. and McKee, G.D., "Methods for Chemical Analysis of Water and Wastes," United States Environmental Protection Agency, March, 1983. 6. Gascoyne Laboratories, Inc., "Client Reference Guide,", January 1, 1995. 14 US00006706 7. Department of the Navy, "Qualified Products List of Products Qualified under Military Specification MIL-F-24385 Fire Extinguishing Agent, Aqueous Film Forming Foam (AFFF) Liquid Concentrate, for Fresh and Sea Water," Naval Sea Systems Command QPL-24385-25, Washington, DC, 21 May 1992. J Ffw . WILLIAMS, Director Navy Technology Center for Safety and Survivability Code 6180 Robert E. BURNS, President Hughes Associates, Inc. Baltimore MD D. P. VERDONIK Hughes Associates, Inc. Baltimore MD ^d . ' L c . Ralph J. OUELLETTE Hughes Asspcoates. Inc. Baltimore MD 15 US00006707 Oasmmtt' V-fTt V Report No. 96-03-124 ILabnrirics., 3 tir. Baltimore, MD21224-6697 .-\ i1! L -bibi Report Date: M a r c h 20, -'3 633--Scc 3YNCO- GAS-C; -AX NC - ' 0 533-5-U j 1996 Report To: Hughes Associ a t e s Page: l of 15 Sample I.D. S u b m i t t e d Water: CBD/K-09, W W I , d a t e d 0 3 / 06/96 (0815) Benzene Toluene Ethylbenzene Total Xylenes Volatile Petroleum Hydrocarbons (reported as gasoline, C4 to C12) Results 700 2,000 500 2,400 300,000 Detection Limits 100 100 100 300 10,000 Sur r o g a t e R e c o v e r y (%) Trifluorotoluene 99 Dilution Factor: 100 Notes (1) R e s u l t s e x p r e s s e d as ug/ 1 ( p p b ) . (2) A n a l y s i s p e r f o r m e d a c c o r d i n g to m e t h o d E P A 8 0 2 0 / 8 0 1 5 -M. (3) A nalyst(s): CPB; Date Test C ompleted: 03/12/96. Laboratory Director APPENDIX A US00006708 rfr 11'|'\ ' I ~J >v U w scew E n m i $ r Report N o . Report To : Sample I .D semini' ILaiinrninrii's, 3nr. 96-03-124 Baltimore, MD21224-6697 :rOr- i AL ^ Report Date: M a r c h 20, -10: n33-?30C SCOI GAS-CC'- \ -AX `jO JIOI ^33-5"2, 1996 Hughes Associates Page : of 15 Submitted Water: CBD/K-09, WWII, dated 03/06/96 (0830) Benzene Toluene Ethylbenzene Total Xylenes Volatile Petroleum Hydrocarbons (reported as gasoline, C4 to C12) Results 200 ND ND <300 65,000 Detection Limits 100 100 100 300 10,000 S u r r o g a t e R e c o v e r y (%) Trifluorotoluene 117 Dilution Factor: 100 Notes (1) Resu l t s e x p r e s s e d as ug/ 1 (ppb). (2) A n a l y s i s p e r f o r m e d a c c o r d i n g to m e t h o d E P A 8020/8015-M. (3) A n a l y s t ( s ): CPB; Dat e Test Completed: 03/12/96. Laboratory Director A-2 US00006709 ( a s rn m u ' iL a b u r a h ir iu s , lih ic 1<,O'.r7ii#w1*; A j* uca O'-orO'1 Report No. 96-03-124 Report To: Hughes Associates Sample I .D. S u b m i t t e d Water: -- i .N L7 ?!S J.101 5 3 2 -'BOO 8001GAS-CGVN FAX NO. .4101 633-5443 Report Date: M a r c h 20, 1996 Page : of 15 Benzene Toluene Ethylbenzene Total Xylenes Volatile Petroleum Hydrocarbons (reported as gasoline, C4 to C12) Results Detection Limits 20,000 1,000 32,000 1,000 3,200 1,000 17,000 3,000 2,000,000 100,000 Sur r o g a t e R e c o v e r y (%) Tri fluorot oluene 98 Dilution Factor: 1000 Notes (1 ) Results expressed as ug/1 (ppb). (2 ) Analysis performed according to method EPA 8020/8015-M. (3) Analyst(s): CPB; D a t e T e s t Completed: 03/12/96. A-3 William L. Lock Laboratory Director US00006710 f e c t s m m u ' i L a i i o r a i t f n e s . iln c . GfiSC'zlF ' im } Report N o . 96-03-124 Baltimore. MD21224-6697 qnr. O P T P F A M T I O / 3 1 S Report Date : M arch 20, 4101633-1800 ,3001GAS-COYN FAX NO 4101633-5443 1996 Report To: H u g h e s A s s o c i a t e s Page : 4 Of 15 Sample I .D. S u b m i t t e d Water: CBD/K-09, M S I I , d a t e d 03/06/96 (0850) Benzene Toluene Ethylbenzene Total Xylenes Volatile Petroleum Hydrocarbons (reported as gasoline, C4 to C 1 2 ) Results 200 <100 ND ND 100,000 Detection Limits 100 100 100 300 10,000 Surrogate R e c o v e r y (%) Trifluorotoluene 95 Dilution Factor: 100 Notes {1} R e s u l t s e x p r e s s e d as ug/1 ( p p b ) . (2) A n a l y s i s p e r f o r m e d a c c o r d i n g to m e t h o d E P A 8020/8015-M, (3) A n a l y s t ( s ) : C P B ; Date T e s t Completed: 03/12/96. William L. Lock Laboratory Director A-4 US00006711  CMr*^. OlasrntJiti' Xabnrainrtt's, 3lnc- Report N o , 96-03-124 Baltimore. MD 21224-6697 C?llLI--^ It"i ^ Oi i1 ! :"'l-1 A N A L Y SIS J-1I 6 3 3 -'SCO 3001 GAS-COYN PAX NO -1101 633-5A-13 R e p o r t Date: M a r c h 20, 1996 Report To : Hughes Associates Page: 5 of 15 Sa m p l e I.D. S u b m i t t e d Water: CBD/K-09, W W I , d a t e d 0 3 / 0 6 / 9 6 (0815) Test Detection Results Limits Method Biochemical Oxygen Demand Chemical Oxygen Demand D e t e r g e n t s (MBAS) pH 1,100 4,700 98 5.6 300 1,000 4 NA EPA 405.1 EPA 410.4 EPA 425.1 EPA 150.1 Date Test Analyst Completed RAH PBK PBK GB 03/12/96 03/13/96 03/07/96 03/06/96 Notes (1) Results expressed as mg/1 (ppm). A-5 W i l l i a m L. Loc k Laboratory Director US00006712 ascamti' Caljorahirit's, -31m:. Report N o . 96-03-124 Baltimore, MD21224-6697 EPORT OF AMALO OO, 633-1300 300: 3 A 3 - GOVN r AX NO ): 633- 54-13 Report Date: M a r c h 20, 1996 Report To : Hughes Associates Page: 6 of 15 Sample I.D. S u b m i t t e d Water: CBD/K-09, W W I , d a t e d 0 3 / 0 6 / 9 6 (0815) Total Pet. Hydrocarbons Test Detection. Results Limits Method 140 1 EPA 418.1 Date Test Analyst Completed PRM 03/15/96 Notes (1) Results expressed as mg/1 (ppm). William L. Cock Laboratory Director A-6 US00006713 O ic ts r U i' I L u t b o r a h ir it 's , 3 n c . (tfs c & rtn \ JBS - Report N o . Report T o : Sample I .D. 96-03-124 Baltimore. MD21224-6697 : 1 L^. ' F F 7 O F M A L V 3 1 3 Report Date : M a r c h 20, J10i 633"SCC 3001 GA S-CCV ' =AX MO J10: 532-443 1996 Hughes Associates Page : 7 of 15 Submitted Water: CBD/K-09, WWII, dated 03/06/96 {0830} Test Detection Results Limits Method Biochemical Oxygen Demand Chemical Oxygen Demand Detergents (MBAS) pH 870 3,100 29 5.6 300 1,000 2 NA EPA 405.1 EPA 410.4 EPA 425.1 EPA 150.1 Date Test Analyst Completed RAH PBK PBK GB 03/12/96 03/13/96 03/07/96 03/06/96 Notes (1) Results expressed as mg/1 (ppm). William L. Lock Laboratory Director A -7 US00006714 a s c a m it' iL it iin r u h in ^ s , 3 ln c . 96-03-124 Baltimore. MD21224-5697 ir ORT OF TMFLORIS Report Date: M a r c h 20, 410; 623-1800 300I GAS-COYN FAX NO 410;633-5443 1996 Report To : Hughes Associates Page: 8 of 15 Sample I.D. S u b m i t t e d Water: CBD/K-09, WWII, d a t e d 03/06/96 (0830) Total Pet. Hydrocarbons Test Detection Results Limits Method 94 1 E P A 418.1 Date Test Analyst Completed PRM 03/15/96 Notes R e s u l t s e x p r e s s e d as m g / 1 (ppm) William^L . Lock Laboratory Director A-8 US00006715 fe a s c u tn u ' 96-03-124 I L a iio r h id r ib s ^ 7 3- nc Baltimore. MD21224-6697 EPOP^ OF AMAL'/SI 3 -101 6 3 3 - ' aco 3Q0I GAS-COYN CAX NO YiOl 633-5-A3 R e p o r t Date: M a r c h 20, 1996 Report To : Hughes Associates Page: 9 of 15 Sample I .D . S u b m i t t e d Water: CBD/K-09, MSI, d a t e d 0 3 / 06/96 (0840) Test Detection Results Limits Method Biochemical Oxygen Demand Chemical Oxygen Demand D e t e r g e n t s (MBAS) PH ND 13,000 13 8.1 1,000 1,000 1 NA EPA EPA EPA EPA 405.1 410.4 425.1 150.1 Date Test Analyst Completed RAH PBK PBK GB 03/12/96 03/13/96 03/07/96 03/06/96 Notes (1) Results expressed as mg/1 (ppm). A-9 Laboratory Director US00006716 Oiascumu' X a b o ra iiirits, 3 tur. *1 'V I s/i, v4O, -S / j Report No. 96-03-124 Baltimore, MD21224-6697 -t F OFi i F aN AL'v'SS 4 ` C T33 -1800 800 G3-CCYN - I X NO. ~i0i 333-5443 Report Date: M a r c h 20, 1996 Report To: Hughes Associates Page : 10 of 15 S a m p l e I .D. S u b m i t t e d Water: CBD/K-09, MSII, d a t e d 0 3 / 0 6 / 9 6 (0850} Test Detection Results Limits Method Biochemical Oxygen Demand Chemical Oxygen Demand D e t e r g e n t s (MBAS) PH 220 2,400 3.7 8.5 50 500 0.5 NA EPA 405.1 EPA 410.4 EPA 425.1 EPA 150.1 Date Test Analyst Completed RAH PBK PBK GB 03/12/96 03/13/96 03/07/96 03/06/96 Notes (1} Results e x p r e s s e d as m g / 1 ( p p m ) . ^ 5# Willianv^L. Lock Laboratory Director A-10 US00006717 J!Oi 633-1800 8001 G A 3-C 0 Y N FAX NO 4101 633-5443 Report To : Hughes Associates Page: 11 of 15 Sample I .D . S u b m i t t e d Water: CBD/K-09, S2, d a t e d 03/06/96 (0900) Detergents (MBAS) Test Detection Results Limits Method ND 0.02 EPA 425.1 Date Test Analyst Completed PBK 03/07/96 Notes (1 ) R e s u l t s exp r e s s e d as m g / 1 (ppm) . Willi^raKL. Lock Laboratory Director A - 11 US00006718 (Sasmmtt' ILaborafant's. ^7 Baltimore, MD21224-6697 ' \ L , PORT OF AMAL''.'315 ldi 633-SGC 3001 GAS-COVN Report No. 96-03-124 -AX MO A101 633-5443 Re p o r t Date: M a r c h 20, 1996 Report To: Hughes Associates Page: 12 of 15 Sample I.D. S u b m i t t e d Water: CBD/K-09, SI, d a t e d 03/06/96 (0900) D e tergents (MBAS) Test Detection Results Limits Method 0.05 0.02 EPA 425.1 Date Test Analyst Completed PBK 03/07/96 Notes (1) Results expressed as mg/1 (ppm). William L. Lock Laboratory Director A - 12 US00006719 (>ctscotitu.' jJLaioratnres, Unz. f- < / Y y ' ' i i:iji Xt /{flsrcTff .v n -cs / j Report No. 96-03-124 Baltimore, MD21224-6697 FEPORY Of AMALY3S Report D a t e : M a r c h 20, 4i0i633-moo 300)GAS-COYN FAX NO .4101633-5443 1996 R e p o r t To: H u g h e s A s s o c i a t e s P a g e : 13 of 15 Sample I .D. S u b m i t t e d Water: CBD/K-09, S3, d a t e d 0 3 / 0 6 / 9 6 (0900 ) D e t e r g e n t s (MBAS) Test Detection Results Limits Method 7.4 0.5 EPA 425.1 Date Test Analyst Completed PBK 03/07/96 Notes (1) Results expressed as mg/1 (ppm). Atfilliam LA Lock Laboratory Director A-13 US00006720 ascatrm; ^Caiioraiurms, -dim:. 96-03-124 Baltimore. MD 21224-6697 FEPOFT OF ANALYSIS Report Date: M a r c h 20, 410; 33-1300 3001GAS-COYN FAX MO 4101633-5443 1996 Report To : Hughes Associates Page: 14 of 15 S a m p l e I.D. S u b m i t t e d Water: CBD/K-09, S 4 , d a t e d 0 3 / 0 6 / 9 6 (0900) D e t e r g e n t s (MBAS) Test Detection Results Limits Method 0.44 0.04 EPA 425.1 Date Test Analyst Completed PBK 03/07/96 Notes (1) Results e x p r e s s e d as m g / 1 ( ppm). A-14 lock Laboratory Director US00006721 asnunte ILaboraiurtt's, 3ttc. 96-03-124 Baltimore. MD 21224-6697 REPORT OF AM AL VS] Report Date: M a r c h 20, 4101 633-1 300 3001 GAS-CCVN FAX NO ;410l633-5443 1996 Report To : Hughes Associates Page: 15 of 15 Sample I.D. S u b m i t t e d Water: CBD/K-09, S5, dated 03/06/96 (0900) Detergents (MBAS) Test Detection Results Limits Method 4.4 0.2 EPA 425.1 Date Test Analyst Completed PBK 03/07/96 Notes (1) Results expressed as mg/1 (ppm). A -15 william L. Lock Laboratory Director US00006722 DEPARTMENT OF THE NAVY NAVAL RESEARCH LABORATORY 5 5 OVERLOOK AVE SW WASHINGTON DC 20375-5320 nert_y b c f e h t o 3905 Ser 6180/0603 Bfl C: 936 From: Commanding Officer, Naval Research Laboratory To: Commander, Naval Facilities Engineering Service Center (Code ESC 421 R. Lee), 560 Center Drive, Port Hueneme CA 93043 Subj: SEPARATION YIELDS FOR MECHANICAL SEPARATION OF AFFF IN FIREFIGHTING WASTEWATER Enel: (1) Two copies o f subject report. 1. Enclosure (1) is forwarded for your information. 2. This report provides estimates o f AFFF wastewater throughput for various sizes o f separators and concentrations o f AFFF. These data can be used to assess the feasibility o f a portable, trailer-mounted separator. The estimates would have to be verified experimentally to determine if scale-up assumptions (i.e., surface area, depth, and air flow rates) are appropriate. 3. The NRL point o f contact is Dr. Frederick W. fwilliams@itd.nrl.navy, mil. Copy to: COMNAVSEASYSCOM (Code 03G Darwin) NFEC (Gott) LANDIS/NAVFAC (Code 18111 Clark) US00006723 6180/0603A. 1:FWW 3 October 1996 Subj: SEPARATION YIELDS FOR MECHANICAL SEPARATION OF AFFF IN FIREFIGHTING WASTEWATER Ref: (a) (b) Leonard, J. T., Burns, R.E., Ouellette, R.J., Verdonik, D.P. and Williams, F.W., "Environmental and Efficacy Tests for AFFF Separator Using Actual Firefighting Wastewaters," NRL Ltr Rpt 6180/0572, 27 September 96 Leonard, J .T ., Beitei, J.J., Bums, R.E. Ouellette, R.J. and Williams, F.W., "Separation o f AFFF in Firefighting Wastewater", in preparation 1. Background - Previous work has demonstrated the efficacy o f mechanical separation o f AFFF in firefighting wastewater (references (a) and (b)). While the majority o f this work was with laboratory-scale apparatus, several tests were conducted on larger apparatus. This apparatus was 0.9 m x 2.4 m x 0,9 m high ( 3 f t x 8 f t x 3 f t high). Based on air flow rates and data from three tests, a basic processing rate chart was developed (Fig. 1). The chart shows that the processing rate is dependant on the starting concentration o f AFFF in the water. As shown, the processing rate (L/hour (gal/hour)) decreases with increasing AFFF concentrations. 2. Processing Analysis - Additional analyses were requested to provide information relating to the estimated time required to process AFFF in wastewater. This "first-cut" throughput analysis would be used to make an interim assessment of the feasibility o f a trailer-mounted separator unit. This analysis is based on two assumptions: It is assumed that an end point as measured by drainage time is appropriate. This end point is an 8-second drainage time which corresponds with 1000 ppm o f AFFF left in solution. p -p p It is assumed that the processing rate as determined in the large experimental apparatus will directly scale-up with respect to square footage o f the tank and the solution depth in the tank. Using these assumptions and the process rate chart shown in Fig. 1, the processing time for varying amounts o f wastewater can be determined. As bounding conditions, it was assumed that a 0.3 percent and a 2.2 percent concentration o f 3 percent AFFF in solution existed. The 0.3 percent concentration o f 3 percent AFFF has a process rate o f 170 L/hour (45 gal/hour) while the Enel (1) to NRL Ltr 3905 Ser 6180/0603 US00006724 Process rate (Iph) Concentration of 3% AFFF (%) Fig. 1 - Process rate of AFFF wastewater in large experimental apparatus US00006725 2.2 percent concentration o f 3 percent AFFF in solution has a process rate o f 35 L/hour (9.3 gal/hour). The large test apparatus is capable o f processing a 946 L (250 gal) batch load at a time (the tank is filled to half capacity, with the top half used to collect the foam). If this tank is used to process 3785 L (1000 gal) o f wastewater, the process time can be estimated: 0.3 percent concentration, apparatus holds 946 L/charge (250 gal/charge), a single charge o f 946 L (250 gal) requires 5.5 hours to process (Fig. 1, 170 L/hr (45 gal/hr) process rate), and 3785 L (1000 gal) requires four charges, and therefore, the total process time is 22 hours. If the 2.2 percent concentration is used, the total process time (four charges and 35 L/hour (9.3 gal/hour)) is -108 hours. These times do not include time for drainage and refilling for each charge. As shown, the processing time is dependant on the size o f the processing tank (number o f charges) and the gallons o f solution. For example, if four tanks were available (each 946 L (250 gal)), then the processing times would be as follows: 0.3 percent concentration would require -5.5 hours, and 2.2 percent concentration would require -2 7 hours. If it is assumed that the processing rate would directly scale-up with a large tank (in place o f four tanks each), then the processing rate can be expressed as a function o f the surface area o f the separator. Fig. 2 shows this relationship. The effect o f various sizes o f processing tanks is shown in Fig. 3. In this Figure, three different sizes o f tanks were analyzed. It is assumed that the depth o f solution is constant (46 cm (18 in.)). The data represent the possible amount o f AFFF that can be processed in a 24-hour period. This assumes no downtime for recharges. Fig. 3 shows that if the tank is larger (greater footprint), then the processing time is reduced for the same quantity o f wastewater. Alternately, greater amounts o f wastewater can be treated in the same amount o f time. If an eight hour "shift" is assumed, the throughput times in Fig. 3 would be reduced by two-thirds. 4. If it is assumed that increasing the depth o f the tank does not affect the processing rate, then further economies could potentially be attained. This is, however, unclear based on limited test data available. 3 Process rate (Iph / m2) Concentration of 3% AFFF (%) Fig. 2 - Process rate of AFFF wastewater as a function of surface area US00006727 8000 7000 6000 5000 4000 3000 2000 1000 0 Fig. 3 - Estimated throughput of AFFF wastewater for various size separators 5. Estimated quantities and composition o f wastewater from training facilities can be compared to the throughput estimates in Fig. 3. The separators assumed in Fig. 3 could potentially be trailer-mounted. Total weight would have to be factored into the ultimate design. 6. Future W ork - As discussed in the earlier work, scale-up o f the process must be performed to validate the processing rate data. Scale-up should include optimization o f air flow rates, larger size tanks, and increased depths o f solution. Since this is a batch process, a more efficient technique may be worth considering, i.e., a continuous feedstock process. For limited quantities o f AFFF the batch processes seems reasonable but for large quantities o f wastewater in the 10,000's o f gallons the process would be labor intensive and time consuming. ^FR E D ER IC K W. WILLIAMS Director, Navy Technology Center for Safety and Survivability Code 6180 /E S S E J. BEITEL Sensior Scientist Hughes Associates, Inc. Baltimore MD 6 US00006729 DOT/FAA/CT-94/04 FAA Technical Center Atlantic City International Airport, N.J. 08405 Analysis of Test Criteria for Specifying Foam Firefighting Agents for Aircraft Rescue and Firefighting 6 t This document is available to the public through t ie Nafiooal Technical information Service, Springfield, Virginia 22161. O U.S. Department of Transportation Federal Aviation Administration US00006730 NOTICE This d ocum ent is dissem inated under the sponsorship of the U .S . Departm ent of Transportation in the interest of information exchange. The United States Governm ent assumes no liability for the contents or use thereof. The United States Governm ent does not endorse products or m anufacturers. Trade or m anufacturer's nam es ap p ear herein solely because they are considered essential to the object of this report. US00006731 1 Report NO- 2. Government Accession No. DOT/FAA/CT-94-04 4 Title and SuOtitie ANALYSIS OF TEST CRITERIA FOR SPECIFYING FOAM FIREFIGHTING AGENTS FOR AIRCRAFT RESCUE AND FIREFIGHTING 7 Authors} Joseph L. Scheffey* Joseph A. Wright Technical Report Documentation Page 3. Reapient s Catalog No. 5. Report Date August 1994 6. Perform ing Organization Code 8. Performing Organization Report Mo. 9. Performing Organization Name and Address `Hughes Associates, Inc. 6770 Oak Hall Lane, Suite 125 Columbia, MD 21045 12. Sponsoring Agency Name and Address U.S. Department of Transportation Federal Aviation Administration Technical Center Atlantic City International Airport, NJ 15 Supplementary Notes 08405 FAA Project Manager: Joseph A. Wright, ACD-240 10. Worts Unit No. (TRAIS) 11. Contract or Grant No. 13. Type of Report and PeikKJ Ccvered Final 14. Sponsoring Agency Code ACD-240 16. Abstract Foam agent quantities and application rates for FAA certified airports are based on large-scale fire test data of Aqueous Film-Forming Foam (AFFF) and protein-based foams. The philosophy is to control aircraft fuel fires in sixty seconds. Foam agents which are used for aviation applications should demonstrate this level of performance, including a safety factor which assures adequate performance under less than optimum conditions. A review of standard test methods and performance criteria indicates a wide range of requirements. The U.S. Military Specification (MIL SPEC) for AFFF, on which the original agent criteria was developed, is the most stringent in terms of extinguishment application density. However, no direct correlation has been demonstrated between many of the required physical/chemical properties tests and fire extinguishment/burnback performance. It was demonstrated, using comparative data from numerous small- and large-scale fire tests, that the small-scale MIL SPEC fire tests correlate with large-scale test results. MIL SPEC agents, which provide a safety factor over minimum FAA requirements, also are formulated to have proportioning, storage, stability, and shelf-life attributes appropriate for crash rescue firefighting applications. Adoption of the MIL SPEC for AFFF agents is recommended. Future work related to foam testing should focus on the use of first principles to establish fundamental foam extinguishment mechanisms. 17 K e yw o rd s 18. Distribution Statement Foam, foam testing, AFFF, Military Specification, Aircraft crash rescue firefighting, Hydrocarbon fuels, spreading co-efficient, Protein foam, surface tension, Expansion, drainage, foam standards This document is available to the public through the National Technical Information Service, Springfield, Virginia 22161 19 Security Classrf. For official use only. 20. Security Classit. Unclassified 21. No. of Pages 93 22. P n Form DOT F1700.7 (s-72) Reproduction ot completed page authorized US00006732 PREFACE The intent of this work, performed by Hughes Associates, Inc., was to review available test data and regulations and standards related to foam agent performance. Based on this review, recommendations are made for appropriate specifications for the Federal Aviation Administration (FAA) to adopt so that adequate performance is achieved when certified airports procure firefighting foam. The evaluation relied strictly on existing test data; no testing was performed specifically for this evaluation. The data include previously unpublished data of tests performed by George Geyer of the FAA, which was presented at the International Conference on Aviation Fire Protection, Interlaken, Switzerland, in September 1987. The contributions of Mr. Geyer, which also include much of the earlier, baseline data, are recognized. 111 US00006733 TABLE OF CONTENTS EXECUTIVE SUMMARY BACKGROUND OBJECTIVE APPROACH HISTORICAL BASIS FOR FOAM REQUIREMENTS The Survivable Post-crash Aircraft Accident Critical Application Rates Summary and Key Factors Description of Agents STANDARDS AND REGULATIONS National Standards and Test Methods International Standards Performance Fire Tests UL Standard 162 U.S. Military Specification TEST RESULTS FAA Tests Laboratory and Small-scale Tests Large-scale Tests NRL Tests Other Fire Tests CORRELATION BETWEEN SMALL- AND LARGE-SCALE FIRE TEST RESULTS Small-scale Test Parameters and Variables Correlation Between MIL SPEC Fire Tests and Large-scale Fires ADDITIONAL PARAMETERS FOR FOAM SPECIFICATIONS v Page xi 1 1 2 2 2 3 6 12 15 15 18 20 21 23 26 26 26 30 31 33 34 34 42 47 US00006734 CONCLUSIONS RECOMMENDATIONS REFERENCES 48 49 50 APPENDICES A - Comparison of the Physical and Chemical Properties of Protein-based and Aqueous Film-forming Foams B - Summary of NRL Tests C - Small- and Large-scale Test Data LIST OF ILLUSTRATIONS Figure Page 1 Fire Control Time as a Function of Solution Application Rate Using Protein Foam and AFFF 4 2 Fire Control and Extinguishing Times as Functions of the Foam Solution Application Rate Using Manufacturer A 's AFFF Agent at 250 and 400 gal/min on JP-4, JP-5, and AVGAS Fires 7 3 Fire Control and Extinguishing Times as Functions of the Foam Solution Application Rate Using Manufacturer B's AFFF Agent at 250 and 400 gal/min on JP-4, JP-5, and AVGAS Fires 8 4 Fire Control and Extinguishing Times as a Function of Solution Application Rate Using AFFF at 250, 400, and 800 gal/min on 8000 ft2 JP-4 Fuel Fires 9 5 Fire Control Time as a Function of Solution Application Rate for AFFF, Fluoroprotein, and Protein Foams for Jet A Fuel Fires 10 6 Relationship of Various Types of Foam Agents with Respect to Fluorosurfactant Content, Film Formation Capabilities, and Dry Powder Compatibility 13 7 Typical AFFF Fluorosurfactant Molecule 14 8 Summary of 50ft2 (4.6m2) Fire Tests, from FAA Tests211 29 vi US00006735 9 Fire Control Time for Large-scale Fire Tests of FFFP and AFFF 10 AFFF Control Time as a Function of Application Rate 11 Specific Control Times for AFFF at low Application Rates 12 Specific Control Times for AFFF at Intermediate Application Rates 31 44 45 46 LIST OF TABLES Table 1 Summary of the Fire Control Times Using the B-47 Aircraft 2 Summary of Fire Test Data for Applying Aqueous Film-forming Foam Through Air Aspirating and Nonair-aspirating Nozzles 3 Results of Airport Fire Department Foam Use and Specification SURVEY 4 Examples of International Specification Tests for Foam 5 ICAO Foam Test Requirements 6 Maximum Extinction Times and Minimum Bumback Times From Proposed ISO Specification 7 Foam Application Rates and Torch Exposure Times in UL 162 for Hydrocarbon Fuels 8 Summary of the U.S, Military AFFF Specification (MIL-F-24 85, Revision F) Key Performance Requirements 9 Physical/Chemical Properties and Procurement Requirements of the AFFF MIL SPEC 10 Fire Performance of AFFF Concentrates on MIL SPEC 50 ft2 (4.6 m2) Fire Test Conducted by FAA 11 Fire Performance of Film-forming Concentrates Conducted by FAA 12 Fire Performance of Fluoroprotein Foam Concentrates Conducted by FAA 13 Fire Performance of Protein Foam Concentrates Conducted by FAA vii Page 5 11 17 18 19 20 22 24 25 27 28 28 28 US00006736 14 Foam Quality for Large-scale AFFF/FFFP Tests 15 Summary of Hose Reel Fire Test Data from SRDB29 16 Summary of Fire Test Data from FRDG30 17 Variables Associated with Foam Performance and Testing 18 Examples of Extinguishment Application Densities of Various Test Standards 32 35 36 37 40 viii US00006737 LIST OF ABBREVIATIONS AND SYMBOLS AC AFFF ARFF CFR FAA FFFP FM FP FPF FRDG ICAO ISO MIL SPEC NFPA NRL PF PKP QPL SC SRDB UL Advisory Circular Aqueous Film-forming Foam Aircraft Rescue and Firefighting Crash Fire Rescue Federal Aviation Administration Film Forming Fluoroprotein Factory Mutual Fluroprotein Fluoroprotein Foam Fire Research and Development Group International Civil Aviation Authority International Standards Organization Military Specification National Fire Prevention Association Naval Research Laboratory Protein Foam Purple K Powder Qualified Products List Spreading Coefficient Scientific Research and Development Branch Underwriters Laboratories, Inc. IX US00006738 EXECUTIVE SUMMARY Federal Aviation Administration (FAA) and National Fire Protection Association (NFPA) primary foam agent requirements are based on the inherent philosophy that hydrocarbon fuel spill fires resulting from survivable aircraft crashes must be rapidly controlled and extinguished. This time frame, measured in seconds, includes notification, emergency response, and time to control/extinguish the fire. Success is based on the ability to limit this total response/suppression time to less than the time required for safe evacuation, which is primarily a function of the time to fuselage burnthrough when the crash airplane is intact. Through large-scale testing and estimates of potential spill sizes as a function of aircraft size, minimum agent quantities and application rates have been established. For Aqueous Film-Forming Foam (AFFF), these quantities were based on FAA large-scale tests where Military Specification (MIL SPEC) Qualified Products List (QPL) agents or agents submitted for QPL evaluation were used. The 0.13 gpm/ft2 (5.5 Lpm/m2) application rate was based on these AFFF agents. Foams which are candidates for this application rate should be judged using this criteria. A review of standard test methods and performance criteria indicates a wide range of requirements. Variations in test size, application rate, fuel, and nozzle placement make comparison between methods extremely difficult. Given these variations, it becomes difficult to judge agents based on a simple measure of performance and extinguishment application density. It was shown that the MIL SPEC, using a low flashpoint fuel and the lowest application rate of any test standard reviewed, requires the least amount of agent for extinguishment. The extinguishment application density for the International Civil Aviation Authority (ICAO), Underwriters Laboratories, Inc. (UL), and International Standards Organization (ISO) standards are respectively 2, 4, and 6 times that required for the MIL SPEC. The MIL SPEC is also explicit in its requirement that agents be a film former; other methods, with the notable exception of ICAO, now recognize the appropriateness of this requirement by including similar criteria. No direct correlation, however, has been established between chemical/physical properties criteria in the MIL SPEC and the fire extinguishment and burnback characteristics. It has been demonstrated, using comparative data from the FAA and specific control time data from numerous fire tests, that criteria from the small-scale MIL SPEC AFFF tests correlate with large-scale data. Agents which meet the small-scale test criteria are able to meet NFPA and FAA control-time requirements at less than the design application rate. The limited data available suggest that agents that fail to meet the MIL SPEC criteria may not provide this same factor of safety. Given the basis of the FAA criteria (tests with QPL agents) and the critical time frames involved in ARFF operations (1-3 minutes to respond, 60 seconds to control the spill fire), this safety factor is entirely appropriate as a basis for minimum FAA certification. The relevance of physical and chemical property tests in the MIL SPEC to ARFF applications has been well established over the years through testing designed to improve the MIL SPEC. These tests assure that AFFF has desirable attributes related to accurate proportioning, storage, stability, and shelf life in addition to minimum performance characteristics when used with other agents and when misproportioned. For FAA certification, one alternative would be to specify minimum fire performance requirements only. The risk is that QPL agent formulations may be modified, which might affect the overall impact of foam quality, e.g., half-strength performance, interagent compatibility, and Purple K xi US00006739 Powder (PKP) compatibility. A change in baseline agent performance would require reestablishment of the correlations demonstrated in this analysis, including large-scale testing. As a practical matter, it has been demonstrated that the majority of large airports already reference the MIL SPEC. For smaller airports, there may be some cost impact in referencing the entire MIL SPEC. However, it is precisely at these airports, with their limited equipment and training resources, where the factor of safety inherent in the MIL SPEC may be most important when it comes to an actual survivable aircraft crash incident. The proliferation of standard test methods and various criteria for foams has not yielded significant benefits in our understanding of fundamental foam extinguishing mechanisms. This is shown by the lack of one-to-one correlation of specific tests (e.g., film formation, expansion, drainage, spreading coefficient, and fluorine content) with extinguishment and bumback performance. It is apparent that a single valid test method or combination of methods to evaluate all types of foam have yet to be developed. While a single test might be used, the variables involved leads to no clear correlatable distinction between individual foams and differences between foam types. This is another endorsement for adoption of the MIL SPEC for AFFF; it is, to date, the method with the best data to correlate results between small- and large-scale for the application of interest, FAA certification of primary agents at critical application rates. It is recommended that the FAA adopt the MIL SPEC in its entirety as criteria for accepting foam agents used at the 0.13 gpm/ft2 (5.5 Lpm/m2) application rate. The UL 162 standard type 3 application test is adequate for agents used at the higher application rate of 0.20 gpm/ft2 (8.2 Lpm/m2) for fluoroprotein foam (FPF). Any future work related to foam testing should focus on the use of first principles to establish fundamental foam extinguishment mechanisms. The goal should be to correlate and use benchscale results to predict large-scale performance. xu US00006740 BACKGROUND Firefighting foams are the primary agents used at airports to combat fuel fires resulting from aircraft incidents, In the United States, the Federal Aviation Administration (FAA) certifies airport operations, including aircraft rescue and firefighting (ARFF) capabilities. Guidelines for facilities and agents are given in Advisory Circular (AC) 150/5210-6C, "Aircraft Fire and Rescue Facilities and Extinguishing Agents"1. Minimum quantities of agents are described, both in terms of total quantities and rates of application. Protein foams (PF) are required to be applied at 0.20 gpm/ft2 (8.2 Lpm/m2) while aqueous film-forming foams (AFFF) must be applied at 0.13 gpm/ft2(5.5 Lpm/m2). This difference in application rate recognizes the inherent advantage of using AFFF in extinguishing hydrocarbon pool fires; AFFF has been demonstrated to extinguish pool fires more rapidly than protein foams at equivalent application rates2. For equivalent extinguishment times, lower rates of AFFF are required compared to protein foams. The National Fire Protection Association Standard 403, "Standard for Aircraft Rescue and Fire Fighting Services at Airports3," recognizes an application rate of 0.18 gpm/ft2 (7.2 Lpm/m2) for fluoroprotein foam (FPF). The number and types of firefighting foams offered to FAA certified airports have proliferated. The distinction between foam types has been blurred with the introduction of fluoroprotein, film-forming fluoroprotein (FF'FP), and alcohol-resistant foams. Airports require technical guidance for selecting appropriate agents. Currently, the FAA advisory circular only provides general guidance, e.g., Section 24 of AC 150/5210-6C: " . . . While it is recognized that acceptance testing of extinguishing agents is necessary, the technical characteristics, quality, stability, compatibility, etc., cannot be determined during such system tests or demonstrations. Therefore, the airport management should request that prospective bidders and suppliers of fire-extinguishing agents furnish indication of tests on performance and quality by a recognized laboratory." The situation was further complicated when Underwriters Laboratories, Inc. (UL) approved FFFP as both a fluoroprotein and an AFFF agent in their listings. They have subsequently removed aircraft firefighting from the scope of their test standard, UL 1624. Certified airports must now individually determine the standard of performance to invoke when purchasing foam agents. The performance should relate to the level of safety established by the required foam application rates. Since large-scale fire testing by each individual airport is no longer a viable means of evaluation, smaller scale test methods must be utilized. The test method should demonstrate correlation with the large-scale test methods used to establish the baseline application rates. The referencing of a standard test method should also provide a degree of quality control in the purchase of agents which have demonstrated appropriate fire performance capability. OBJECTIVE The objective of this report is to document and analyze the existing data on the performance of foam agents. Based on this analysis, a technically based performance standard for commercial airport foam requirements is to be recommended for inclusion in an FAA Advisory Circular, 1 US00006741 APPROACH In order to identify appropriate foam standards, the basis for the foam application rates was identified. These application rates are based on the ability to control a fire before passengers in a survivable post crash incident are threatened by an exterior pool fire. Having established the basis of the requirements, a review of test data was performed to identify important foam parameters. These data are drawn largely from FAA and Naval Research Laboratory (NRL) tests and evaluations. Test standards used in the United States and other countries were identified, including methods currently used by large U.S. airports. Using the large-scale data and small-scale test methods, an attempt was made to demonstrate correlation between small- and large-scale results. This includes data related to the issue of equivalency of FFFP with AFFF. Based on the analysis, recommendations were developed for adopting a standard method/criteria in the advisory circular and for performing additional research to develop a more technically sound method to determine important foam parameters. HISTORICAL BASIS FOR FOAM REQUIREMENTS THE SURVIVABLE POST-CRASH AIRCRAFT ACCIDENT. A substantial amount of work has been conducted on the effects of pool fires on aircraft fuselages. The underlying principle is to temporarily maintain the integrity of an aircraft fuselage to allow passenger escape or rescue. Lindemann5 has summarized the critical times for passenger survivability. When an aircraft is involved in a fuel spill fire, the aluminum skin will bumthrough in about one minute. If the fuselage is intact, the sidewall insulation will maintain a survivable temperature inside the cabin until the windows melt out in approximately three minutes. At that time, the cabin temperature rapidly increases beyond survivable levels. References 6, 7, and 8 provide additional research on the fuselage integrity issue. ARFF vehicles are designed to reach an accident scene on the airport property in two to three minutes, depending on the standard enforced by the authority having jurisdiction. Having reached the scene in this time frame, the extinguishing agent must be applied to control a fire in one minute or less. The oneminute critical time for fire control is recognized by FAA, National Fire Prevention Association (NFPA), and the International Civil Aviation Authority (ICAO). Minimum agent requirements on ARFF vehicles are established using the one-minute critical control time plus the anticipated spill area for the largest aircraft using the airport. A "theoretical critical fire area" has been developed, based on tests, which is defined as the area adjacent to the fuselage, extending in all directions to the point beyond which a large fuel fire would not melt an aluminum fuselage regardless of the duration of the exposure. Considering the function of the size of an aircraft, the theoretical critical fire area was refined to a practical critical fire area after the evaluation of actual aircraft fire incidents indicated that less agent was being used than the amounts developed from the theoretical fire area9. The practical critical area, two-thirds the size of the theoretical critical area, is widely recognized by the aviation fire safety community, including FAA, NFPA, and ICAO. Vehicles must be equipped with sufficient agent and discharge devices to control a fire in the practical critical area within one minute. 2 US00006742 CRITICAL APPLICATION RATES. Tests were conducted by the FAA to determine application rates for a single-agent attack to achieve fire control (e.g., 90 percent extinguishment of a fire area) within one minute under a wide variety of simulated accident conditions. Two concepts are important in addition to the application rate required for one-minute fire control: the critical application rate, below which fires will not be extinguished independent of the amount of time agent is applied; and application density, which is the amount of foam per unit area required to control or extinguish a fire. Numerous fire tests were conducted in an attempt to quantify the important foam parameters. The basis for the current minimum application rates were originally developed by Geyer in tests of protein and AFFF agents7. These tests involved Mmodeling,' tests with JP-4 pool fires of 70, 100, and 140 ft (21, 30, and 43 m) diameter. Large-scale verification tests with a B-47 aircraft and simulated shielded fires (requiring the use of secondary agents) were conducted with 110 and 140 ft (34 and 43 m) JP-4 pool fires. All tests were conducted with air-aspirating nozzles. The protein foam conformed to the Federal Specification, 0-F-555b10, while the AFFFs used were in nominal conformance with the Military Specification for AFFF. These tests were being performed at the time when the seawater compatible version of the AFFF MIL SPEC11had just been adopted based on large-scale tests12. The draft seawater AFFF specification described in reference 12 is the "father" of the current version of the MIL SPEC, MIL-F-24385 Rev. F13. Figure 1 shows the results of the "modeling" experiments. This shows that, for a control time of 60 seconds, the application rate for AFFF was on the order of 0.04 - 0.06 gpm/ft2 (1.6 - 2.4 Lpm/m2) while the application rate for protein foam was 0.08 - 0.10 gpm/ft2 (3.3 - 4.1 Lpm/m2). The data indicate that the application rate curves become asymptomatic at rates of approximately 0.1 gpm/ft2(4.1 Lpm/m2) and 0.2 gpm/ft2 (8.2 Lpm/m2) for AFFF and protein foam respectively. Above these rates, fire control times would not appreciably improve. Likewise, critical application rates for fire control are indicated when control times increase dramatically. The single test with a fluoroprotein agent indicated that this agent, as expected, fell between AFFF and protein foam. The large-scale auxiliary agent tests were conducted to identify increases in foam required when obstructed fires with an actual fuselage were added to the scenario. The results, shown in table 1, indicated that fire control times increased by a factor of 1 to 1.9 for AFFF and 1.5 to 2.9 for protein foams. It was estimated that the most effective foam solution application rates were 0.12 - 0.14 gpm/ft2 (4.9 - 5.7 Lpm/m2) for AFFF and 0,18 - 0.22 gpm/ft2 (7.5 - 9 Lpm/m2) for protein foam. This is the original basis of the recommendations adopted by ICAO9 of 0.13 gpm/ft2 (5.5 Lpm/m2) for AFFF and 0.20 gpm/ft2 (8.2 Lpm/m2) for protein foam. These values are still used by the FAA, NFPA, and ICAO. When multiplied by the practical critical fire area, they form the basis of minimum foam flow rates and water requirements on Crash Fire Research (CFR) vehicles. 3 US00006743 120 100 80 60 40 20 0 -- !-----------1---------- ,---------- 1---------- ,---------- 1---------- 1-----------1-----------1-----------1---------- 1----------- 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0. Solution Application Rate (gpm/ft2) FIGURE 1. FIRE CONTROL TIME AS A FUNCTION OF SOLUTION APPLICATION RATE USING PROTEIN FOAM AND AFFF TABLE 1. SUMMARY OF THE FIRE CONTROL TIMES USING THE B-47 AIRCRAFT Equipment Approach Fire Diameter (ft (m)) Solution Rate (gpm (Lpin)) Solution Application Rate (gpm/ft2 (Lpm/nr) Dispensing Equipment Foam Agent Fire Prehurn Time - s Fire Control Time After Ignition - s Average Fire Control Time After Ignition - s Fire Control Time After Start of Foam - s Average Fire Control Time After Foam - s Fire Damage to Fuselage Skin Control Time of Equivalent Pool Fires - s Test 1 Starboard Port Rear 140 (43) 140 (43) 780 (2950) 780 (2950) 0.10 (4 1) 0.10 (4.1) Nozzle B AFFF 22 76 front 68 rear 70 Nozzle B AFFF 19.5 55 front 54 rear 54.5 50 front 45 rear 48 35.5 front 34.5 rear 35 Severe 23 Very minor 23 Test 2 Starboard Port Rear 140 (43) 140 (43) 780 (2950) 780 (2950) 0.10 (4.1) 0.10 (4.1) Nozzle B Protein 35 80 front 80 rear 80 Nozzle B Protein 25 none none 45 front 45 rear 45 none none Severe 40 Severe 40 Test 3 Starboard Port Rear 110 (34) 110 (34) 496 (1880) 530 (2010) 0.10 (4.1) 0.11 (4.5) Nozzle A AFFF 15 47 front 33 rear 40 Foam Pump AFFF 15 58 front 43 rear 50.5 22 front 18 rear 25 43 front 28 rear 35.5 Minor 34 Severe 30 Test 4 Starboard Port Rear 110(34) 110 (34) 496 (1880) 530 (2010) 0.10 (4.1) 0.11 (4.1) Nozzle A Protein 25 180 front 180 rear 180 Foam Pump Protein 25 145 front 140 rear 142.5 155 front 155 rear 155 120 front 115 rear 117.5 No data 55 No data 38 Tests of AFFF alone were conducted by Geyer14. These agents, which were selected from the U.S. Qualified Products List (QPL) (MIL SPEC requirements), were tested on JP-4, JP-5, and aviation gasoline fires. Air-aspirating nozzles were used. The results are shown in figures 2 and 3. Similar data were collected by holding the JP-4 fuel fire size constant at 8000 ft2 (743 m2) and varying the flow rates to develop application rate comparisons. These data are shown in figure 4. The data show that Foam A is more effective than Foam B at lower application rates. Additional tests were conducted by Geyer to verify the continuation of the reduction of water when AFFF agents were substituted for protein foam15. In 82.4-, 101-, and 143-ft (25, 31, and 44 m)-diameter Jet A pool fires, AFFF, fluoroprotein, and protein foams were discharged with aspirating and nonair aspirating nozzles. Three and six percent concentrates were used. The six percent concentrates were manufactured in accordance with the MIL SPEC in force at the time. The three percent concentrates were not manufactured to the MIL SPEC since three percent concentrations were not yet included in the MIL SPEC. The data, summarized in figure 5, validated the continued allowance of a 30 percent reduction in water requirement at certified U.S. airports when AFFF is substituted for protein foam. A minimum application rate of 0.05 gpm/ft2 and 0.10 gpm/ft2 (2.0 and 4.1 Lpm/m2) were identified for AFFF and PF/FPF respectively for controlling Jet A fires. This is consistent with earlier work. The data showed that nonair-aspirated AFFF was more effective at critical application rates than air-aspirated AFFF. This was verified by Jablonski16 in tests with Air Force crash trucks as shown in table 2. SUMMARY AND KEY FACTORS. The historical test data clearly supports the philosophy that AFFF can be applied at rates lower than protein and fluoroprotein foams. Large-scale tests were used to develop the required application rates needed for critical one-minute fire control. Where these tests used AFFF, the agents were from the QPL or the agents were in nominal conformance with the MIL SPEC, e.g., a developmental agent formulated to meet a new revision of the MIL SPEC. MIL SPEC AFFF forms the basis of the current FAA, NFPA, and ICAO criteria for reduced application rates and agent quantities. The Montreal ICAO Panel9pointed out that quantities of agent required to extinguish actual aircraft fires are normally greater than those for test and training fires for a variety of reasons. They identified the problems of scaling from small to large scale, the training of the firefighting personnel, inaccessibility of some fire areas, initial overuse of foam, the three-dimensional nature of aircraft fires, and difficulties in deployment and control. Geyer has also identified wind as a factor. It is appropriate then, that any standard specifying foam products have a factor of safety. This is usually accomplished by having tests meet fire performance and bumback requirements at critical application rates, i.e., at rates below the rate at which increases provide insignificant benefits. For AFFF, rates above 0.10 gpm/ft2 (4.1 Lpm/m2) may not provide any significant benefit in terms of substantially decreased control times. Critical rates for AFFF are on the order of 0.03 - 0.05 gpm/ft2 (1.2 - 1.6 Lpm/m-). The issue is to select a test method which provides screening of good and poor products and establishes a factor of safety appropriate for aviation applications. The appropriate safety factor is dependent on the application. For combustible liquid and tank farm applications, which the UL Standard is geared towards, a fire incident may last days. The fire control time may not be critical compared to the need to provide extended bumback resistance. This compares to the seconds required for control of an 6 US00006746 80 (QD c o0 S2. 60 E F D) C IE > 40 c 1 co o ~ 20 o O ix. Fuel JP-4 Solution R at* 2S0 gal/m ln Fire C ontrol Time I Flre-Extingulshlng Time Solution Rate 400 gal/m ln S. Fire C ontrol Time A Flre-Extingulshlng Time Fuel JP-5 Solution Rate 260 gal/m ln O Fire C ontrol Time 9 Flre-Extingulshlng Time Solution Rate 400 gal/m ln \ 7 Fire C ontrol Time y Flre-Extingulshlng Tbne Fuel AVGAS Solution Rate 260 gal/m ln O Fire C ontrol Time ^ Flre-Extingulshlng Time S olution Rate 400 gal/m ln O Fire C ontrol Time t Flre-Extingulshlng Time TT 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 Solution Application Rate (gal/min/ft2) FIGURE 2. FIRE CONTROL AND EXTINGUISHING TIMES AS FUNCTIONS OF THE FOAM SOLUTION APPLICATION RATE USING MANUFACTURER A 'S AFFF AGENT AT 250 AND 400 GAL/MIN ON JP-4, JP-5, AND AVGAS FIRES Fuel JP-4 Solution Rats 2S0 g a ttn ln I I F ir* C ontrol Time Fir-Extinguishing T im S olution Rate 400 gal/min A Fire C ontrol Time A Flre-Extlnguishlng Time Fuel JP-S S olution Rate 260 gal/m in O Fire C ontrol Time 0 Flre-Extlogulshlng Time Fuel AVGAS Solution Rote 260 gal/m in <Q> Fire C ontrol Time 4 FIre-E xtinguishing Time T(A3 Co001 CO t0o) E |ca> to '5 Oc) LKU o C(0 co o iZ 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Solution Application Rate (gal/min/ft2) 0.14 0.16 FIGURE 3. FIRE CONTROL AND EXTINGUISHING TIMES AS FUNCTIONS OF THE FOAM SOLUTION APPLICATION RATE USING MANUFACTURER B 'S AFFF AGENT AT 250 AND 400 GAL/MIN ON JP-4, JP-5, AND AVGAS FIRES  Control Time - Agent A O Fire-Extinguishing Times - Agent A Control Time - Agent B Fire-Extinguishing Times - Agent B FIGURE 4. FIRE CONTROL AND EXTINGUISHING TIMES AS A FUNCTION OF SOLUTION APPLICATION RATE USING AFFF AT 250, 400, AND 800 GAL/MIN ON 8000 FT2JP-4 FUEL FIRES 60 Air-asoiratina foam nozzle AEFF o FC - 203 50 0 FC - 206 Fluoroorotein XL-6 V XL-3 Protein foam 40 o TYPE O - F - 655C A AER O - FOAM 3 Non air-esoiratina water nozzle AEEE 30 FC - 203 FC - 206 20 10 Fire size Fire size Fire size 16,000 ft* 8,000 ft* 6,333 ft1 0 ----- !----------------------------------1----------------------------------1--------------------------------- 0.05 0.10 0.15 0. Foam solution application rate gal/min/ft^ IRE 5. FIRE CONTROL TIME AS A FUNCTION OF SOLUTION APPLICATION RATE FOR AFFF, FLUOROPROTEIN, AND PROTEIN FOAMS FOR JET A FUEL FIRES TABLE 2. SUMMARY OF FIRE TEST DATA FOR APPLYING AQUEOUS FILM-FORMING FOAM THROUGH AIR-ASPIRATING AND NONAIR-ASPIRATING NOZZLES Fire Control 90 Percent Extinguishment Burnback Aircraft Test Mockup Nozzle AFFF Solution Rate (gpm (Lpm)) Time (s) Density (gal/ft2 (17m2)) Time to 25 Percent (min) Density (gal/ft2 (Dm 2)) Phase I --250 gpm (946 Lpm) Air-aspirating and Non Air-aspirating Nozzles (MB-1 vehicle) on 4000 ft2 (372 m2) JP-4 Fuel Fires 1 No Air-aspirating 260 (984) 31 0.033 (1.3) 12.3 0.059 (2.4) 2 No Air-aspirating 267 (1010) 28 0.031 (1.3) 16.6 0.063 (2.6) 3 No Nonair-aspirating 263 (995) 22 0.024 (0.98) 11.2 0.063 (2.6) 4 No Nonair-aspirating 241 (912) 18 0.018 (0.73) 14.0 0.055 (2.2) 5 Yes Air-aspirating 252 (954) 27 0.028 (1.1) 11.7 0.058 (2.4) 6 Yes Air-aspirating 239 (905) 31 0.031 (1.3) 13.8 0.059 (2.4) 7 Yes Nonair-aspirating 240 (908) 23 0.023 (0.94) 21.0 0.056 (2.3) 8 Yes Nonair-aspirating 232 (878) 21 0.020 (0.81) 17.7 0.056 (2.3) Phase II --Fire Test Data for Applying Aqueous Film-forming from 750 to 800 gpm (2839 to 3028 Lpm) Air-aspirating and Nonair-aspirating Nozzles on 8000 ft2 (2440 m2) JP-4 Fuel Fires 9 No P-4 Air-aspirating 711 (2690) 37 0.055 (2.2) 15.5 0.121 (4.9) 11 No P-4 Air-aspirating 671 (2540) 39 0.055 (2.2) 21.0 0.095 (3.9) 10 No P-4A Nonair-aspirating 819 (3100) 40' 0.068' (2.8) 14.0 0.128 (5.2) 12 No P-4A Nonair-aspirating 804 (3040) 27 0.045 (1.8) 18.0 0.116 (4.7) 13 Yes P-4 Air-aspirating 715 (2710) 35 0.052 (2.1) 14.3 0.090 (3.7) 16 Yes P-4 Air-aspirating 739 (2800) 34 0.052 (2.1) 12.8 0.120 (4.9) 14 Yes P-4A Nonair-aspirating 823 (3120) 23 0.039 (1.6) >28b 0.105 (4.3) 15 Yes P-4A Nonair-aspirating 840 (3040) 23 0.040 (1.6) 16.5 0.107 (4.4) ' Equipment malfunction - water only for initial 20-second application b Wind conditions affected test results aviation incident -- a difference of several orders of magnitude compared to tank farm incidents. Differences in agent performance measured in seconds, which may normally be disregarded, have to be considered for aviation incidents. The next sections describe different foam agents and address the issues of appropriate test standards, the meaning of small-scale test variables, the correlation of small- and large-scale tests, and the appropriate approach the FAA should pursue. DESCRIPTION OF AGENTS. As described in the previous section, foam agents were tested in large scale to develop extinguishing application rates and quantities. Fluoroprotein foams were assigned an application rate between AFFF and protein foam by NFPA. The development of new foams, particularly FFFP and alcohol-resistant foams, do not necessarily fit in the standard categorization of AFFF, protein, or fluoroprotein foams. This raises the question of where new formulations should fit in the application rate requirements. An understanding of the composition of foam agents is fundamental to an evaluation of the issue. Geyer et al.15 having described the composition of various foam agents, paraphrased as follows: Protein Foam (PF) --protein foam is a "mechanical" foam produced by combining (proportioning) foam concentrate and water at specific ratios. The resulting solutions are then discharged through a mixing chamber. The mixing chamber introduces (aspirates) air which expands the solution to create foam bubbles. The liquid concentrate consists primarily of hydrolyzed proteins in combination with iron salts. Hoof and horn meal, and hydrolyzed feather meal are examples of proteinaceous materials used in protein foam concentrates. When applied to a hydrocarbon fuel surface, the foam bubbles act to exclude the air from the fuel vapors, effectively preventing the creation of a combustible mixture. The bubbles also contain water to cool the fuel and attendant hot surfaces. No aqueous Film is formed on the fuel surface with this type of agent. Fluoroprotein (FPF) - these agents are basically protein foams with fluorocarbon surface-active agents added. The varying degrees of performance are achieved by using different proportions of the base protein hydrolyzates and the fluorinated surfactants. While fluoroprotein foams generally have good fuel shedding capabilities and dry chemical compatibility, the solution which drains out from the expanded foam does not form a film on hydrocarbon fuels. However, the addition of the fluorinated surfactants may act to reduce the surface tension of the solution. This reduction may in turn decrease the viscosity of the expanded solution, thus promoting more rapid Fire control when compared to protein foams. FFFP - these agents are also based on protein foam formulations. They are produced by increasing the quantity and quality of the fluorocarbon surfactants added to the protein hydrolyzate. By doing this, the surface tension of the resulting solution which drains from the expanded foam is reduced to the point where it may spread across the surface of a liquid hydrocarbon fuel. Under these conditions, the agent may still be termed a "fluoroprotein" foam, but the physical and Fire extinguishing characteristics are similar and perhaps even equal to those of an AFFF (Figure 6). 12 US00006752 No Fluorosurfactants 4 Present Increasing Amounts of Fluorosurfactants Present Protein Foam --------- 1--------- l l l No Aqueous Film Formed; No Dry Powder Com patibility Fluoroproteln Foam 44 --------- 1----------------- l l I No Aqueous Film Formed; Dry Powder Com patibility FFFP i 1 1 1 44 May Form An Aqueous Film Dry Powder Com patibility AFFF l 1 1 1 Aqueous Film Formed Dry Powder Com patibility FIGURE 6. RELATIONSHIP OF VARIOUS TYPES OF FOAM AGENTS WITH RESPECT TO FLUOROSURFACTANT CONTENT, FILM FORMATION CAPABILITIES, AND DRY POWDER COMPATIBILITY  AFFF - these agents are synthetically formed by combining fluorine free hydrocarbon foaming compounds with highly fluorinated surfactants. When mixed with water, the resulting solution achieves the optimum surface and interfacial tension characteristics needed to produce a film which will spread across a hydrocarbon fuel. The foam produced from this agent will extinguish in the same water cooling and vapor-excluding fashion as other foams. However, the solution which results from normal drainage or foam breakdown will quickly produce an aqueous "film" which spreads rapidly and is highly stable on the liquid hydrocarbon fuel surface. It is this film formation characteristic which is the significant feature of AFFFs. These descriptions show that there are distinct chemical differences between protein based foams and AFFFs. The formulation of an FFFP may imply a simple mixing of a fluoroprotein agent with an AFFF. In fact, informal experiments have been performed where AFFFs were mixed with protein based foams1718. The investigators found that this simplification ignores the chemical compatibility and synergistic effects of combined agents. For example, the source and proportions of proteinaceous materials in protein type foams is very important. Mixing protein based materials with AFFF may, under certain conditions, result in hydrolysis, deactivation of the protein, or a change of pH. While both investigators were able to achieve favorable results by mixing agents in the laboratory, neither recommend the practice for actual firefighting agents. Fiala18 indicated that this procedure is "believed to be of no importance for practical use." In general, the surfactants used in aqueous foams are long chained compounds which have a hydrophobic (water hating or water insoluble) group at one end and a hydrophilic (water loving or water soluble) group at the other end19. The molecular structure of a typical AFFF fluorinated surfactant is shown in figure 7. In this molecule, the perfluorooctyl group on the left is the hydrophobic group, while the propyltrimethylammonium group is the hydrophilic group. When these compounds are dissolved into solution with water, they will tend to group near the surface o f the solution and aligned so that their hydrophobic ends are facing towards the air/solution interface. The advantage of this is that the perfluorooctyl group found in these compounds is oliophobic (oil or hydrocarbon insoluble) as well as hydrophobic20. FF FFF FF F CH, "+ 11111 111 1 C - C - - C - - C - - C - - C - - c - s o 2 N (CH,) j - N - C H , 1* 11 1 11111 1 FFFFFFFF --1 r> X O r 0 1 1L FIGURE 7. TYPICAL AFFF FLUOROSURFACTANT MOLECULE 14 US00006754 AFFF concentrates also contain hydrocarbon surfactants. These compounds are less hydrophobic than those containing the perfluorooctyl group21. However, they do provide greater stability once the solution is expanded into a foam. The net result of combining both of these compounds in an aqueous solution is that the surface tension of the solution is reduced below that of water; the expanded foam produced from the solution is resistive to breakdown from heat, fuels, or dry chemical extinguishing agents, and the solution which drains out from the expanded foam is able to form a film on hydrocarbon fuels. The importance of both the film formation and foam bubble characteristics of AFFF, resulting from the combination of fluorocarbon and hydrocarbon surfactants, was evaluated in early work by Tuve et al.22. When a highly expanded stiff formulation of AFFF was used, these experimenters found it difficult to obtain good fire extinguishment and vapor sealing characteristics because the foam resisted flow and drainage of the aqueous solution (film) was slow. This was corrected by reducing foam expansion. Foam agent with an expansion ratio of eight-to-one and a 25 percent drainage time of six minutes appeared to offer the best compromise in characteristics. It provided a readily flowable foam which sealed up against obstructions, promoted the rapid formation of a surface-active film barrier on the fuel, and provided a sufficiently stable foam to resist bumback. Chemical composition is vital in achieving a balanced formulation. This formulation must create a stable foam bubble which will, over time, release an aqueous solution with the ability to form a vapor suppressing film on hydrocarbon fuels. The introduction of FFFP is yet another chemical variant of the essential balanced formulation. Because foam matrix stability is also affected by the degree of aspiration of the foam solution, the continuing conflict over foam aspiration is naturally a related issue. Having identified that chemical composition and foam quality are important factors in the equivalence debate, the issue can be simplified to one of fire performance capabilities. The best agent is the one that controls and extinguishes hydrocarbon fuel fires the fastest and provides the greatest degree of resistance to bumback. If agents are similar in terms of these fire performance criteria, then the user must judge if the other differences are important. This assumes that other operational requirements are met, e.g., the compatibility of the agent with CFR equipment and auxiliary agents. STANDARDS AND REGULATIONS NATIONAL STANDARDS AND TEST METHODS. Given the differences in chemical composition between agents, how does the user select an agent? In the United States, the primary method of selecting agents is by reference to an UL listed product23 or in the case of AFFFs, reference to the military specification, M IL-F-2438513. It was noted in the Background Section that the FAA does not have specific test criteria for foam agents. The NFPA Standards and Recommended Practices related to aviation are contained in the following documents: NFPA 402M - Manual for Aircraft Rescue and Firefighting Operational Procedures (1989 Edition). NFPA 403 - Standard for Aircraft Rescue and Firefighting Services at Airports (1993 Edition). 15 US00006755  NFPA 4 1 2 - Standard for Evaluating Aircraft Rescue and Firefighting Foam Equipment {1993 Edition). NFPA 414 - Standard for Aircraft Rescue and Firefighting Vehicles (1984 Edition). These four standards are all closely related and in fact reference each other in many cases. NFPA 403 is the reference document in terms of foam requirements for crash, firefighting, and rescue operations. The CFR requirements in NFPA 402M, 412, and 414 are derived from NFPA 403. It is NFPA 403 which defines the minimum requirements for airport CFR services. Airports are categorized by the maximum size of aircraft serviced. The amount of apparatus and the minimum total extinguishing agent flow rate is then defined based on this categorization. Acceptable types and quantities of agents are described. These rates and quantities are based on the "critical fire area" concept described in the Historical Basis section. The membership of NFPA recently voted to adopt fire test criteria for primary extinguishing agents (foam) in NFPA 403. These new requirements and the rationale for adopting the test method are described in the correlation section of this report. In order to determine the types of agents being used and methods of procurement, a survey of 24 major U.S. airports was conducted in 199024. All of these facilities are classified as Index 5-8 airports in accordance with NFPA 403. Essentially, these airports require the greatest degree of protection in terms of CFR vehicle capability and agent capacity. Fire department personnel and/or procurement specialists were asked what foam concentrate they had most recently purchased. They were also asked how the foam agent was specified, e.g., by UL listing, MIL SPEC approval, or commercial specification. The results of the survey are shown in table 3; complete details are contained in reference 24. The results of the survey were as follows: 1. All major airports use AFFF - 10 (42 percent) use 6 percent AFFF - 14 (58 percent) use 3 percent AFFF 2. Six airports (25 percent) supplement AFFF with another type of agent - 4 (17 percent) use fluoroprotein or protein foam - 2 (8 percent) use FFFP/Polar Solvent agents Boston Logan (Mass. Port. Auth.) uses Angus Tridol 6 percent, which is a UL listed AFFF; they also carry Angus Petroseal 6 percent, an unlisted FFFP, on their apparatus in 5 gal. cans San Diego uses both MIL SPEC AFFF and a UL listed dual-purpose agent (Angus Alcoseal, FFFP listed for use on both polar solvent and hydrocarbon fuels) 3. Fifteen (63 percent) reference the MIL SPEC 4. Five (21 percent) reference UL 16 US00006756 TABLE 3. RESULTS OF AIRPORT FIRE DEPARTMENT FOAM USE AND SPECIFICATION SURVEY1 Airport Location 1. Atlanta 2. BWI 3. Boston 4. Chicago O'Hare 5. Cincinnati 6. Cleveland 7, Dallas/Fort Worth 8. Denver 9. Detroit 10. Dulles 11. Houston (Intercontinental) 12. LAX 13. Las Vegas 14. Miami 15. Nashville 16. Washington National 17. New York Port Authority (JFK, Laguardia & Newark) 18. Philadelphia 19. Phoenix 20. San Diego 21. San Francisco 22. Seattle 23. St. Louis 24. Tampa AFFF 6 % X X X X X X X X X X Foam Type AFFF 3 % Fluoroprotein or Protein XX X X X X X X X X X X XX X X X X Other X X Specification MIL SPEC UL X X X X X X X X X XX X X Other X X X X X X X X X XX X XX X XX X X US00006757 J See Reference 24 lor notes to this table. 5 . Twelve (50 percent) use other methods in addition to or in lieu of MIL SPEC/UL requirements: - Four airports (17 percent) use their own spec (Chicago, Cincinnati, Houston and Philadelphia) - Four airports (17 percent) specify the manufacturer (Boston/MPA, Detroit, Tampa, and Nashville) - FAA, Factory Mutual (FM) and NFPA "requirements" were also cited The most significant finding was that the majority of the airports surveyed referenced the MEL SPEC. INTERNATIONAL STANDARDS. The number of international standards developed for foams is quite substantial. A brief review of the literature yielded over 17 different standards and test methods. These are summarized in table 4, While it is beyond the scope to individually review each document, it is important to note that most of the AFFF standards and specifications require either a film formation test and/or a positive spreading coefficient. Developments by the European community are reviewed here since they are some of the strongest proponents of FFFP. TABLE 4. EXAMPLES OF INTERNATIONAL SPECIFICATION TESTS FOR FOAM United States/North America UL 162 MIL-F-24385 OF 555 28GP74 (Canada) Europe DT 8188/STNA/DGCA (France) FRN-1007 (UK) Defence Standard 42-21 (UK) Defence Standard 42-24 (UK) Defence Standard 42-22 (UK) ICAO Annex 14/Airport Services Manual ISO (proposed) Defense Standard DIN 14-272 (Germany) Specification N.FS60201 (France) N O R D T E ST N T FIR E 023 (Finland/Sweden, e.g., Swedish Civil Aviation Administration) Others ! : DCA/F/2381 (Australia) W5FE 7508, Issue No. 2 (Australia) Defense Standards 5603A (Australia) Department of Aviation WS FF 7508 (Australia) AFFF Specification (Japan) AFFF Specification (India) Type of Foam All types AFFF Protein AFFF All types All types Protein AFFF Fluoroprotein All types All types AFFF AFFF and fluoroprotein All types Protein AFFF AFFF AFFF AFFF AFFF 18 US00006758 The ICAO develops crash firefighting and rescue documents for its member bodies. The Airport Services Guide, Part 1 Rescue and Firefighting (Third Edition, 1990) describes airport levels of protection to be provided (chapter 2) and extinguishing agent characteristics (chapter 8). Chapter 2, in describing minimum usable amounts of extinguishing agents, describes two levels of performance: Level A and Level B. The amounts of water specified for foam production are predicated on an application rate of 0.20 gpm/ft2 (8.2 Lpm/m2) for Level A and 0.13 gpm/ft2 (5.5 Lpm/m2) for Level B. Level B agents require less agent. Foam specifications are contained in chapter 8, table 8-1. These criteria are reproduced here as table 5. Foams meeting performance Level B have an extinguishment application density of 0.061 gai/ft2 (2.5 L/m2). Surface tension, interfacial tension, and spreading coefficient criteria in the previous edition of the Airport Services Guide have been deleted from table 8. TABLE 5. ICAO FOAM TEST REQUIREMENTS Fire Tests 1. Nozzle (air-aspirated) (a) Branch pipe (b) Nozzle pressure (c) Application rate (d) Discharge rate 2. Fire size 3. Fuel (on water surface) 4. Preburn time 5. Fire performance (a) Extinguishing time (b) Total application time (c) 25% reignition time Performance Level A "UNI 86" foam nozzle 100 psi (700 kPa) 0.10 gpm/ft2 (4.1 Lpm/m2) 3.01 gpm (11.4 Lpm) s30 ft2 (=2.8 m:) (circular) Kerosene 60 s < 60 s 120 s > 5 mm Performance Level B "UNI 86" foam nozzle 100 psi (700 kPa) 0.06 gpm/ft1 (2.5 Lpm/m:) 3.01 gpm (11.4 Lpm) =48 ft2 (=4.5 m2) (circular) Kerosene 60 s < 60 s 120 s > 5 min The International Organization for Standardization has issued a draft specification for low-expansion foams, ISO/DIS 7203 (1992).25 The specification includes definitions for protein, fluoroprotein, synthetic, alcohol resistance, AFFF, and FFFP concentrates. A positive spreading coefficient is required for film-forming foams when cyclohexane is used as the test fuel. There are toxicity, corrosion, sedimentation, viscosity, expansion, and drainage criteria. The fire test uses a 2.4-m-diameter circular pan with heptane as the fuel. The UNI 86 nozzle is used for either a ''forceful" or "gentle" application method at a flow rate of 3 gpm (11.4 Lpm). The application rate is 0.06 gpm/ft2 (2.4 Lpm/m2). For the greatest performance level, a three-minute extinguishment time is required. This results in an extinguishment application density of 0.19 gal/ft2 (7.6 Lpm/m2) The requirements for extinguishing and burnback are summarized in table 6. There are three levels of extinguishment performance and four levels of burnback performance. For extinguishing performance. Class I is the highest class and Class III the lowest class. For burnback resistance, Level A is the highest level and Level D the lowest level. Foam concentrates can be compared for each factor separately but not necessarily in combination. For example, a IC concentrate is superior to a ID or a 19 US00006759 IIC concentrate, but it is not possible to say that it is superior to a IIB concentrate since it is superior in extinguishing performance but inferior in burnback resistance. Typical performance classes and levels for different concentrates are provided. Typical anticipated performance for AFFF is noted as ID and for FFFP as IA/B. For alcohol resistant foams, both AFFF and FFFP are typically IA. TABLE 6. MAXIMUM EXTINCTION TIMES AND MINIMUM BURNBACK TIMES FROM PROPOSED ISO SPECIFICATION Extinguishing performance class I II III Burnback resistance level A B C D A B C D B C D Gentle application test Extinction time (min.) not more than Burnback time (min.) not less than not applicable 5 15 5 10 55 not applicable 5 15 5 10 55 5 15 5 10 55 Forceful application test Extinction time (min.) not more than Burnback time (min.) not less than 3 10 3 not tested 3 not tested 3 not tested 4 10 4 not tested 4 not tested 4 not tested not tested not tested not tested not tested not tested not tested PERFORMANCE FIRE TESTS. The previous sections outlined requirements for foams in terms of the recognition of AFFF and FFFP, minimum application rates, and references to performance standards. Reference 24 provides additional details on NFPA requirements. Particularly in the NFPA standards, performance requirements are dictated in terms of "listing" and approval by the "authority having jurisdiction." Currently at U.S. airports, the airport managers are effectively the authority having jurisdiction in terms of foam specification. As shown in the airport survey, the U.S. AFFF Military Specification was the predominant performance specification referenced. Previous NFPA references to "listing" effectively translated to UL listing in accordance with UL 162. when applied to North America. Therefore, these two standards are evaluated here. 20 US00006760 UL STANDARD 163. UL 162, "Standard for Foam Equipment and Liquid Concentrates," is the principle test standard for the listing of foam concentrates and equipment in the United States. Test procedures outlined in this standard have been developed to evaluate specific agent/proportioner/discharge device combinations. When a foam concentrate is submitted for testing, it must be accompanied by the discharge devices and proportioning equipment with which it is to be listed. These devices do not necessarily have to be manufactured by the foam vendor submitting the agent to be tested. Listed products are then described in the UL Fire ProtectionEquipment Directory. Each listing includes the discharge and proportioning devices with which the agent was tested. UL defines foam liquid concentrate as either a protein or synthetic based agent that is intended to be diluted with fresh water, salt water, or a mixture of both fresh and salt water to a concentration of 1 percent or higher. Different types of low-expansion liquid concentrates are defined as follows: 1. AFFF - A liquid concentrate that has a fluorinated surfactant base plus stabilizing additives. 2. Protein - A liquid concentrate that has a hydrolyzed protein base plus stabilizing additives. 3. Fluoroprotein - A liquid concentrate that is similar to protein type concentrate, but with one or more fluorinated surfactant additives. 4. FFFP - A liquid concentrate that has both a hydrolyzed protein and fluorinated surfactant base plus stabilizing additives. 5. Synthetic - A liquid concentrate that has a base other than fluorinated surfactant or hydrolyzed protein. Foam liquid concentrates, as noted, are not listed as agents alone. Listed with a system, they are associated with discharge devices classified as Type I, II, or III. Type I devices deliver foam gently onto the flammable liquid fuel surface, e.g., a foam trough along the inside of a tank wall. Type II discharge devices deliver foam onto the liquid surface in a manner which results in limited submergence of the foam below the fuel surface and restricted agitation at the fuel surface. Examples include subsurface injection systems, tank wall mounted foam chambers, and applications where foam is bounced off the wall of a tank. Type III discharge devices deliver foam directly onto the liquid surface and cause general agitation at the fuel surface, e.g., hand held nozzles. The flammable liquid fire tests in the UL 162 standard include methods for sprinklers, subsurface injection, and topside discharge devices, including nozzles. The Class B fire tests for topside discharge devices are described in section 15 of UL 162. Commercial grade n-heptane is placed in a square test pan. The area of the pan is a minimum of 50 ft2 (4.65 m2). For Type III applications, the test nozzle is positioned above the test pan. The nozzle may be moved throughout the duration of foam application or fixed in position for part or all of the application. The application rates ("densities" in the UL Standard) for various concentrates are outlined in table 7. Film forming fluoroprotein concentrates are required to pass the fire extinguishment and burnback tests at both application rates. 21 US00006761 TABLE 7. FOAM APPLICATION RATES AND TORCH EXPOSURE TIMES IN UL 162 FOR HYDROCARBON FUELS Concentrate Protein, fluoroprotein, film forming fluoroprotein*11*, or synthetic concentrate Aqueous film-forming or film forming fluoroprotein"1* concentrate Application Rate (gpm/ft2 (Lpm/m2)) 0.06 (2.4) 0.04 (1.6) Time of Foam Application (min) 5 3 Maximum Extinguishment Density (gal/ft2 L/m2)) 0.3 (12.2) Duration of Torch Testing (min) 15 0.12 (4.9) 9 (a) Film-forming fluoroprotein is to be tested at application rates of 0.06 and 0.04 gpmyft2. From UL 162, Sixth edition After the fuel has been added to the test pan, the nozzle arranged, and the liquid concentrate flow rate determined, the fuel is ignited. The resulting fire is allowed to burn for a 60-second prebum time. At the end of the 60-second prebum, foam is discharged for the duration specified in table 7. The foam blanket resulting from the foam discharge must spread over and completely cover the fuel surface, and the fire must be completely extinguished before the end of the foam discharge period. After all of the foam is discharged, the foam blanket formed on top of the fuel is left undisturbed for the period specified in table 7. During the time the foam blanket is left undisturbed, a lighted torch is passed approximately 1 inch (25.4 mm) above the entire foam blanket in an attempt to reignite the fuel. The fuel may not reignite, candle, flame, or flashover while the torch is being passed over the fuel. However, candling, flaming, or flashover that self-extinguishes is acceptable provided that the phenomenon does not remain in one area for more than 30 seconds. After the attempts to reignite the fuel with the lighted torch are completed, a 12-in-diameter (305 mm) section of stovepipe is lowered into the foam blanket. The portion of the foam blanket that is enclosed by the stovepipe is removed with as little disturbance as possible to the blanket outside the stovepipe. The cleared fuel area inside the stovepipe is ignited and allowed to burn for 1 minute. The stovepipe then is slowly removed from the pan while the fuel continues to burn. After the stovepipe is removed, the foam blanket must either restrict the spread of fire for 5 minutes to an area not larger than 10 ft2 (0.9 n r), or flow over and reclose the burning area. A standard test nozzle is not specified. Rather, a test nozzle is used which has foam expansion and drainage values equivalent to those produced with the full-scale nozzle submitted as part of the system being evaluated. The full-scale nozzle is then listed with the concentrate. This test method was originally developed for testing protein foams which used air-aspirating devices. Despite the subsequent inclusion of AFFFs, the method is still geared to evaluate air-aspirated devices. This is evidenced in a recent listing of AFFF and FFFP concentrates. Only one combination which uses a nonaspirating nozzle was identified in the UL Directory: Elkhart Brass Model HF-350 and HF-500 nozzles with 3M FC-600 ATC proportioned at 3 percent. No nonaspirating monitors or rooftop CFR turrets of any type are listed with AFFF or FFFP concentrates. 22 US00006762 This is a serious limitation with regard to CFR applications. Nonair-aspirated hand line nozzles, used in conjunction with air-aspirated and nonair-aspirated roof and bumper turrets, are the predominant foam discharge devices used in CFR applications in the United States. This limitation was recognized by UL; they have dropped references to CFR applications in the Scope of the Sixth Edition of the UL 162 Standard, effective March 7, 1989. >6 , t* ,, _ Because UL 162 is not an agent specification, there are no requirements for physical properties, such as film formation and sealability, corrosion resistance, and spreading coefficient. Neither are there any provisions to test, on a large scale, the degree of dry chemical compatibility of an agent, or the effects of aging or mixing with agents of another manufacturer. However, it should be noted that UL is considering such requirements. In particular, requirements for a positive spreading coefficient (greater than zero using cyclohexane) for film-forming foams have been proposed and are being implemented.26 U.S. MILITARY SPECIFICATION. The US Military Specification, MIL-F-24385, is the AFFF procurement specification for the U.S. Military and Federal Government. The US military, in all likelihood, is the largest user of foam in the world. The inherent and primary purpose of the specification is to obtain a product which will rapidly control and extinguish hydrocarbon fuel fires. It is important to recognize that it is a procurement specification as well as a performance specification. As a result, there are also requirements for packaging, initial qualification inspection, and quality conformance inspection. Equipment designs unique to the military, in particular U.S. Navy ships, also impact on the specification requirements (e.g., use of seawater solutions and misproportioning related fire tests). Nevertheless, by its very design it exacts a high level of fire extinguishment performance. It addresses not only fire extinguishment and bumback requirements, but important chemical and physical properties as well. These requirements have been developed based on research and testing at the Naval Research Laboratory and actual operational experience with protein and film forming foams. Table 8 summarizes the important fire extinguishment, burnback resistance, film formation, and foam quality requirements established by the AFFF MIL SPEC. The fire tests are conducted using 28 ft2 (2.6 n r) and 50 ft2 (4.6 m2) circular fire test pans. There are specific requirements to conduct a fire test of the agent after it has been subjected to an accelerated aging process (simulating prolonged storage) and after intentionally misproportioning the concentrate with water. In particular, the requirement to conduct a fire test of the agent at one-half of its design concentration is one of the most difficult tests. The 28 ft2 (2.6 n f) half-strength fire test must be extinguished in 45 seconds, only 15 seconds greater than allowed when the full-strength solution is used. The physical and chemical properties evaluated for MIL SPEC agents are outlined in table 9, along with the rationale for each test. These procedures have been developed based on experience and specific military requirements. Some of these requirements obviously have relevance to CFR applications. For example, the MIL SPEC requires that the agent be compatible with dry chemical agents. Dry chemical agents may be used as "secondary" agents in CFR, e.g., to combat three dimensional fuel fires, where AFFF may have limited effectiveness. Specifically, the MIL SPEC requires that an agent's compatibility with potassium bicarbonate dry chemical agent (PKP) be determined. The burnback time of the toam in the presence of the dry chemical is measured. Also, the concentrate of one manufacturer must be compatible with concentrates of the same type furnished by other manufacturers, as determined by fire tests and accelerated aging tests. 23 US00006763 TABLE 8. SUMMARY OF THE U.S. MILITARY AFFF SPECIFICATION (MIL-F-243 85, REVISION F) KEY PERFORMANCE REQUIREMENTS Test Fuel Fire Extinguishment 28 ft1 (2.6 m2) fire test Application rate Maximum extinguishment time Maximum extinguishment density 50 ft2 (4.6 m:) fire test3 Application rate Minimum 40-second summation Maximum extinguishment time Maximum extinguishment density Fire Extinguishment -- Over and Under Proportioning (28 ft2 (4,6 m2) Test) Half strength Maximum extinguishment time Maximum extinguishment density Quintuple (5x) Strengthb Maximum extinguishment time Maximum extinguishment density Bumback Resistance 28 ft2 (2.6 m:) fire test 50 ft2 (4.6 m2) fire test Foam Quality Expansion ratio 25% drainage time Film Formation Spreading coefficient Fuel Minimum value Ignition resistance test Fuel Pass/fail criteria Revision F 0.071 gpm/ft2 (2.9 Lpm/m2) 30 s 0.036 gal/ft2 (1.45 L/m2) 0.04 gpm/ft2 (1.6 Lpm/m2) 320 s 50 s 0.033 gal/ft2 (1.34 L/m2) 45 s 0.054 gal/ft2 (2.2 L/m2) 55 s 0.066 gal/ft2 (2.7 L/m2) 25% maximum at 360 sb 25% maximum at 360 s 6.0 : 1 minimum 150 s minimum Cyclohexane 3 Cyclohexane No ignition ' Salt water only. h 300 s for half-strength solutions; 200 s for quintuple-strength solutions 24 US00006764 TABLE 9. PHYSICAL/CHEMICAL PROPERTIES AND PROCUREMENT REQUIREMENTS OF THE AFFF MIL SPEC Requirement Rational Refractive Index enable use of refractometer to measure solution concentrations in field; this is most common method recommended in NFPA 412 Viscosity assures accurate proportioning when proportioning pumps are used; e.g., balanced pressure proportioner or positive displacement injection pumps PH assures concentrate will be neither excessively basic or acidic; intention is to prevent corrosion in plumbing systems Corrosivity limits corrosion of and deposit buildup on metallic components (various metals for 28 days) Total Halides/Chlorides limits corrosion of and deposit buildup on metallic components Environmental Impact biodegradability, fish kill, BOD/COD; assures an environmentally safe product Accelerated Aging film formation capabilities, fire performance, foam quality; assures a long shelf life Seawater Compatibility assures satisfactory fire performance when mixed with brackish or salt water Interagent Compatibility allows premixed or storage tanks to be topped off with different manufacturers' agents without affecting fire performance Reduced and Over Concentration Fire Test assures satisfactory fire performance when agents are proportioned inaccurately Compatibility with Dry Chemical (PKP) assures satisfactory fire performance when used in conjunction Agents with supplementary agents Torque to Remove Cap able to remove without wrench Packaging Requirements strength, color, size, stackable, minimum pour and vent opening tamper proof seal; assures uniformity of containers and ease of handling Initial Qualification Inspection establish initial conformance with requirements Quality Conformance Inspection (each lot) assures continued conformance with requirements Also included are requirements related to corrosivity, pH, concentrate viscosity, total halides, and environmental impact (e.g., biodegradability). Detailed packaging requirements are included, again developed based on experience in handling the product. For example, the maximum torque of the container cap is specified so that the cap can be removed by hand. This assures rapid agent transfer for refilling operations in an emergency. In addition to the initial qualification approval and inspection, a 25 US00006765 quality conformance inspection of each lot of agent must be performed. The manufacturer is currently permitted to submit certified data for quality conformance. Having met requirements of the MIL SPEC, agents are listed on the QPL27, published by the U.S. Department of Defense. TEST RESULTS FAA TESTS. LABORATORY AND SMALL-SCALE TESTS. George Geyer of the FAA has performed the most detailed comparative analysis to date on foam agents relative to performance. Preliminary results were presented at the International Conference on Aviation Fire Protection in Interlaken, Switzerland, in September 198728. The summary data were made available for this report; the actual test notes and data were not available for review. Twenty-four agents, including alcohol-type foams, were evaluated. Agents were classified as PF, FPF, FFFP, and AFFF. In addition to fire tests, the chemical composition, spreading coefficients and expansion, and drainage characteristics of foam agents were evaluated. Fire tests, 50 ft2 (4.6 m2) in size, were conducted in accordance with both the AFFF MIL SPEC, Revision C and UL 162. The discharge rate and resulting application rate was modified to produce higher rates for the protein based nonfilm-forming agents. Average results of these tests are summarized in tables 10 to 13. The data indicate that AFFFs, as a group, have better control, extinguishment, and burnback characteristics compared to FFFPs. Fourteen AFFF agents were evaluated. Disregarding the Ansul ARC and the National Aer-O-Water tests having an application rate greater than 0.04 gpm/ft2 (1.6 Lpm/m2), the range of control and extinguishment times are 19-39 seconds and 36-63 seconds respectively for AFFFs. The range of 25 percent burnback times is 345-564 seconds. The data show that there is a range of performance for AFFF concentrates. The control and extinguishment times for the FFFP agents tested were 34-43 seconds and 53-74 seconds respectively. Twenty-five percent burnback ranged from 241-423 seconds. The average control, extinguishment, and burnback times for the QPL AFFF agents were 22, 43, and 436 seconds, respectively, compared to average control, extinguishment, and burnback times of 39, 59, and 356 seconds for the FFFP agents. The differences in foam agent performance are shown graphically in figure 8, which is a comparison of representative agents using the MIL SPEC and UL test methods. The trends in the data remain essentially the same, independent of the test method. AFFFs perform better than FFFPs, which in turn perlorm better than FPs in terms of fire control and extinguishment. The differences in control and extinguishment times between the tests methods may be attributed to differences in the pan configuration and method of foam application. The MIL SPEC uses a round pan around which the firefighter may move, while UL 162 uses a square pan and the fire fighter must remain stationary while applying the agent. It should be noted that the QPL products were not evaluated in this comparison. As part of a related analysis of physical and chemical properties, Geyer attempted to establish correlations between agent spreading coefficient and fire performance. Spreading coefficient values were first determined for six agents, each on three different fuels. The same agents were then subjected to 50 ft" (4.6 n r) MIL SPEC Tire tests using each test fuel. The results showed that no direct correlation existed between spreading coefficient and extinguishment performance of the agents tested. 26 US00006766 TABLE 10. FIRE PERFORMANCE OF AFFF CONCENTRATES ON MIL SPEC 50 ft2 (4.6 m2) FIRE TEST CONDUCTED BY FAA Concentrate 3M Lightwater FC 206 CEa 3M Lightwater FC 203 CEa 3M Lightwater FC 201 3M Lightwater ATC FC 600 Angus Tridol 6 % Angus Tridol 3 % Ansul Ansulite AFC3 6%a Ansul Ansulite AFC3A 3%J Ansul Ansulite 1% Ansul Ansulite ARC National Aer-O-Water 6% National Aer-O-Water 3% National Aer-O-Water 3%a Military 3 % National Aer-O-Water Universal Military QPL product Percent Proportioning 6 3 1 3 6 3 6 3 1 3 6 3 3 3 3 3 Application Rate (gpm/ft2 (Lpm/m2)) 0.04 (1.6) 0.04 0.6) 0.04 (1.6) 0.04 (1.6) 0.04 (1.6) 0.04 (1.6) 0.04 (1.6) 0.04 (L6) 0.04 (1.6) 0.04 (1.6) 0.04 (1.6) 0,04 (1.6) 0.04 (1.6) 0.06 (2.4) 0.10 (4.1) 0.04 (1.6) Control Time (s) 20 25 21 20 25 39 24 23 26 70 22 29 19 20 17 36 Extinguish Time (s) 36 42 43 42 45 63 44 46 43 92 37 55 47 32 27 60 40 s Summation <%) 346 333 348 342 323 275 331 329 318 58 340 286 341 354 365 270 25% Burnback (s) 485 428 503 564 397 345 495 422 463 288 450 365 352 614 637 434 Spreading Coefficient vs. Cyclohexane 3.01 4.74 2.01 2.86/2.86 4.40 5.20 3.40 4.29 4.00 5.24/3.94 2.22 4.57 4.56 5.12/5.07 TABLE 11. FIRE PERFORMANCE OF FILM-FORMING CONCENTRATES CONDUCTED BY FAA Concentrale Angus Petroseal 6 % Angus Petroseal 3% National Aer-O-Film 3% Percent Proportioning 6 3 3 Application Rate (gpm/ft2 (Lpm/m2)) 0.04 (L6) 0.04 (1.6) 0.04 (1.6) Control Time (s) 43 34 40+ Extinguish Time (s) 61 53 74 40 s Summation (%) 228 240 245 25% Burnback (s) 423 404 241 Spreading Coefficient vs. Cyclohexane 4.00 2.60 4.14 TABLE 12. FIRE PERFORMANCE OF FLUOROPROTEIN FOAM CONCENTRATES CONDUCTED BY FAA Concentrate Angus FP 570 6% Angus FP 70 3% Angus Alcoseal 3%/6% National Aer-O-Foam XL6 6% National Aer-O-Foam XL3 3% Percent Proportioning 6 3 3 6 3 Application Rate (gpm/ft2 (Lpm/m2)) 0.06 (2.4) 0.06 (2.4) 0.06 (2.4) 0.06 (2.4) 0.06 (2.4) Control Time (s) 98 112 45 98 85 Extinguish Time (s) 258 240 84 174 161 40 s Summation (%) 100 118 153 138 130 25% Burnback (s) 711 549 341 741 787 TABLE 13. FIRE PERFORMANCE OF PROTEIN FOAM CONCENTRATES CONDUCTED BY FAA Concentrate Angus Nicerol 6% Angus Nicerol 3% Percent Proportioning 6 3 Application Rate (gpm/ft2 (Lpm/m2)) 0.10 (4.1) 0.10 (4.1) Control Time (s) 80 70 Extinguish Time (s) 181 None 40 s Summation (%) 160 145 25% Burnback (s) 225 - US00006768 180 150 0 UL 162 Fire Test Procedure MIL-F-24385C Fire Test Procedure --------Fire Control Fire extinguishment FFFP Fluoroprotein Foam (FP) 120 90 60 30 E h '" 0 -----!------- ---- !----I ------- 1--------- 1 I---------- 1 ---- !--------- --------1------ 3M 1% FC-201 Angus Trldol 3% N atio n al 3% A e ro w ater 3M ATC FC-600 Angus 3% Petroseal N a tio n a l 3% A e r-o -fllm Angus A lco seal N a tio n a l XU Angus FP 570 6% FIGURE 8. SUMMARY OF 50 FT2 (4.6 M2) FIRE TESTS, FROM FAA TESTS 28 This can be seen from tables 10 and 11, where spreading coefficients and extinguishing data are shown for the 50 ft2 (4.6 m2) fire tests. Revision C of the MIL SPEC requires a minimum spreading coefficient of 3 using cyclohexane as the test fuel. There are agents listed in tables 10 and 11 which exceed this criteria (Angus Tridol 3 percent, National Aer-O-Water 3 percent, Angus Petroseal 6 percent), but do not pass the 50 ft2 (4.6 m2) extinguishment criteria of 50 seconds. Likewise, agents with a spreading coefficient less than three were able to meet the extinguishment limit (3M FC 201, 3M ATC FC 600, National Aer-O-Water 6 percent). Additional data on physical/chemical parameters from the FAA tests and the effects of test fuels are contained in appendix A. LARGE-SCALE TESTS. The principle objective of the large fire tests conducted by FAA was to evaluate those agents which demonstrated the most rapid fire control and extinguishing times using the MIL-F-24385C and Underwriters Laboratories, Inc., UL 162 test methods. The results of the 50 ft2 (4.6 m2) fire tests performed in accordance with the MIL SPEC are contained in the previous section. Based upon these data, two 3 percent type film-forming foam agents were selected. One agent was an AFFF manufactured to conform with the military specification (Ansul 3 percent). The second agent was a commercial FFFP agent listed by UL (Petroseal Angus Fire Armour). The fire test bed was a 79 ft (24 m) square (6241 ft2, 516 m2) diked fire area in one comer of which an additional 50 ft (15 m) square (2500 ft2, 232 m2) fire pit had been constructed. The first series of tests was performed in the 2500 ft2 (232 m2) fire pit, after which the dikes were removed before conducting the second series of tests in the 6241 ft2 (576 m2) fire pit. During the tests, all foam solutions were discharged at the rate of 250 gpm (950 Lpm), which provided application rates of 0.04 and 0.10 gpm/ft2 (1.6 and 4.1 Lpm/m2) to the fire surface. These rates were within the known threshold values for aqueous film-forming foams as shown previously in figure 5. Both fire pits were initially charged with sufficient water to provide a smooth water-based substrate upon which Jet A (0.35 gal/ft2, 14.2 L/m2) aviation fuel could be floated. A prebum period of 30 seconds was allowed after complete involvement of the fuel surface was obtained before initiation of the fire extinguishing operation. The nozzle was positioned on the upwind side of the active fire pit and operated by an experienced firefighter committed to extinguishing the fire as rapidly as possible. Two different foam nozzles were employed in the experiments. One nozzle was a single-barrel air aspirating unit (National Foam P/N BC-31B) with a nominal solution discharge rate of 250 gpm (950 Lpm) at 100 psi (690 kPa). The second nozzle was a short-barrel nonair-aspirating unit (Valpariso IN 46383, Task Force Tip). The average foam quality produced by each nozzle using the NFPA 412 foam test method, expansion ratio and 25 percent solution drain time, is shown in table 14. The results of the fire tests are summarized in figure 9. Two large-scale tests were performed at an application rate of 0.04 gpm/ft2 (1.6 Lpm/m2) using the air-aspirating nozzle, and four at the rate of 0.10 gpm/ft2 (4.1 Lpm/m2), employing both the air-aspirating and nonair-aspirating nozzles. 30 US00006770 50 O Film-Forming Fluoroprotein (Air-Aspirated) G Aqueous Fifm-Forming Foam (Air-Aspirated) O Aqueous Film-Forming Foam (Nonair-Aspirated) A Film-Forming Fluoroprotein (Nonair-Aspirated) 40 O 30 20 o 10 o A 0 I I I----------------- 1-----------------1-- -----------1-----------------0.02 0.04 0.06 0.08 0.10 0.12 0. Foam solution application rate (gpm/ft2) FIGURE 9. FIRE CONTROL FOR LARGE-SCALE FIRE TESTS OF FFFP AND AFFF TABLE 14. FOAM QUALITY FOR LARGE-SCALE AFFF/FFFP TESTS Agent AFFF FFFP Type percent 3 3 Average Solution Concentration % 2.8 2.6 Expansion Ratio Airaspirated Nonairaspirated 6.7 : 1 4.9 : 1 5.8 : 1 5.0 : 1 Solution Drain Time 25% (s) Airaspirated Nonair-aspirated 191 86 199 108 The average fire control times obtained for FFFP and AFFF on Jet A fuel fires were essentially equal at a solution application rate of 0.10 gpm/ft2(4.1 Lpm/m:). The difference in control times between the air-aspirating and nonair-aspirating nozzles is not significant. This indicates that the threshold or critical application rate was exceeded by both agents. When the solution application rate was reduced from 0.10 to 0.04 gpm/ft2 (4.1 to 1.6 Lpm/m2), the time for fire control for AFFF was nine seconds less than that lor the FFFP. The control times in the 6240 ft2 (516 nr) tests with the lower application rate were in good agreement with the control times from the 50 ft2 (4.6 m2) MIL SPEC tests (tables 10 and 11). NRL TESTS. Because of the wide variation in the fire test data reported in the literature, a series of comparative fire and bench-scale laboratory tests with FFFP and AFFF concentrates were performed by the Naval Research Laboratory24. Bench-scale tests were performed according to the MIL SPEC (Revision C) test procedures, including spreading coefficient, film formation and sealability characteristics, fluorine content, expansion ratio, and 25 percent drainage time. The spreading coefficient test was described earlier. The film formation and sealability test is a fundamental bench-scale test which confirms that the agent is in fact able to produce a film on the fuel surface. It also indicates whether or not the film will seal vapors against ignition. Fluorine content is used to judge the amount of fluorinated surfactant present in the agent. Expansion ratio and 25 percent drainage time are physical measurements which determine the quality of the foam produced. Fire tests were conducted using the 28 ft2 (2.6 m2) and 50 ft2 (4.6 m2) MIL SPEC test methods. Motor gasoline was used in both tests; n-heptane was also used in the 50 ft2 (4.6 m2) test. To make a preliminary assessment of the FFFP with a nonair-aspirated discharge device, an ad hoc test was performed comparing nonair-aspirated agents. A manufacturer of FFFP products supplied a sample for testing. The two AFFF products used were both 6 percent agents qualified under Revision C of the AFFF MIL SPEC. They were obtained from the Navy supply system. Test methods followed the MIL SPEC Revision C criteria, except where n-heptane was substituted as a test fuel. Complete results are detailed in reference 24 and summarized in appendix B. The AFFF had higher surface tensions and lower interfacial tensions compared to the FFFP. The FFFP had a negative spreading coefficient when tested with n-heptane. No across-the-board correlations between spreading coefficients and fire control, extinguishment, and burnback resistance were apparent. 32 US00006772 Likewise, there were no direct correlations between fluorine content and fire performance. Average fire control, extinguishment, and burnback times were better for the MIL SPEC AFFF agents compared to the FFFP in all test situations, with greater differences observed when n-heptane was used as the test fuel in the 50 ft.2 (4.6 m2) test. The overall results were in agreement with the results from the FAA tests. The MIL SPEC AFFF had better fire extinguishment and burnback performance compared to FFFP. No direct correlations between fire extinguishment and burnback performance and the small-scale spreading coefficient, film and seal, and expansion and drainage tests were observed. Yet, the film-forming agents formulated to the MIL SPEC consistently yielded better fire control and burnback performance. OTHER FIRE TESTS. In order to assess the performance differences of FFFP compared to AFFF, a review of existing test data was performed24. Because FFFP is a relatively new product, there was limited small- and large-scale test data available compared to the considerable amount of data available for protein, fluoroprotein, and AFFF products. A detailed description of the literature and test data review is presented in reference 24. It is extremely difficult to analyze the results from the literature on a one-to-one basis. Aside from the problems in relating different fire test methods, a more fundamental problem occurs in distinguishing individual foam concentrates. For example, it is widely accepted that AFFF concentrates which are formulated by a given manufacturer to meet the MIL SPEC may be a different formula than that submitted by the same manufacturer for UL listing. Furthermore, a manufacturer may have different formulas for the international market than for the U.S. domestic or military markets. The so-called "quality" of an agent may also be a function of the manufacturers' primary market. A vendor whose primary market is AFFF may devote more resources for different AFFF "blends" to serve different markets. Alternately, a vendor whose market is derived primarily from fluoroprotein concentrates may market AFFF only as needed, e.g., to provide "complete" service. Rarely are these differences distinguished in the literature and available test reports. It is uncommon to find the lot number and date of manufacture of foam concentrate reported in test data found in the literature. These factors explain, in part, the findings of the literature review. In some cases, the AFFFs are shown to be generally better than FFFPs . In other cases, FFFPs are shown to be equal to or even better than AFFF. The data reviewed in reference 24 clearly show that all AFFFs are "not created equal", i.e., do not have the same control and fire extinguishing performance. Likewise, the data also show that all FFFPs are not equal in performance. An example of the difficulty in assessing data where MIL SPEC or QPL agent is not specified is evident in the literature published by the Scientific Research and Development Branch (SRDB) of the Home Office of the United Kingdom. They have performed one of the few referencable test series on FFFP2y. The objective was to assess suitable foams for hose reel systems for control and extinguishment of Class B fires. The agents tested included fluoroprotein, AFFF, and FFFP agents. Alcohol-type FFFP and AFFF agents were also tested. Gasoline (petrol) fires in a 431 ft2 (40 m2) circular fire test area were extinguished with the hose reel system flowing 26.5 gpm (100 Lpm). The effective application rate was 0.061 gpm/ft2 (2.5 Lpm/m2). Tests were conducted using aspirated and nonaspirated hose reel nozzles. After fire extinguishment, burnback tests were performed. The test report provides details on the test setup, procedure, and equipment. Data from the large-scale tests are summarized in table 15. The data 33 US00006773 show that the AFFF and FFFP agents tested had essentially equivalent fire control and extinguishment performance. When used with the aspirating nozzle, the FFFP had a greater average burnback time. The author concludes that all agents tested gave poor performance, both for extinguishment and burnback resistance, when applied through the nonaspirating device. In two regards, these tests contradict the massive amount of data in the tests conducted with AFFF: the extinguishment density required to extinguish hydrocarbon pool fires and the use of nonair-aspirated AFFF for handline operations. The control extinguishment densities in table 14 are three times the densities achieved for control large-scale test fires reported by FAA (figure 9) and two to three times the application densities reported in the literature review in the Historical Basis section (appendix C). The issue of air aspiration and the apparent advantages on nonair-aspirated AFFF were also described earlier. The authors conclude that, at least for the aspiration issue (which also contradicted earlier SRDB tests), very low nozzle aspiration (e.g., less than NFPA 412 recommendations) may be the problem. The issue of the high extinguishing densities remains unanswered. It may be an agent, fuel, or discharge device issue. More recently, the Fire Research and Development Group (FRDG) in the United Kingdom performed comparative foam tests30. The data are summarized in table 16. A 602-ft2 (56 m2)-circular fire using lead-free petrol was extinguished using an air-aspirating nozzle discharging at 60 gpm (225 Lpm). The application rate was 0.1 gpm/ft2 (4 Lpm/m2). Commercial foams readily available in the United Kingdom were used, but there was no indication whether the concentrates met any specific performance test criteria (e.g., a UL-type test). Foams were also tested at reduced strength. The average 90 percent control times (51 s) of the two AFFF products were slightly better than the control times for the FFFP concentrates (58 and 63 s). In particular, one AFFF product performed very poorly when reduced to half strength. The author has previously expressed concern that the proposed ISO/CEN specification would not distinguish performance differences at reduced concentrations.31 The author notes that the results show that large variations in performance can be expected from different products of the same foam type. CORRELATION BETWEEN SMALL- AND LARGE-SCALE FIRE TEST RESULTS SMALL-SCALE TEST PARAMETERS AND VARIABLES. The previous sections described the variation in test methods, the results of common small-scale tests, and the development of aviation foam criteria based on large-scale results. Table 17 outlines the variables associated with foam performance and testing. As shown, there are an incredible number of variables associated with foam performance. These include factors involving foam bubble stability and fluidity, actual fire test parameters (fuel, nozzle, application rate), and environmental effects. Even the fundamental methods of measuring foam performance (knockdown, control, and extinguishment) vary. For example, Johnson31 reported that FFFP fails the proposed ISO gentle application tests because small flames persist along a small area of the tray rim. He states that, to get around this inconvenience, the foam committees have redefined extinction to include flames. Given all of these variations, it is no wonder that tests and specifications for various foams and international standards have different requirements. This is reflected in table 18, which compares four key parameters of the MIL SPEC, UL, ICAO, and ISO standards. There is no uniform agreement between test fuel, application rate, the allowance to move the nozzle, and the extinguishment application density for AFFF. There is a factor 34 US00006774 TABLE 15. SUMMARY OF HOSE REEL FIRE TEST DATA FROM SRDB29 Foam Type AFFF Application Aspirated AFFF Nonaspirated (Spray) AFFF-AR Aspirated AFFF AR FFFP Nonaspirated (Spray) Aspirated FFFP FFFP AR Nonaspirated (Spray) Aspirated FFFP-AR FP Halofoam Nonaspirated (Spray) Aspirated (FRS Branchpipes) Nonaspirated (Spray) Test No. 3 5 9 Average 6 7 8 Average 15 16 18 Average 19 4 10 11 Average 12 13 14 20 Average 21 29 90% Extinguishment Times (min : s) 1 ; 08 1 : 06 1 : 24 I : 13 2 : 42 4 : 35 3 : 25 3 : 34 1 : 54 0 : 57 1 : 14 1 : 22 4 : 26 1 : 07 1 : 17 1 : 23 1 : 16 3 : 54 3 : 40 1 : 56 2 : 02 2 : 33 3 : 19 1 : 39 100% Extinguishment Times (min : s) 1 : 45 1 : 50 2 : 26 2 : 00 4 : 39 5 : 30 4 : 22 4 : 50 2 : 31 1 : 25 2 : 21 2 : 06 5 : 27 2 : 18 2 : 07 2 : 01 2 : 09 4 : 26 3 : 57 3 : 50 3 : 32 3 : 46 4 : 54 3 : 15 Volume of Solution Used (gal (L)) 200 (760) 450 (1700) 206 (780) 527 (2000) 209 (790) 426 (1600) 346 (1310) 454 (1720) 315 (1200) Extinguishing Density (gal/ft; (D m 2)) 0.12 (5) 0.28 (11) 0.13 (5) 0.32 (13) 0.13 (5) 0.26 (11) 0.21 (9) 0.28 (11) 0.19 (8) Burnback Time (min : s) 8 : 43 7 : 20 5 : 42 7 : 15 2 : 00 1 : 11 2 : 17 1 : 49 8 : 32 6 : 48 7 : 58 7 : 46 1 : 34 13 : 40 10 : 57 6 : 46 10 : 28 1 : 56 5 : 18 10 : 22 9 : 58 8 : 33 4 : 07 12 : 53 22 23 Average 3 : 46 2 : 49 3 : 18 5 : 52 5 ; 14 5 : 33 533 (2020) 0.37 (13) 4 : 40 6 : 13 5 : 27 US00006775 TABLE 16. SUMMARY OF FIRE TEST DATA FROM FRDGJ|< Foam Type and Normal Cone. Test LJse Cone. Used 1 AFFF(l) 3% 3% 2 AFFF(!) 3% 3% 3 AFFF(l) 3% 2% 4 AFFF(2) 3% 37c 5 AFFF(2) 37c 27c 6 AFFF( 1)3% 1.57c 7 AFFF(2) 3% 1.57c 8 FFFP(l) 3% 3% 9 FFFP(l) 3% 27c 10 FFFP(2) 3% 37c 11 FFFP(2) 3% 27c 22 FFFP(l) 3% 37c 23 FFFP(2) 3% 37c 32 FFFP(l) 3% 1.57c 33 FFFP(2) 3% 1.57c 37 AFFF(2) 3% 37c 38 AFFF(l) 3% 3 7c 43 AFFF(l) 3% 3 7c 90 7c 0 : 54 0 : 59 0 : 52 0 : 55 1 : 25 1 : 24 4 : 23 0 : 59 1 : 26 1 . 12 1 : 30 0 : 57 0: 53 1 : 02 1 : 45 0 : 46 0 : 45 0 : 44 95 7c 1 : 03 1 : 01 0 : 57 1 : 19 1 : 30 1 : 29 4 : 28 1 : 34 1 : 32 1 : 20 1 : 55 1 : 01 0 : 57 1 : 19 1 : 48 0 : 49 0 : 49 0 : 53 Extinction Times (min : s) Virtual Ext. 100 7c Foam App. Period 1 : 10 1 : 29 1 : 26 2 : 24 2 : 53 2 : 29 5 : 14 2 : 05 1 : 58 2 ; 08 2 : 17 4 : 33 1 : 37 1 : 46 2 : 02 1 : 36 1 : 29 1 : 39 2 : 12 4 : 16 1:31 7 : 21 7 : 30 4 : 02 5 : 49 6 : 29 8 : 48 7 : 22 6 : 17 4 : 33 4 : 21 2 : 23 3 : 39 2 : 52 3 : 55 3 : 07 2 : 43 4 : 48 2 : 02 7 : 53 8 : (X) 4 : 33 6 : 19 6 : 35 9 : 18 7 ; 58 6 : 47 5 : 03 4 : 51 2 : 53 4 : 10 3 : 22 4 : 25 3 : 37 Burnback Times (min : s) 25 % 50 % 75 % 100 7c 2 : 50 2 : 56 3 : 03 3 : 18 4 : 57 5 : 05 5 : 13 5 : 34 1 : 38 1 : 54 2 : 07 2 : 31 3 : 36 3 : 44 3 : 54 4 : 03 5 : 33 5 : 55 6 : 18 6 : 39 2 : 26 3 : 09 3 : 27 3 : 27 3 : 21 3 : 36 3 : 45 4 : 09 5 : 09 5 : 18 5 : 28 5 : 49 4 : 49 5 : 06 5 : 37 6 : 07 5 : 55 6 : 18 6 : 27 6 : 39 4 : 39 5 : 29 6 : 12 6 : 23 4 : 45 5 : 05 5 : 17 5 : 44 6 :02 6 : 13 6 : 24 6 : 31 3 : 12 3 : 16 3 : 30 3 : 37 4 : 15 4 : 34 4 : 52 5 : 07 4 : 00 4 : 06 4 : 14 4 : 36 6 : 15 6 : 25 6 : 51 7 : 04 5 : 44 6 : 00 6 : 08 6 : 13 of six differences between the lowest permitted extinguishment application density (MIL SPEC) and the highest (ISO). This significant difference is attributed, at least in part, to the fixed nozzle requirement in the ISO specification. TABLE 17. VARIABLES ASSOCIATED WITH FOAM PERFORMANCE AND TESTING I. Physical/chemical properties of foam solution A. Bubble stability 1. Measures a. Expansion ratio b. Drainage rate 2. Variables a. Water temperature b. Water hardness/salinity c. Water contamination B. Fluidity of foam 1. Measures a. Viscosity b. Spreading rate c. Film formation 2, Variables a. Fuel type and temperature b. Foam bubble stability C. Compatibility with auxiliary agents 1. Measures--fire and bumbacktest 2. Variables a. Other foam agents b. Dry chemical agents D. Effects of Aging 1. Measures fire and bumback test 2. Variable --shelf life of agent 37 US00006777 TABLE 17. VARIABLES ASSOCIATED WITH FOAM PERFORMANCE AND TESTING (continued) II. Test methods to characterize foam performance A. Fuel 1. Measures a. Vapor pressure b. Flash point c. Surface tension d. Temperature 2. Variables a. Volatility b. Depth and size c. Initial temperature of air and fuel temperature d. Time fuel has been burning (e.g., short versus long, and depth of hot layer) B. Foam application method 1. Measures a. Stream reach b. Aspiration of foam c. Foam stability, e.g., contamination by fuel d. Water content of foam e. Proportioning rate 2. Variables a. Aspiration (1) Effect on stream reach (2) Degree to which foam is aspirated and the need to aspirate based on foam type b. Fixed versus mobile device c. Application technique (1) Indirect, e.g., against backboard or sidewall (2) Direct 38 US00006778 TABLE 17. VARIABLES ASSOCIATED WITH FOAM PERFORMANCE AND TESTING (continued) II. Test methods to characterize foam performance (continued) (a) Gentle (b) Forceful (c) Subsurface injection d. Application location (1) High --need to penetrate plume (2) Low e. Application rate of foam f. Wind (as it affects stream reach) (1) Crosswind (2) With and against g. Effect of reduced or increased concentration due to improper proportioning C. Fire configuration 1. Measures a. Fuel burning rate, radiation feedback to fire b. Propensity for reignition c. Surface tension 2. Variables a. Pan/containment geometry b. Two-dimensional (pool) versus three-dimensional (running fuel/atomized spray) c. Presence and temperature of freeboard d. Wind (as it affects flame tilt and reradiation) e. Surface on which there is fuel (1) Rough (2) Smooth (3) Water substrate "peeling" effect of fuel 39 US00006779 TABLE 17. VARIABLES ASSOCIATED WITH FOAM PERFORMANCE AND TESTING (continued) II- Test methods to characterize foam performance (continued) D. Measurement of Results 1. Measures a. Time to knockdown, control, extinguish, and burnhack (1) Actual or estimated time by visual observations (2) Summation values, i.e., summation of control at 10, 20, 30, and 40 seconds b. Heat flux during extinguishment and bumback 2. Variables qualitative and quantitative methods to determine fire knockdown, extinguishment, and bumback a. 90 percent control --measure of ability of foam to quickly control the fire b. 99 percent (virtual extinguishment) -- all but the last flame or edge extinguished c. Extinguishment -- 100 percent d. Bumback --25 percent, 50 percent TABLE 18. EXAMPLES OF EXTINGUISHMENT APPLICATION DENSITIES OF VARIOUS TEST STANDARDS Test Standard MIL SPEC UL 162 ICAO ISO Forceful Fuel motor gasoline heptane kerosene heptane Application Rate (gpm/ft2 (Lpm/m2)) 0.04 (1.6) Nozzle Movement Permitted yes Extinguishment Application Density (gal/ft2 (L/m2)) 0.033 (1.34) 0.04 (1,6) 0.06 (2.5) 0.06 (2.5) yes yes (horizontal plane) no 0.12 (4.9) 0.061 (2.5) 0.19 (7.6) 40 US00006780 No study has been performed to correlate these test methods; given the significant differences in performance characteristics and requirements, it is unlikely that correlation between these test methods could be established, even when considering AFFF only. An AFFF that meets the ICAO standard could not be said to meet the MIL SPEC without actual test data. The problem of correlating differences in small-scale tests was demonstrated by UL32 in a comparison of UL, MIL SPEC, OF555 (U.S. Government protein spec) and United Kingdom test methods. In those tests, differences between different classes of agents (protein vs. AFFF) and between agents within a class (e.g., AFFF) were demonstrated. The results of the recent FRDG tests which indicate that all AFFF agents do not have similar performance characteristics confirm the previous UL findings. The problem of correlation is compounded when a single test method is used in an attempt to assess different classes of foam, e.g., protein and AFFF. Attempts to use a single test method are problematic because of the inherent difference between these foams: protein foams require air aspiration so that the foam floats on the fuel surface. This stiff, "drier" foam is viscous and does not inherently spread well without outside forces (e.g., nozzle stream force). AFFF, because of its film formation characteristics, does not require the degree of aspiration that protein foams require. This heavier, "wetter" foam is inherently less viscous, which contributes to improved spreading and fluidity on fuel surfaces. This is related, at least in part, to the degree of aspiration of the foam. A more exact description of foam aspiration is appropriate. Thomas33 has described three levels of foam aspiration: primary aspirated, secondary aspirated, and unaspirated. Primary aspirated foam occurs when a foam solution is applied by means of a special nozzle designed to mix air with the solution within the nozzle. The consequence is foam bubbles of general uniformity. "Air-aspirated" foam refers to this primary aspirated foam. Secondary aspirated foam results when a foam solution is applied using a nozzle which does not mix air with the solution within the nozzle. Air is, however, drawn into the solution inflight or at impact at the fire. Secondary aspirated foam refers to "nonair-aspirated" foam described in this report. Unaspirated foam occurs when a foam solution does not intake air to form foam bubbles at any stage. From a practical standpoint, unaspirated foam, even AFFF, is not effective on hydrocarbon fuel fires. The correlation between foam solution viscosity and extinguishment time has been shown by Fiala18, but the entire foam spreading and extinguishment theory has yet to be demonstrated based on first principles. Thus, the test standards adopt bench-scale tests which measure a factor of foam fluidity (e.g., spreading coefficient), but fail to recognize the total foam spreading system, including viscous effects. Fundamental understanding of foam mechanisms would promote the development of small/moderatescale test apparatus which potentially have greater direct correlation for predicting large-scale results. The NFPA committee charged with developing foam test criteria for the 1993 Edition of the NFPA 403 standard had to address both of these issues: the correlation between small-scale national and international standards with large-scale results, and the use of a single test method for all foams. The Aviation Committee had, for some time, recognized the need to provide guidelines or standards for foam agents. It had wrestled with the chemical and physical property differences between protein, fiuoroprotein, and aqueous film-forming foams. The Aviation Committee established an Ad-hoc Task Group for Foam Test Performance Criteria. Initial suggestions by the members of the task group varied widely on the direction to pursue. Some recommended adoption or adoption in part of the MIL SPEC, UL 162, or ICAO methods while others suggested a single standard fire test with different application rates. The task group was directed by the Aviation Committee to examine ICAO test methods and philosophies. In particular, they were to examine the concept of using one fire test pan for all tests (i.e., all agents) and using different nozzles/flow rates for each required application density. 41 US00006781 Preliminary tests using this approach were conducted under the direction of Underwriters Laboratories, Inc. Tests were conducted using the 50 ft2 (4.6 nr) ISO foam fire test pan. AFFF, FPF, and FP foams were tested using a 30-second, fixed nozzle application. At the end of 30 seconds, manual firefighting was permitted. The standard ISO DP 7203 burnback method was used. Initial testing with a 2 gpm (7.5 Lpm) application rate for AFFF and 3 gpm (11.4 Lpm) rate for PF and FPF were not sufficient to extinguish fires in 30 seconds. A 3 gpm (11.4 Lpm) rate for AFFF (0.06 gpm/ft2) did not extinguish the fire within 60 seconds. Technique was found to be an issue with these tests. The NFPA Committee concluded the following: 1. Any standard or specification must address protein and fluoroprotein foams as well as film forming foams. In particular, Europe and the United Kingdom use the protein-based foams for CFR. It is inappropriate to delete protein-based foams from the NFPA aviation standard even though the film-forming agents appear to offer more effective protection in terms of application rate requirements. 2. Likewise, it is not appropriate to reduce overall performance, particularly as it relates to AFFF, in an effort to reconcile all existing or potential international situations. For example, the ICAO extinguishment application density of 0.061 gal/ft2is 100 percent greater than that required in the MIL SPEC. 3. The development of a new test method is a lengthy, involved process which requires significant time and effort. In the near term, the development of a single test method which can be used to evaluate all foams is not particularly encouraging. It is improbable that a new method offers a near-term solution. 4. A codified method to judge foam performance is best accomplished by referencing existing test methods at this time. 5. The MIL SPEC for AFFF and UL 162 (Type 3 application) for protein and fluoroprotein foams provide near-term methods for establishing guidance/standards. In a compromise, the Aviation Committee adopted the 50 ft2 (4.6 m2) MIL SPEC fire test method for AFFF and UL 162 method for protein and fluoroprotein foams. Any foam which is used at the lowest design application rate (0.13 gpm/ft2(5.5 Lpm/m2)) must pass the MIL SPEC fire test. It was recognized that countries outside North America might want to adopt other standards, e.g., ICAO. The NFPA committee noted that it was incumbent on the authority having jurisdiction to assure that adopted methods are consistent with the minimum agent rate/quantities they have adopted. Given the significant variables in test methods, one might conclude that the small-scale tests bear no relation to actual CFR situations. The next section demonstrates the correlation between the MIL SPEC fire test methods and large-scale CFR firefighting evolutions. CORRELATION BETWEEN MIL SPEC FIRE TESTS AND LARGE-SCALE FIRES. A comprehensive review of large-scale fire tests was performed as documented in Historical Basis and Test Results sections. In most of the tests cited, the AFFF used was on the MIL SPEC Qualified Products List or had been submitted for evaluation under the MIL SPEC. A key variable in the 42 US00006782 correlation was controlled: the AFFF agent, unless specifically noted, met the criteria of the MIL SPEC. Some protein foam data are also included. Appendix C contains the complete set of fire test data. Variables in the assessment included the following: 1. The application rate --0.03 - 0.36 gpm/ft2 (1.2 - 14.8 L/m2) 2. Test area - 28 ft2 (2.6 m2) to 16,000 ft2 (1500 m2) 3. Fuel low and high flashpoint 4. Foam aeration --air-aspirating nozzle or nonair-aspirating nozzle Ninety percent fire control times were used as the most accurate measure of the fire knockdown performances, which were reported in all tests. This recognizes the inherent ARFF philosophy that rapid knockdown of hydrocarbon fuel fires is required in aircraft incidents. The use of 90 percent control times also eliminates the variability of total extinguishment, which might be dependent on test bed edge effects or running fuel fire scenarios. The effects of aspiration and fuels were investigated. While there are data which show that nonairaspirated AFFF can be used to achieve more rapid control times (see Historical Basis section), there was no clear overall trend in the data in table C-l. For purposes of analysis, data for tests using aspirated or nonair-aspirated nozzles were combined. The effects of fuel differences are shown in figures 2 and 3. For purposes of this analysis, the low flashpoint fuels (less than 0C), including gasoline, heptane, JP-4, Avgas, were used. Insufficient data were available to correlate small- and large-scale data with the higher flashpoint fuels. The tests compared used the manual application technique (''forceful" in ISO terms) where nozzle movement was permitted. Application rate clearly has an effect on control and extinguishment times as demonstrated previously in figures 1 through 5. This was reconfirmed for the data as shown in figure 10, which includes data from all sizes of test fires. Control time increases exponentially as application rate decreases, particularly below 0.10 gpm/ft2 (4.1 Lpm/m2). Variability of the data is shown by the first standard deviation. This curve is somewhat flatter than the asymptomatic curves shown in the earlier work. The scaling of small fires with large fires is shown in figures 11 and 12, which relate the time needed to control the burning fuel surface as a function of fire size. The time needed to control a unit of burning area (s/ft2 or s/m2), designated as the specific control time, is plotted as a function of fire size on logarithmical scales. For low (0.03 - 0.06 gpm/ft2 (1.2 - 2.4 Lpm/m2)) and intermediate (0.07 - 0.10 gpm/ft2 (2.8 - 4.1 Lpm/m2)) application rates, the specific control times decrease linearly as a function of fire area when plotted on log-log scales. Insufficient data were available to establish this correlation for higher application rates. These data are in agreement with data from Fiaia18, which also indicate decreasing specific extinguishment times as a function of burning area for increasing application rates of AFFF. Also, Fiaia shows that, for a constant application rate, AFFFs have lower specific extinguishment times as a function of burning area than those of protein and fluoroprotein foams. Obviously, this linear relationship must change at very large areas; otherwise, the specific control/extinguishment time would go to zero. This is evidenced in figure 11, where the curve flattens at the high area end of the plot. 43 US00006783 0.000 0.001 Application Rate (lpm /m2) 0.002 0.003 0.004 0.005 Application Rate (gpm/ft2) FIGURE 10. AFFF CONTROL TIME AS A FUNCTION OF APPLICATION RATE Specific Control Tim e (sec/ft2) Specific Control Tim e (sec/m 2) Fire Area (m2) 1 10 100 1000 10.0 1.0 : 0.1 10 100 1000 10000 Fire Area (ft2) CCO o o o FIGURE 11. SPECIFIC CONTROL TIMES FOR AFFF AT LOW APPLICATION RATES oO-N)| 00 CJl S pecific Control Tim e (sec/ft2) S pecific Control Tim e (sec/m 2) Fire Area (m 2) 10 100 1000 10.0 1.0 0.1 CCO FIGURE 12. SPECIFIC CONTROL TIMES FOR AFF AT INTERMEDIATE APPLICATION RATES o o o oO-v)j 0O0) Figures 11 and 12 show that higher specific control times are required for the specification test fires (28 and 50 ft2) compared to large fires. This is readily apparent as actual control times for the small fires are on the same order as results from large fires (table C -l). Figure 11 also shows specific control time criteria which was originally proposed for the MIL SPEC12. This original draft proposal included a requirement for 85 percent control in 30 seconds for a 400 ft2 (37 m2) and a 1200 ft2 (110 m2) fire. These requirements were considered redundant based on the small- and larger-scale developmental test data. They were deleted from the MIL SPEC requirements. The FAA criteria for Index A-3 (NFPA 403 Category 1-10) airports is also shown in figures 11 and 12. Using the practical critical control area for these airports and the requirement for fire control in 60 seconds, specific control time as a function of area is shown. The data indicate that specific control times with MIL SPEC products applied at less than design application rates (i.e., 0.13 gpm/ft2) can meet control times established by NFPA and FAA requirements. The limited data for AFFF and FFFP agents which do not meet MIL SPEC requirements suggest that these agents may not meet minimum NFPA and FAA required control times when applied at less than design rates. From these data, it can be concluded that a scaling relationship exists between MIL SPEC small-scale lire tests and actual large-scale CFR scenarios. The MIL SPEC tests are more challenging than the larger tests in terms o f time to achieve control, but this challenging test produces an agent that can meet NFPA and FAA requirements at less than the design application rate. The trend of the data suggests that non-MIL SPEC agent may not provide this same margin of safety. ADDITIONAL PARAMETERS FOR FOAM SPECIFICATIONS Fire control, extinguishment, and burnback performance are obviously the most important aspects of foam quality. There are other important aspects related to fire performance and overall foam quality. From a fire performance standpoint, AFFF of one particular vendor should be compatible with that of another. Both the NFPA and FAA caution against combining agents from different manufacturers without explicit guidance from the suppliers that this is acceptable. In practical terms, this restricts CFR users when they purchase new stocks of concentrate. Agents should also demonstrate compatibility with secondary extinguishing agents, e.g., PKP. It is desirable that a foam specification address these compatibility issues. Researchers in the United Kingdom have identified a potential problem o f agents proportioned at less than design concentration, e.g., 3 percent concentration proportioned at 1 or 2 percent (table 16). In this case, agents proportioned at less than the design concentration reportedly performed satisfactorily on small-scale tests, but at least one AFFF performed poorly in large-scale tests. Other performance criteria are desirable from a quality control standpoint. These include proportioning, storage, and discharge characteristics (e.g., concentrate viscosity, pH, corrosivity), shelf life, and stability. As described in table 9, the MIL SPEC includes criteria to address these foam parameters. In particular, there are compatibility and reduced concentrate strength tests to assure adequate performance under these conditions. For example, the fire performance of a MIL SPEC AFFF proportioned at half its design concentration is only permitted a 15-second increase in extinguishment time using the 28 ft2 (2.6 m2) test method. With this inherent safety factor designed into the agent, there is assurance that a misproportioned AFFF can still be used to combat a hydrocarbon pool fire. Interagent and PKP 47 US00006787 compatibility tests provide assurance that agents, if mixed or used with PKP, will not degrade in performance. Chemical and physical characteristics tests are required in the MIL SPEC to assure overall quality control. Taken overall, the requirements of the MIL SPEC have resulted in the procurement of agents with superior fire performance, proportioning, storage, and shelf life characteristics. These requirements have been developed and refined over more than 25 years o f field use in military aviation and shipboard use. An issue for FAA certification is the need to enforce or enact the entire MIL SPEC or specific criteria related to fire performance, burnback performance, film formation and sealability, and PKP compatibility. In particular, salt water and packaging requirements may not be critical to assure adequate foam performance at FAA certified airports. Some of the packaging requirements involve military logistical requirements and have no obvious civilian application other than providing adequate container integrity and identifying MIL SPEC agents by packaging color code. Salt water test requirements may be applicable if there are situations where brackish water might be used for proportioning foam. An issue is whether foam concentrates would be reformulated by suppliers if selected performance criteria are specified, e.g., 50 ft2 fire and burnback test, PKP compatibility, and film formation only required. Informal discussions with vendors indicate that current MIL SPEC agents may indeed be reformulated if performance requirements are relaxed. For example, formulations which require less fluorosurfactants may be developed if the half strength test is deleted. Cost savings from reduced fluorosurfactant content provide vendors with the impetus to develop such a product. The correlations developed over years of experience (e.g., appendix C) may not apply to these formulations. The scaling relationships (figures 10 and 11), factor of safety, and overall confidence in the agent would have to be reestablished. This would have to be accomplished through a large-scale research project. Given the implications of reestablishing the baseline performance, it appears reasonable to maintain the MIL SPEC in its entirety if it is adopted for FAA certification purposes. CONCLUSIONS 1. FAA primary foam agent requirements are based on rapid control and extinguishment o f a hydrocarbon fuel fire. 2. Large-scale testing was performed to establish minimum AFFF application rates and quantities. These rates and quantities, the lowest permitted for all foam agents, were based on tests with AFFF agents from the MIL SPEC QPL, or agents in substantial conformance with QPL products. 3. There are a wide range of methods and requirements between standard test methods. Differences are substantial even when comparing fundamental measures of foam performance, e.g., extinguishment application density. The MIL SPEC has the most stringent requirements of the standards and specifications reviewed. 4. Fire control results from small-scale MIL SPEC AFFF tests correlate with large-scale test data. 5. Based on the small- to large-scale correlation, agents which meet the MIL SPEC can meet FAA and NFPA criteria at application rates less than the design application rates of 0.13 gpm/ft2 (5.5 Lpm/m2). This provides a factor of safety for products used at the lowest foam agent application 48 US00006788 rate. The limited data available suggest agents that fail to meet the MIL SPEC criteria may not provide this same factor of safety. 6. Given the critical times involved in survivable postcrash fires and the probability that quantities of agent required to extinguish actual aircraft fires may be greater than those for test fires, the factor of safety inherent in MIL SPEC agents is entirely appropriate for FAA certification purposes. The safety factor is needed to address factors such as the level of training of firefighting personnel, inaccessibility of shielded fires, initial overuse of foam, three-dimensional fire scenarios, and difficulties in deployment and control. 7. While MIL SPEC AFFF has been shown to be a superior firefighting agent, no correlation has been established between small-scale physical/chemical properties tests and actual fire and burnback performance. 8. Many of the performance criteria in the MIL SPEC are relevant to civilian aviation situations, e.g., interagent compatibility, PKP compatibility, and performance of misproportioned and old agents. 9. Modifications in the adoption of MIL SPEC criteria may result in formulations which impact overall foam quality. This may require reestablishment of the correlation demonstrated between the small- and large-scale test results. 10. The proliferation of standard test methods and criteria has not yielded significant benefits in our understanding of fundamental foam extinguishing mechanisms. Future work should focus on the use of first principles to establish fundamental foam extinguishment mechanisms. RECOMMENDATIONS 1. The FAA should adopt the MIL SPEC in its entirety as criteria for accepting foam agents used at the 0.13 gpm/ft2 (5.5 Lpm/m2) application rate ("AFFF" flow rate category). 2. Conformance with the UL 162 standard is acceptable for agents used at the higher 0.20 gpm/ft2 (8.2 Lpm/m2) application rate. 3. The FAA should support research and development of bench-scale test methods based on first principles, which can be used to predict large-scale performance. Optimally, these methods could be used to predict performance of any foam agent on a hydrocarbon fuel spill fire. They could also be used to evaluate alternative foam agent formulations at a bench scale. 49 US00006789 REFERENCES 1. Federal Aviation Administration, "Aircraft Fire and Rescue Facilities and Extinguishing Agents," Advisory Circular No. 150/5210-65, Washington, DC, January 28, 1985. 2. Geyer, G., "Equivalency Evaluation of Firefighting Agents and Minimum Requirements at U.S. Air Force Airfields," FAA Technical Report DOT/FAA/CT-82/109, Atlantic City, NJ, October 1982. 3. National Fire Protection Association, "NFPA 403, Standard for Aircraft Rescue and Firefighting Services at Airports," Quincy, MA, 1993 Edition. 4. Underwriters Laboratories, Inc., "UL 162, Standard for Foam Equipment and Liquid Concentrates," Northbrook, IL, Sixth Edition, March 7, 1989. 5. Lindemann, T., "Aircraft Fire Fighting In Three Minutes or Less," Industrial Fire World, 5 (1), February/March 1990, pp. 16-24. 6. Geyer, G.B., "Effect of Ground Crash Fire on Aircraft Fuselage Integrity," FAA Report RD-6946, Atlantic City, NJ, December 1969. 7. Geyer, G.B., "Evaluation of Aircraft Ground Firefighting Agents and Techniques," Tri-Service System Program Office for Aircraft Ground Fire Suppression and Rescue, Technical Report AGFSRS 71-1, Wright-Patterson AFB, OH, February 1972. 8. Eklund, T.I., and Sarkos, C.P., "The Thermal Impact of External Pool Fires on Aircraft Fuselages," Journal of Fire and Flammability, 11, July 1980, p. 231. 9. International Civil Aviation Organization, "Rescue and Fire Fighting Panel, Second Meeting, Montreal, 5-16 June 1972 Report," ICAO, Montreal, Quebec, Canada, 1972. 10. Federal Specification, "0-F-555b, Foam-forming Liquids, Concentrated Fire Extinguishing, Mechanical," March 11, 1964. 11. Military Specification, "Fire Extinguishing Agent, Aqueous Film-forming Foam (AFFF) Liquid Concentrate, Six Percent for Fresh and Seawater," MIL-F-24385 (Navy), November 21, 1969, superseding MIL-F-23905B. 12. Darwin, R.L., and Jablonski, E.J., "Full-scale Fire Test Studies of Seawater Compatible `Light Water' as Related to Shipboard Fire Protection," Department of Navy Report, Washington, DC, August 25, 1969. 13. Military Specification, "Fire Extinguishing Agent, Aqueous Film-forming Foam (AFFF) Liquid Concentrate, for Fresh and Seawater," MIL-F-24385F, 7 January 1992. 50 US00006790 14. Geyer, G.B., "Firefighting Effectiveness of Aqueous Film-forming Foam (AFFF) Agents," FAA Technical Report FAA-NA-72-48, prepared for the DOD Aircraft Ground Fire Suppression and Rescue Unit (ASD-TR-73-13), Washington, DC, April 1973. 15. Geyer, G.B., Neri, L.M., and Urban, C.H., "Comparative Evaluation of Firefighting Foam Agents," FAA Technical Report FAA-NA-79-2, Washington, DC, August 1979. 16. Jablonski, E.J., "Comparative Nozzle Study for Applying Aqueous Film-forming Foam on Largescale Fires," U.S. Air Force Report, CEEDO-TR-78-22, April 1978. 17. Miller, T.E., "Evaluation of Film-forming Fluoroprotein Foam," Mobil Research and Development Corporation Technical Report (unpublished). 18. Fiala, R., "Aircraft Postcrash Firefighting/Rescue," from AGARD Aircraft Fire Safety Lecture Series No. 123, June 1982. 19. Aubert, J.H., Kraynik, A.M., and Rand, P.B., "Aqueous Foams," S c ien tific A m e ric a , 19 (1), 1988, pp. 74-82. 20. Francen, V.L., "Fire Extinguishing Composition Comprising a Fluoroaliphatic and a Fluorine Free Surfactant," U.S. Patent 3,562,156, 1971. 21. Rosen, M.J., S u rfa c ta n ts a n d In te rfa c ia l P h e n o m e n a , John Wiley and Sons, NY, 1989, Chapters 1, 5 and 7. 22. Tuve, R.L., Peterson, H.B., Jablonski, E.J., and Neill, R.R., "A New Vapor-securing Agent for Flammable Liquid Fire Extinguishment," NRL Report 6057, March 1964. 23. Underwriters Laboratories Inc., F ire P r o te c tio n E q u ip m en t D ir e c to r y , 1993 Edition, Northbrook, IL. 24. Scheffey, J.L., Darwin, R.L., Leonard, J.T., Fulper, C.R., Ouellette, R.J., and Siegmann, C.W., "A Comparative Analysis of Film Forming Fluoroprotein Foam (FFFP) and Aqueous Film Forming Foam (AFFF) for Aircraft Rescue and Fire Fighting Services," Hughes Associates, Inc. Report 2108-A01-90 for the NFPA Aviation Committee, June 1990. 25. International Organization for Standardization, "Fire Extinguishing Media --Foam Concentrates --Part 1: Specification for Low Expansion Foam Characteristics for Top Application to Water Immiscible Liquids," ISO Draft Standard, ISO/DIS 7203-1, 1992. 26. Underwriters Laboratories, Inc., "Proposed Requirements for the Sixth Edition of the Standard for Foam Equipment and Liquid Concentrates," R e p o rt o f In d u stry A d v is o r y C o n feren ce , Northbrook, IL, September 1992. 27. U.S. Department of Defense, "Qualified Products List of Products Qualified Under Military Specification MIL-F-24385 Fire Extinguishing Agent, Aqueous Film Forming Foam (AFFF) Liquid Concentrate, for Fresh and Sea Water," QPL-25385-25, Washington, DC, 21 May 1992. 51 US00006791 28. Geyer, G.B., "Status Report on Current Foam Firefighting Agents," presented at the International Conference on Aviation Fire Protection, Interlaken, Switzerland, 22-24 September 1987. 29. Foster, J.A., "Additions for Hosereel Systems; Trials of Foam on 40 m2 Petrol Fires," Home Office Scientific Research and Development Branch Report 40/87, London, 1987. 30. Johnson, B.P., "A Comparison of Various Foams When Used Against Large-scale Petroleum Fires," Home Office Fire Research and Development Office, Pub. 2/93, 1993. 31. Foster, J.A., and Johnson, B.P., "The Use of Fire Fighting Foam in the UK Fire Service," F irst I n te r n a tio n a l C o n fe r e n c e on F ire S u p p re ssio n R e s e a r c h P r o c e e d in g s , Stockholm and Boras, Sweden, Swedish Fire Research Board, Stockholm and National Institute of Standards and Technology, Gaithersburg, MD, May 5-8-93, pp. 291-299, 32. Carey, W.M., and Suchomel, M.R., "Testing of Fire Fighting Foam," Underwriters Laboratories Report No. CG-M-1-81, Northbrook, IL, November 1980. 33. Thomas, M.D., "UK Home Office Research into Domestic Fire Fighting," F irs t In te rn a tio n a l C o n fe re n c e o n F ire S u p p re ssio n R e se a rc h P r o c e e d in g s , Stockholm and Boras, Sweden, Swedish Fire Research Board, Stockholm and National Institute of Standards and Technology, Gaithersburg, MD, May 5-8-93, pp. 283-289. 52 US00006792 Appendix A Comparison of the Physical and Chemical Properties of Protein-based and Aqueous Film-forming Foams A-l US00006793 BACKGROUND Attempts have been made to classify foam firefighting agents strictly on their physicochemical properties. This section documents testing of fundamental foam properties and compares results with standard fire tests. Except where noted, all tests were conducted in accordance with Revision C of the MIL SPEC, MIL-F-24385C. Variables of foam agents which could influence fire extinguishment and burnback performance include the following: a. Physical/chemical properties of foam solution (1) Foam bubble stability: Expansion and drainage (a) Water temperature (b) Water hardness (c) Water contamination, e.g., salt water (2) Fluidity (a) Viscosity of foam solution (b) Ability to form a film --spreading coefficient (i) Fuel type (ii) Fuel temperature b. Test methods/extinguishment (1) Application method (a) Fixed v. movable nozzle (b) Aspirating v. nonair-aspirating nozzle (i) Stream reach and pushing effect of hose stream (ii) Need to aspirate based on foam (c) Direct vs. indirect (i) Gentle (ii) Plunging (iii) Against-the-backboard A-2 US00006794 (2) Fuel Type (i) Vapor pressure (ii) Flashpoint (iii) Surface tension (b) Temperature (i) Initial (ii) Prebum time (3) Fire size --burning rate (effects of variable burning rate at less than 1 m diameter) (4) Pan configuration (a) Geometry (square vs. round) (b) Freeboard (hot edge effect) c. Environment (1) Wind (a) Flux to fuel surface (b) Effects on foam stream reach (2) Substrate (a) Smooth vs. rough (b) "Peeling11on water substrate The work described in this appendix is based on work performed by George Geyer of the FAA based on data presented at the International Conference on Aviation Fire Protection in Interlaken, Switzerland, 1987. The data were developed in an attempt to distinguish test methods and criteria for protein-based and film-forming foams. A-3 US00006795 DISCUSSION The firefighting effectiveness of the foam produced by the perfluorinated surfactants is enhanced by the aqueous fluorocarbon film, which floats on the surface of hydrocarbon fuels as it drains from the foam blanket. The mechanism whereby the fluorocarbon surfactants function as effective vapor securing agents is based upon their effect in reducing the surface tension of water and of their controllable oleophobic and hydrophilic properties. These properties provide a means for controlling the physical properties of water, enabling it to float and spread across the surface of a hydrocarbon fuel even though it is more dense than the substrate. This unique property led to the term "light water," which appeared in several of the early military specifications defining the properties of this class of agents. According to classical theoryA1 concerning the spreading of insoluble films on liquid surfaces, the following equation maintains SC = o - (w + 0 (A1) where SC = o= w= i= spreading coefficient of the aqueous fluorocarbon solution, surface tension of the fuel, surface tension of the aqueous film, and interfacial tension between fuel and the aqueous film. If the spreading coefficient has a value greater than zero {i.e., positive), the aqueous phase can spread spontaneously upon or "wet" the fuel. A coefficient below zero (i.e., negative) indicates that it cannot spread spontaneously. When the spreading coefficient is zero, the two liquids are miscible. Although this equation is applicable to pure liquids, there is wide variation possible when aqueous fluorocarbon films spread on a hydrocarbon fuel because of the variable oleophobic and hydrophobic properties of the fluorocarbon moieties. It is, therefore, appropriate to assess the interrelationship between firefighting effectiveness and the surface activity of the aqueous films produced by AFFF agents. The physical modifications of protein hydrolyzates, which may be accomplished by the addition of fluorocarbon surfactants, is summarized in figure 6 in the main text. In this diagram, fluoroprotein foams and aqueous film-forming fluoroprotein foams are indicated as lying in a variable position between protein foam on the left and aqueous film-forming foam on the right. If small quantities of suitable fluorocarbon surfactants are added to protein hydrolyzates, the resulting product may produce foam, which demonstrates good stability toward dry chemical powder, with improved oleophobicity and greater burnback resistance to aircraft fuels. If larger quantities of suitable fluorocarbons are incorporated into the basic protein hydrolyzate, the surface tension of the solution, which drains from the foam, may be lowered to a value which permits it to spread spontaneously across the surface of liquid hydrocarbon fuels. Under these conditions, the generic term, "fluoroprotein foam," would still apply, but the physical properties of the foam would approach or equal those of the aqueous film-forming foams. Foam liquid concentrates of this type are classified as film-forming fluoroprotein foams. A-4 US0000' PHYSICAL AND CHEMICAL PROPERTIES OF FOAM AGENTS. The chemical composition of 24 agents evaluated under this project is presented in tables A-l and A-2. Table A-l provides the composition of the purely synthetic aqueous film-forming foams while table A-2 presents the composition of those concentrates which are comprised either wholly or partially of a protein hydrolyzate. Tests to identify these properties were conducted in accordance with the MIL SPEC. The importance of these properties is described in table 9 of the main text. For example, chloride content is intended to be an indicator of corrosion potential to proportioning system pumps and equipment. Fluorine content is used in the MIL SPEC as a quality control indicator for each qualified agent. Refractive index is used as a method to determining proportioning accurately. CORROSIVITY OF FOAM AGENTS. There has recently been concern related to the corrosivity of foam agents when discharged on metal (aircraft) surfaces. The total quantity of halide permitted in the Type 3 percent and Type 6 percent aqueous film-forming foams in the MIL SPEC are 500 parts per million (ppm) and 250 ppm, respectively, when tested in accordance with ASTM D1821. However, other foam agents not manufactured in accordance with the military specification were found to contain very large quantities of halide salts. As a result, tests were conducted to determine the corrosive rate of seven foam firefighting agents against three common construction materials: cold rolled low carbon steel (UNS G101100), aluminum (1061), and stainless steel (304). The maximum permissible corrosion rate of a foam liquid concentrate exposed to steel (UNS G10100) under MIL-F-24385C is 1.6 miili-inches/year, but there are no maximum rates specified for aluminum or stainless steel. The results of the corrosion tests with seven foam agents and three construction metals are summarized in table A-3 and plotted in figure A-1. The metal corrosion rates are the averages of five individual tests performed with each foam liquid and metal combination. The corrosive rate on the cold rolled steel coupons produced by the seven foam agents is plotted in figure A-l along with their respective halide concentrations. An analysis of these data shows that the halide content of the synthetic-type AFFF agents is relatively low (i.e., from 13.9 to 1,285 mg/L) and that the corrosive rate is not proportional to the halide content. This result was unexpected and may involve the common ion effect in suppressing corrosion of the metal. However, the corrosion rate of the steel coupons was not proportional to the halide content (i.e., from 12,589 to 65,281 mg/L) of those foam agents which contain protein. Although the halide content of the seven foam agents varied widely (i.e., from 13.9 to 65,281 mg/L), none exceeded the maximum allowable corrosion rate of 1.5 milli-inches/year specified in MIL-F-24385C for steel. A-5 US00006797 TABLE A -l. PHYSIOCHEMICAL PROPERTIES OF AFFF CONCENTRATES Concentrate 3M Company Light water FC 206 CE 6% Light water FC 203 CE 3% Light water FC 201 CE 1% Light water FC 600 3%/6% Angus Fire Armour Tridol 6% Tridol 3% Ansul Fire Protection Ansute AFC3 6 % Ansulite AFC3A 3 % Ansulite 1% Ansulite ARC 3%/6% National Foam Systems, Inc. Aer O-Water 6% Aer-O-Water 3 % Aer-O-Water 3 % Military 3 % Universal 3%/6% Type of Foam Chloride Density 1luorine Refractive Solid Content @ 25C Content % Index Content % (mg/L) (g/mL) by Wt. PH @25C by Wt. AFFF-MIL AFFF-MIL AFFF AFFF-AR 11.7 31.5 109.0 1.025 1.026 1.097 1.023 1.03 2.02 8.42 1.34 8.52 1.3612 7.62 1.3774 8.32 1.3975 7.67 1.3545 4.3 6.5 22.5 6.5 AFFF AFFF 257.0 1285.0 1.010 1.042 0.538 0.650 7.38 1.3461 7.71 1.3656 3.5 10.69 AFFF-MIL AFFF-MIL AFFF AFFF-AR 13.9 13.9 15.3 1.007 0.487 7.31 1.3616 1.014 0.799 7.18 1.3657 1.029 2.62 7.21 1.3894 1.003 0.358 7.91 1.3589 1.75 3.92 10.50 3.84 AFFF 236.0 1.010 0.549 7.44 1.3468 AFFF 422.0 1.049 0.664 8.02 1.3674 AFFF-MIL 411.0 1.075 1.649 7.70 1.3586 AFFF-AR 1542.0 1.013 0.567 7.63 1.3503 3.29 15.03 19.73 7.01 TABLE A 2. PHYSIOCHEMICAL PROPERTIES OF PROTEIN CONTAINING CONCENTRATES Concentrate Angus Fire Armour Pelroseal 6% Petroseal 3% Alcoseal 3%/6% FP 570 6% FP 70 3% Nicerol 6% Nicerol 3% National Foam Systems, Inc. Aer-O-Film 3% XL-6 XL-3 Type of Foam Chloride Density Fluorine Refractive Solid Content @ 25C Content % Index Content % (mg/L) (g/mL) by Wt. pH @25C by Wt. FFFP FFFP FFFP-AR FPF FPF PF PF 54,178 65,281 2,827 47,702 37,527 41,944 62,197 1.151 1.170 1.081 1.125 1.148 1.108 1.149 0.273 0.361 0.387 0.041 0.068 0.007 0.003 6.94 1.3998 6.88 1.4180 6.49 1.3909 7.47 1.3925 7.19 1.4011 6.93 1.3866 6.48 1.4041 31.97 38.15 26.82 27.97 32.39 24.67 35.63 FFFP FPF FPF 2,210 12,748 21,589 1.146 1.128 1.131 0.495 0.075 0.091 7.75 1.3686 7.09 1.4141 6.97 1.4292 15.20 33.98 41.96 TABLE A-3. SUMMARY OF CORROSION TESTS Foam Agents Halide Content (mg/L) Steel (G10100) (mg) Weight loss (- ) Weight gain (+) Corrosion milli-inches/year maximum 1.5 Aluminum (6061) Weight loss ( ) Weight gain (+) Corrosion milli-inches/year Stainless Steel (304) Weight loss (--) Weight gain (+) Corrosion milli-inches/year 3M FC 203 CE 31.5 -49.47 0.644 3.92 None measurable 5.57 None measurable Angus Tridol 3% 1,285 Ansul AFC3A 13.9 National Foam AFFF 3% 422 Angus Petroseal 3% 65,281 Angus FP 70 37,527 National Foam XL3 21,589 7.56 -78.06 -36.66 -51.95 -110.67 -57.39 0.098 1.02 0.478 0.68 1.446 0.772 -2.27 0.107 +0.246 None measurable +0.11 0.0006 -1.172 0.08 0.076 0.01 --0.252 HJ.264 0.00006 0.0003 0.0032 1 0.0034 -3.86 0.154 -0.364 0.0048 -0.938 0.036 -0.366 0.0048 Maximum Value Under MIL-F-2438Sc - 1.25 - A Angus FP70 O Synthetic-Type Agents A Agents Containing Protein Corrosion Rate (milliinch/year) 1.00 O Ansul AFC 3A 0.75 - 3 3M FC203CE 0.50 _ ONFSAFFF3% A NFS XL3 A Angus Petroseal 3% 0.25 - - O Angus Tridol 3% 0.00 0 10000 20000 30000 40000 Chloride Content (mg/l) 50000 60000 70000 FIGURE A-l. CORROSION RATE OF FOAM FIREFIGHTING AGENTS AGAINST STEEL (UNS G10100) ca> VS. THEIR CHLORIDE CONTENT o o o oO00) o RELATIONSHIPS BETWEEN SPREADING COEFFICIENT, FLUORINE CONTENT ANO FIRE PERFORMANCE. Film-forming foams produce a stable aqueous fluorocarbon film on the surface of hydrocarbon fuels. The ability to form a film, as indicated by a positive spreading coefficient, is dependent on the foam agent, the test fuel, and the fuel temperature. Baseline data for spreading coefficients, based on the MIL SPEC test criteria (ASTM D1331) with cyclohexane as the test fuel, is shown in tables 10 and 11 of the main report. Protein foams do not form a film and have a negative spreading coefficient. For example, Angus Nicerol 3%, a protein foam, has a spreading coefficient of --30.63. Angus FP 70 3% and National XL3 3%, both fluoroprotein foams, have spreading coefficients o f --12.69 and --12.44, respectively, on cyclohexane. These foams must be highly expanded so that they float on the fuel surface, i.e., have a density less than the fuel. As noted in the main report, there is no 1:1 correlation between spreading coefficient and fire extinguishment and bumback time when cyclohexane is used as the test fuel. EFFECTS OF TEST FUEL ON SPREADING COEFFICIENT. Experiments were conducted to determine the effect of differences in the values of the spreading coefficient using various test fuel types. Six aqueous film-forming foam agents, none of which were MIL SPEC products, were used in the comparison. The profiles presented in figure A-2 show the spreading coefficient for the six different aqueous film-forming foams when tested against n-heptane, cyclohexane, and Avgas. The surface tension of the test fuels show that n-heptane (19.11 dynes/cm) and Avgas (19.20 dynes/cm) have almost identical values while that for cyclohexane (22.75 dynes/cm) is significantly higher. The spreading coefficient data for six AFFF agents with cyclohexane indicate that four agents (Angus Alcoseal, 3M FC600, Angus Petroseal, and 3M FC201) failed to meet the minimum requirement of +3 under MIL-F-24385C while two agents (National Aer-OFilm, and Angus Tridol 3%) exceeded the minimum requirement. The spreading coefficient of the same agents evaluated against n-heptane and Avgas showed that only two had positive values (National Aer-O-Film and Angus Tridol) while the remaining four (Angus Alcoseal, Angus Petroseal, 3M FC 600, and 3M FC 201) had negative spreading coefficient values. Each of the six aqueous film-forming foam agents was tested for fire performance employing the 50 ft2 (4.6 m2) fire test procedure under MIL-F-24385C using n-heptane, Avgas, and motor gasoline as the test fuels. The maximum fire extinguishing time for this procedure, using motor gasoline (VV-G-1690) is 50 seconds using the standard 2 gpm (7.6 Lpm) nozzle. The data shown, in figure A-3, shows that there is no direct correlation between the value of the spreading coefficient and the time to extinguish the n-heptane and Avgas fires using Angus Alcoseal, Angus Petroseal, 3M FC 600, and National Aer-O-Film. Although Angus Alcoseal and Angus Petroseal both have negative spreading coefficients with these fuels, they were able to extinguish the n-heptane and Avgas fires within 50 to 70 seconds. The 3M FC 600 agent, which also has a negative spreading coefficient with these fuels, extinguished these fires in less than 40 seconds. However, National Aer-O-Film, which has a small positive spreading coefficient with n-heptane and Avgas, required between 60 and 70 seconds for extinguishment. A -10 US00006802 8n Spreading Coefficient 6- 43 2 -{ -2 - Pass (MIL-F-24385C) Will Form Film f on Hydrocarbons I Will Not Form F ilin i Hydrocarbons f -4 -6 Angus Alcoseal T Angus 3% Petroseal 3M FC-600 Fuel Surface Tension n-Heptane Cyclohexane AVGAS 100/130 fdvnes/cm ) 19.11 22.75 19.20 National Aer-o-film 1 Angus 3% Tridol ------ i------- 3M FC-201 FIGURE A-2. SPREADING COEFFICIENTS FOR FILM-FORMING FOAM AGENTS ON THREE TEST FUELS 120 100 Fuel Tvdo o n-Heplane Fire Extinguishing Time Motor Gasoline (W -G-1690) * " -- Fire Control Time A AVGAS 100/130 80 60 40 20 0 I I ----------- !----------- ----------- 1------------ i Angus Angus 3M FC400 N ational Angus Alcoseal 3% Petroseal A sr-o-film 3* T ridol Foam Agents URE A-3 EFFECT OF FUEL TYPE OF FIRE PERFORMANCE USING THE MIL-F-24385C 50 SQUARE FOOT FIRE TEST From the results from these experiments, it is speculated that the spreading coefficient, which was developed by W.D. HarkinsAI for pure liquid systems, does not apply in all cases to complex aqueous fluorocarbon systems. The oleophobicity demonstrated by the aqueous film-forming foams may be responsible, in part, for the fire extinguishing effectiveness of those agents which demonstrate a negative spreading coefficient on some test fuels. SPREADING RATES OF AQUEOUS FLUOROCARBON FILMS ON JET A FUEL. In the previous section, it was demonstrated that spreading coefficient alone was not a reliable indicator of fire extinguishing performance. It is believed that the extinguishing effectiveness of the film-forming foams is attributable, at least in part, to the fluidity of the foam solution on the fuel surface. The rate of spread and the stability of the aqueous film is a contributing factor in the rapid control/extinguishment characteristics of these agents on hydrocarbon fuel fires. The FFFP concentrates contain a protein hydrolyzate as the foam stabilizer while the AFFF concentrates employ a water soluble polymer as the foam stabilizing agent. The protein derivative in the FFFP formulation tends to produce a more viscous and slower draining foam than the synthetic polymer in the AFFF composition. A knowledge of the relative film spreading rate of each aqueous film-forming composition may be of value in understanding the fire extinguishing characteristics of these agents. A laboratory apparatus was developed for measuring the spreading rates of aqueous films on aviation fuels. This apparatus and the test procedure is described in reference A2. The film spread rate is determining by discharging four milliliters (mL) of foam solution down an inclined trough onto a pan with Jet A fuel. The foam solution is discharged at a uniform rate of 0.10 mL/s. The distance traveled by the contiguous aqueous film is recorded at appropriate time intervals. The film spread rates obtained for the AFFF and FFFP agents on Jet A fuel are summarized in table A-4. The total distance traveled by the aqueous fluorocarbon films down the length of the trough, before lensing and breakup of the film occurred, was approximately 90 centimeters for both the AFFF and FFFP agents. Although the data do not correlate directly with the spreading coefficient of the agents with cyclohexane (different fuel), the magnitude of differences between the AFFF and FFFP spreading rates do correlate with the extinguishment data in tables 10 and 11. The spreading rate of AFFF is approximately double that of the FFFPs. The control and extinguishment times of these AFFFs were roughly 30 to 50 percent less than that of the FFFPs using the 50 ft2 (4.6 m2) MIL SPEC fire test. FIRE PERFORMANCE AS A FUNCTION OF SPREADING COEFFICIENT AND FLUORINE CONTENT. Because of the wide variation in the composition of the aqueous film-forming foam agents currently being manufactured, a comparison of agent fluorine content of the film-forming agents was conducted. Figure A-4 shows the value of the spreading coefficient (SC) as a function of the agent's fluorine content. The minimum value of the SC under Military Specification MIL-F24385C is +3, accordingly the dashed horizontal line (figure A-4) separates those agents which meet the requirement from those which do not. A -13 US00006805 TABLE A-4. RELATIVE FILM SPREAD RATES OF THE FILM FORMING AGENTS ON JET A FUEL Agent Type FFFP Angus Petroseal 3% FFFP Angus Petroseal 6% AFFF Angus Tridol 6% AFFF NFS Aer-O-Water 6% Film Spread Rate (cm/s) 0.85 0.95 2.29 2.22 Tables 10 and 11 presented the fire performance for each AFFF agent shown in figure A-4 using the 50 ft2 (4.6 m2) fire conducted in accordance with MIL-F-24385C, Of the 18 agents tested, only eight met all of the fire test requirements of the military specification. Of the 18 agents analyzed, five had a SC below three while 12 had an SC greater than three, and one agent was considered "borderline11with an SC value of 3.01. Of the 13 agents which demonstrated an SC above three, only five passed all of the requirements of MIL-F-24385C while three of five agents with SCs below three passed all of the fire test requirements of the military specification. It can be concluded that spreading coefficient alone is not a reliable indicator of fire and bumback performance. There is also no correlation of the fluorine content with the spreading coefficient. A -14 US00006806 AnsulUa AFC 3V6% \ Trido! 3% JM FC M J 3% \ NFS 3*/6% "" N TM f AnsullteAFC 3% " NFS3%FFFP PetroM al <% NFS 3% (MIL) A nsullteA FC 1% AnsulHe AFC 6% 3M FC 206 6% ____________ # _____________ 3M FC 600 3%K% Petroteal 3% NFS 6% AFFF Atcoseel 3%/6% Pass -f Fail 3M FC 2011% Pass (MIL-F-24385C) Fire Test I I I I I 1 1 I 1 1 I I I i I I I I I I I I I I I I I I 1 I I n I I I I I I I I I I II IT I T 1 I T I I T II I I I I II M I I I I II M II II I I I I I I I I I T ' M 012345678 9 Fluorine Content (%) FIGURE A-4. SPREADING COEFFICIENT AS A FUNCTION OF FLUORINE CONTENT REFERENCES Al. Harkins, W.D., "The Physical Chemistry of Surface Films," Rheinhold Publishing Corporation, 1952. A2. Geyer, G.B., Neri, L.M., and Urban, C.H., "Comparative Evaluation of Firefighting Foam Agents," FAA Technical Report FAA-NA-79-2, Washington, DC, August 1979. A-16 US00006808 Appendix B Summary of NRL Tests B-l US00006809 INTRODUCTION Bench-scale, 28 ft2 (2.6 m2) and 50 ft2(4.6 m2) tests were performed by NRL in accordance with Revision C of the MIL SPEC. Two AFFF agents were tested, both 6 percent products from the QPL. A commercial 6 percent FFFP product was also tested. The following is a summary of testing from the Naval Research Laboratory. For complete details and analysis, see reference 24. EQUIPMENT AND PROCEDURES SPREADING COEFFICIENTS. Reagent grade cyclohexane and 99 percent pure n-heptane were used as the reference fuels. Surface tension and interfacial tension were measured in accordance with ASTM D-1331, "Standard Test Methods for Surface and Interfacial Tension of Solutions of Surface-Active Agents." A du Nouy tensiometer, having a torsion balance with a 4- or 6-cm circumference platinum-iridium ring, was lowered into the liquid and slowly pulled out until the liquid detached from the ring's surface. The force recorded at the point where this separation occurred was recorded as the surface tension (dynes/cm) of the pure liquid. Similarly, the interfacial tension was the measurement of tension when the ring was pulled through the boundary layer between two liquids. FILM FORMATION AND SEALABILITY. Two methods were used to measure the film formation and sealability of foams. The first method, in accordance with Revision C of the MIL SPEC, used a measured amount of expanded foam applied over a fuel bed of cyclohexane in a 1000 mL beaker. An inverted steel mesh cone was inserted in the cylinder to push away the foam from the fuel surface. Residual foam was cleared from the fuel surface in the center of the cone, and film producing liquid was allowed to seep through the mesh cone. After one minute, a pilot flame was passed over the fuel surface at a height of 0.5 in. (1.27 cm). The test method permits a small flash, but no sustained ignition of the fuel may result. The second method used involved a flat-head wood screw placed in a petri dish filled with nheptane. Using a microsyringe, a measured amount of unexpanded foam solution was applied to the tip of the screw at a rate of one droplet per second. Two minutes after the initiation of solution application, a pilot flame was passed over the fuel surface at a height of 0.5 in. (1.27 cm). The pass/fail criteria was the same as the Revision C criteria. EXPANSION AND DRAINAGE. The tests were conducted in accordance with the method outlined in the MEL SPEC, which is similar to Method A in NFPA 412. A 2 gpm (7.6 Lpm) nozzle was utilized to discharge expanded foam onto an inclined backboard. From the backboard, the foam was collected in 1000 mL graduated cylinders. After the cylinders were filled, they were removed and a timer was started. The cylinder was then cleaned off and weighed, and the total volume of solution collected in the cylinder was calculated (where 1 mL solution = 1 g solution). B-2 US00006810 The expansion ratio was determined using the following equation: E.R. 1000 W.s o i n (Bl) where E.R. = Wso]n = expansion ratio, and weight of solution in cylinder (g). The 25 percent drainage time is the time for 25 percent of the total liquid to drain from the foam sample. The 25 percent drainage volume was determined by using the weight of the solution in the cylinder (W,oln above). The 25 percent drainage time was recorded when the liquid level in the sample reached the 25 percent drainage volume. Expansion ratio and drainage time tests were conducted with both fresh and simulated sea water solutions. FLUORINE CONTENT. Fluorine content was determined using the ion analyzer method described in the MIL SPEC. MIL SPEC FIRE TESTS. Fire tests were performed with the foam agents in accordance with MIL-F-24385. For the 28 ft2 (2.6 m2) tests. Revision C was used. Motor gasoline in accordance with Federal Specification VV-G-1690 was used and the fresh water foam was discharged through an air aspirating nozzle at a rate of 2 gpm (7.6 Lpm). This resulted in an application rate of 0.071 gpm/ft2 (2.9 Lpm/m2). In reporting the 28 ft2 (2.6 m2) fire test results, two nonstandard methods of determining fire knockdown were used. Both methods use the radiometer setup described for the 28 ft2 (2.6 m2) test in the proposed Revision D of the MIL SPEC. Radiant heat flux measurements were recorded at the 10-, 15-, 20- and 25-second time intervals. The reduction in heat flux was calculated by dividing the flux level at each time interval by the peak flux level at the time agent application was begun. This ratio was then converted to a "percent extinguished" value. The 25-second summation is the sum of these percentage values for all four time intervals. The 90 percent control time is the time at which the radiant flux was reduced to a level which corresponds to a 90 percent decrease in fire area. The method of calculation is similar to that used to determine the 25 s summation value, except that the calculations are performed for all data points starting at the start of agent application. A detailed description of these estimating techniques is contained in reference 24. The burnback resistance for the 28 ft2(2.6 m2) test is described by the 15 percent burnback time. This time was also calculated from radiometer data collected during the test. It is based on a 300 percent increase in flux level over an initial background level. The initial background flux level is determined by averaging the values recorded for the time period 1 to 3 min after the burnback pan was lit. As the test progressed, the flux level was continually checked. When the flux level B-3 US00006811 reached a value that was 300 percent greater than the initial background value, the time was recorded as the 15 percent burnback time. The 50-ft2 (4.6 m2) fire tests were performed in accordance with Revision C of the MIL SPEC. Seawater foam solutions were discharged through the 2-gpm (7.6 Lpm) nozzle on motor gasoline and n-heptane fires. The resulting application rate was 0.04 gpm/ft2 (1.6 Lpm/m2). The 40 second summation was the sum of the percent fire area extinguished at 10, 20, 30 and 40 seconds after the initiation of firefighting. Twenty-five percent burnback time was recorded as the time when 25 percent of the test area was reinvolved in fire after the burnback pan was placed in the pool. NONAIR-ASPIRATED NOZZLE TEST. The nonair-aspirated test was performed using a 50-ft2 (4.6 m2) n-heptane pool fire. A nonair aspirating spray nozzle, Grinnell Model D4A, was modified with an orifice plate to flow 5.5 gpm (20.8 Lpm). This resulted in an application rate of 0.11 gpm/ft2 (4.6 Lpm/m2). This nozzle is normally used as a fixed water spray nozzle. The expansion and drainage characteristics were determined using the test method described in the MIL SPEC, substituting the D4A nozzle flowing 5.5 gpm (20.8 Lpm) for the MIL SPEC 2-gpm (7.6 Lpm) nozzle. The 50-ft2 (4,6 m2) fire was attacked manually by a firefighter. The attack was aggressive until approximately 90 percent control was achieved. At that time, the nozzle was backed off so that there was a gentler application. The fire was totally extinguished by allowing the foam to spread and fill in the remaining fire area with no direct application to the flaming area. The subsequent burnback test followed the 50-ft2 (4.6 m2) MIL SPEC test procedure. Agent application time totalled 90 s. RESULTS AND ANALYSIS SPREADING COEFFICIENTS. The values for surface tension, interfacial tension, and spreading coefficient are presented in table B-l. The AFFF had a higher surface tension and a lower interfacial tension, compared to the FFFP. The commercial FFFP had a negative spreading coefficient when tested with n-heptane. No across-the-board correlations between spreading coefficients, fire control, extinguishment, and burnback resistance are apparent. As such, the spreading coefficient data alone cannot be used as relative predictors of fire performance. FILM FORMATION AND SEALABILITY TESTS. The results of the Film Formation and Sealability tests are presented in table B-2, For both procedures, an agent was considered to have passed if the pilot flame could be moved one time slowly from one side of the dish or container to the other and then back again, without producing sustained ignition. If ignition did not occur, the flame passage over the fuel surface was continued 4-5 times or until ignition occurred. B-4 US00006812 TABLE B-l. SPREADING COEFFICIENTS Agent with cyclohexane MIL SPEC AFFF #2 Commercial FFFP with n-heptane Fuels MIL SPEC AFFF #2 Commercial FFFP Cyclohexane n-heptane Surface Tension (dynes/cmt Interfacial Tension (dynes/cm) Spreading Coefficient 17.45 16.71 1.80 5.42 5.40 2.52 17.45 16.71 2.16 5.51 0.04 -2.57 24.65 19.65 TABLE B-2. RESULTS OF FILM FORMATION AND SEALABILITY TESTS Agent MIL SPEC 6% AFFF #2 Commercial FFFP Test Fuel n-heptane Cyclohexane n-heptane Cyclohexane Results passed passed failed passed NI = sustained ignition did not occur after 4-5 passes of the flame. Number of Passes with Flame to Ignite 2 NI <1 NI In tests conducted in accordance with the Revision C test procedure, all of the agents passed. In no case was ignition sustained with 4-5 passes of the flame. This was expected since the spreading coefficients of all the agents on cyclohexane were significantly positive (all >2,5), This clearly demonstrates the ability of the agents to produce a film (on cyclohexane) from solution draining out of the expanded foam blanket, an important characteristic if the foam blanket is disturbed. In the n-heptane test, the spreading coefficient of the commercial FFFP was negative (--2.67). The FFFP did not pass the modified film and seal test using n-heptane film and seal test. EXPANSION RATIO AND DRAINAGE TIME. The expansion ratio and 25 percent drainage time values are used to characterize the quality of the foam produced. The expansion ratio is a measure of the solution's ability to form a stable bubble structure from entrained air. Drainage time is a measure of how durable the bubble B-5 US00006813 structure is and the rate at which solution is being released from the bubbles. These values obtained in expansion and drainage testing for a given agent are dependent on the discharge device, collection method, temperature of the agent, type of water used to mix the solution, and the configuration of the collection container. The results of the expansion ratio and 25 percent drainage time tests are presented in table B-3. Data are given for both fresh water and simulated sea water solutions. Drainage time is important to bumback resistance since it is the foam blanket which supplies the film forming solution to the fuel surface. If the foam blanket breaks down too quickly, then the film is exposed to the reignition source and evaporates. The relative rankings of the agents based on fresh water 25 percent drainage times and 28 ft2 fire bumback test results correspond with one another. TABLE B-3. EXPANSION AND DRAINAGE TEST RESULTS FOR FRESH AND SALT WATER SOLUTIONS Agent MIL SPEC AFFF MIL SPEC #1 Averages MIL SPEC #2 FFFP Averages Commercial FFFP Averages Fresh Water Expansion Ratio (: 1) 25% Drainage Time (s) 7.5 288 7.8 281 7.7 301 7.7 253 7.7 265 7.8 283 7.7 278.5 7.4 271 7.7 280 7.7 255 7.4 288 8.2 242 M 266 7.8 267.0 7.4 283 6.6 249 7.0 236 1 2 214 7.1 245.5 Seawater Expansion Ratio (:1) 25% Drainage Time (s) 7.5 238 7.5 248 8.2 301 8.5 270 ---- -- -- 7.9 270.0 7.2 251 7.1 269 7.7 211 7.8 245 ---- ---- 7.5 244.0 7.2 254 7.2 257 7.1 264 6J) 257 7.0 258.0 B-6 US00006814 FLUORINE CONTENT. The intent of the requirement in the MIL SPEC to report fluorine content is to provide a quality control measurement for purchasing purposes. There is currently no minimum fluorine content requirement contained in the MIL SPEC. The fluorine content of a product is determined at the time of qualification, and is then checked for each lot to be purchased. The type of fluorosurfactant will impact on fire test results as significantly as the amount will. Table B-4 reports the results of fluorine content. It can be seen that there is no direct correlation between fluorine content and extinguishment performance or burnback resistance. This is in agreement with the findings by the FAA. TABLE B-4. FLUORINE CONTENT OF AFFF AND FFFP Fluorine Content by Weight 0.11 0.61 0.42 Agent Description 6% FFFP, Commercial FFFP, purchased in 1989 MIL SPEC Agent #1, Date of Manufacturer: 5/1985, Lot 557 MIL SPEC Agent #2, Date of Manufacture: 10/1988, Lot X18044 MIL SPEC FIRE TESTS. Fire test results are reported in tables B-5 and B-6. Extinguishment application density, which normalizes the results by eliminating the time element, is used for comparative purposes. The data show that across the board the average 90 percent control, 100 percent extinguishment, and 25 percent bumback times for the MIL SPEC agents are superior to the commercially available FFFP agent tested. The knockdown times, represented by 90 percent control and the 25- and 40second summation values, are relatively close. In the 28 ft2 (4.6 m2) and 50 ft2 (2.6 m2) nheptane tests, the relatively small absolute differences in 100 percent extinguishment times (9-15 seconds) result in large (31 percent) differences in extinguishment application densities. The burnback performance of the AFFFs in the 50 ft2 (2.6 m2) and 50 ft2 (4.6 m2) n-heptane test series exceed the FFFP by 17-30 percent. These data are consistent with the previously unreported NRL data (reference 24) and the FAA data. NON-ASPIRATED NOZZLE TEST. The results of the nonaspirated test are shown in table B-7. The test was found to be a very challenging fire, particularly in terms of total extinguishment. With both AFFF and FFFP, there were test runs where the fire was not totally extinguished after 90 seconds of agent application. In the tests where total extinguishment was achieved, the data show that knockdown times, as indicated by the 40 s summation value, are nearly the same, and that the AFFF had a better extinguishment time. With the FFFP, the fire was not extinguished until the agent was shut off and the foam sealed the remaining fire. AFFF again showed better bumback resistance. These tests showed that FFFP can be used through a nonair-aspirated discharge device to extinguish a B-7 US00006815 hydrocarbon pool fire. Again, MIL SPEC AFFF was superior in terms of fire control, extinguishment, and burnback resistance. B-8 US00006816 TABLE B-5. REVISION C MIL SPEC 28 ft2 (50 m2) Fire Tests with MIL SPEC AFFF AGENTS AND FFFP Agent MIL SPEC AFFF #1 25 s Summation 312 343 310 326 90% Control Time (s) 16 16 17 16 Observed 100% Extinguishment Time (s) 23 24 23 24 Calculated 15% Burnback Time (s) b 514 563 552 M IL SPEC AFFF #2 Overall Averages Commercial FFFPb Average 317 311 320 277 252 264.5 16 il 17 21 li 21.0 27 531 29 514 27 540 36 419 35 412 35.5 415.5 a Tests were conducted with Mogas and fresh water solutions. Test not performed because excessive foam blanket depth extinguished fire in burnback pan. Extinguishment Application Density (gal/ft2 (17m2)) 0.027 0.029 0.027 0.029 (1.12) (1.16) (L12) (1.16) 0.032 (131) 0.035 (1.41) 0.032 (1.31) 0.043 (1.75) 0.042 (1-70) 0.042 ( L 7 2 ) Agent with Mogas MIL SPEC AFFF #2 (Average of 4 Tests) Commercial FFFP (Average of 2 Tests) with n-heptane MIL SPEC AFFF #2 (Average of 4 Tests) Commercial FFFP TABLE B-6. MIL SPEC 50 FT2 (4.6 M2) FIRE TESTS 40 s Summation (%) 318 295 100% Extinguishment Time (s) 53 55 Observed 25% Burnback Time (s) 374 354 Extinguishment Application Density (gal/ft2 (L/m2)) 0.035 (1.43) 0.037 (1.49) 319 48 315 63 450 0.032 (1.29) 383 0.042 (1.71) Agent MIL SPEC AFFF #2 Commercial FFFP TABLE B-7. NONAIR-ASPIRATED NOZZLE TESTS (n-heptane, 50 ft2 (4.6 m2), 5.5 gpm (20.1 Lpm), 0.11 gpm/ft2 (4.5 Lpm/m2)) 40 s Summation (%) 225 205 100% Extinguishment Time (s) 73 93 25% Bumback Time (s) 351 281 Appendix C Small- and Large-scale Test Data C-l US00006819 TABLE C-l. SUMMARY OF TEST DATA USED FOR CORRELATION BETWEEN SMALL- AND LARGE-SCALE TESTS Foam AFFF AFFF AFFF AFFF AFFF AFFF AFFF AFFF AFFF AFFF Protein AFFF AFFFb FFFP AFFF AFFF AFFF Application Rate (gpm/fT) 0.02 0.02 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.04 0.04 0.04 0.04 Test Area (ft2) 3525 3525 3525 4000 9000 4,000 8,000 9,000 10,580 15,386 9,000 50 50 50 4,400 4,400 6,241 Fuel JP-5 JP-5 JP-5 JP-4 JP-5 JP-4 JP-4 JP-5 JP-5 JP-4 JP-5 Gasoline Avgas Gasoline JP-5 Avgas Jet A Nozzle (AA/NAA) NAA AA AA NAA AA AA NAA AA AA AA AA AA AA AA AA AA AA Control Time (s) 38 39 32 21 46 30 61 37 66a 70 42 25.6a 32 38.6a 44 38 26 Specific Control Time (s-fU) 0.0108 0.0111 0.0091 0.0053 0.0051 0.0075 0.0076 0.0041 0.0062 0.0045 0.0047 0.5120 0.6400 0.7720 0.0100 0.0086 0.0042 Control Application Density (gal/ft3) 0.013 0.013 0.011 0.007 0.015 0.015 0.031 0.019 0.033 0.035 0.021 0.017 0.021 0.026 0.029 0.025 0.017 Referenee Darwin Darwin Darwin Jablonski Tuve Jablonski FAA-AFFF Tuve Darwin FAA-AGFSRS Tuve Scheffey Scheffey Scheffey Tuve Tuve FAA US00006820 a Average of multiple tests b Non-MIL SPEC AFFF TABLE C -l. SUMMARY OF TEST DATA USED FOR CORRELATION BETWEEN SMALL- AND LARGE-SCALE TESTS (Continued) Foam FFFP AFFF AFFF AFFF AFFF AFFF AFFF AFFF AFFF AFFF FPF P P FPF AFFF AFFFb AFFFb Application Rate (gpm/ff) 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.06 Test Area (ft2) 6,241 8,000 8,000 8,000 8,000 6,000 8,000 15,386 16,000 16,000 16,000 15,386 16,000 50 1,000 1,000 1,000 Fuel Jet A JP-4 JP-4 JP-4 JP-4 JP-5 Avgas JP-4 Jet A Jet A Jet A JP-4 Jet A Gasoline Avgas Avgas Avgas Nozzle (AA/NAA) AA NAA NAA AA AA AA AA AA AA NAA AA AA AA AA NAA NAA NAA Control Time (s) 35 24 58* 36.5 44.5 46 56 62 28* 24* 54* 118 46* 98* 17a 16 26 Specific Control Time (s-ff2) 0.0056 0.0030 0.0073 0.0046 0.0056 0.0077 0.0070 0.0040 0.0018 0.0015 0.0034 0.0077 0.0029 1.9600 0.0170 0.0160 0.0260 Control Application Density (gal/ft2) 0.023 0.016 0.048 0.030 0.037 0.038 0.047 0.052 0.023 0.020 0.045 0.098 0.038 0.098 0.017 0.016 0.026 Reference FAA Jablonski FAA-AFFF Jablonski FAA-AFFF FAA-AFFF FAA-AFFF FAA-AGFSRS FAA-COMP FAA COMP FAA-COMP FAA-AGFSRS FAA-COMP FAA NRL Scheffey Scheffey a Average of multiple tests b Non-MIL SPEC AFFF TABLE C-l. SUMMARY OF TEST DATA USED FOR CORRELATION BETWEEN SMALL- AND LARGE-SCALE TESTS (Continued) Foam AFFF P AFFF AFFF AFFF P P AFFF AFFFb FFFP P AFFF AFFFb AFFFb FFFP P AFFFb Application Rate (gpm/ft2) 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.07 0.10 0.10 Test Area (ft2) 3,525 3,525 4,000 4,400 4,400 4,400 4,400 7,850 431 431 7,850 28 28 28 28 50 602 Fuel JP-5 JP-5 JP-4 Avgas JP-5 JP-5 Avgas JP-4 Gasoline Gasoline JP 4 Gasoline Avgas Avgas Gasoline Gasoline Gasoline Nozzle (AA/NAA) AA AA AA AA AA AA AA AA AA AA AA A AA AA A AA AA Control Time (s) 28 35" 45* 19 18 25 57 40 73" 76" 65 17.3* 23 26 27 75" 51" Specific Control Time ( s - f t 2) 0.0079 0.0099 0.0113 0.0043 0.0041 0.0057 0.0130 0.0051 0.1694 0.1763 0.0083 0.6179 0.8214 0.9286 0.9643 1.5000 0.0847 Control Application Density (gal/ft2) 0.028 0.035 0.045 0.019 0.018 0.025 0.057 0.040 0.073 0.076 0.065 0.020 0.027 0.030 0.032 0.125 0.085 Reference Darwin Darwin FAA-AFFF Tuve Tuve Tuve Tuve FAA-AGFSRS SRDB SRDB FAA AGFSRS Scheffey Scheffey Scheffey Scheffey FAA Johnson US00006822 ' Average of multiple tests h Non-MIL SPEC AFFF TABLE C-l. SUMMARY OF TEST DATA USED FOR CORRELATION BETWEEN SMALL- AND LARGE-SCALE TESTS (Continued) Foam AFFFb FFFP FFFP AFFF FFFP AFFF AFFF AFFF AFFF AFFF AFFF AFFF AFFF FPF P AFFF AFFF Application Rate (gpm/fr) 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 Test Area (ft3) 602 602 602 2,500 2,500 2,666 2,666 2,666 3,525 3,525 4,000 4,000 7,850 7,850 7,850 8,000 8,000 Fuel Gasoline Gasoline Gasoline Jet A Jet A JP-4 JP-5 Avgas Avgas JP-4 JP-4 JP 4 JP-4 JP-4 JP-4 Jet A Jet A Nozzle (AA/NAA) AA AA AA AA AA AA AA AA AA AA AA NAA AA AA AA AA NAA Control Time (s) 51" 58" 63" 9.5" 8.6" 36" 52 52 43" 35" 36.5" 38" 21" 35 41 16.5" 16" Specific Control Time (s-ft3) 0.0847 0.0963 0.1047 0.0038 0.0034 0.0135 0.0195 0.0195 0.0122 0.0099 0.0091 0.0095 0.0027 0.0045 0.0052 0.0021 0.0020 Control Application Density (gal/ft2) 0.085 0.097 0.105 0.016 0.014 0.060 0.087 0.087 0.072 0.058 0 061 0.063 0.035 0.058 0.068 0.028 0.027 Reference Johnson Johnson Johnson FAA FAA FAA-AFFF FAA-AFFF FAA-AFFF Darwin Darwin FAA-AFFF FAA-AFFF FAA-AGFSRS FAA-AGFSRS FAA-AGFSRS FAA-COMP FAA-COMP US00006823 ' Average of multiple tests h Non-MIL SPEC AFFF TABLE C 1. SUMMARY OF TEST DATA USED FOR CORRELATION BETWEEN SMALL- AND LARGE-SCALE TESTS (Continued) Poam FPF P AFFF P AFFF AFFF AFFF AFFF AFFF AFFF P P AFFF AFFF P AFFF Application Rate (gpm/ft2) 0.10 0.10 0.13 0.13 0.15 0.15 0.15 0.15 0.18 0.18 0.18 0.18 0.20 0.20 0.20 0.36 Test Area (ft2) 8,000 8,(XX) 3,846 3,846 1,666 1,666 1,666 4,000 1,400 1,400 1,400 1,400 315 3,846 3,846 700 Fuel Jet A Jet A JP-4 JP-4 JP-4 JP 5 Avgas JP-4 JP-5 Avgas JP-5 Avgas JP-5 JP-4 JP-4 Avgas Nozzle (AA/NAA) AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA Control Time (s) 21a 20.5a Specific Control Time (s-ft2) 0.0026 0.0026 35 0.0091 58 0.0151 29a 35 51 24.5a 0.0174 0.0210 0.0306 0.0061 8.5a 0.0061 14 0.0100 I I a 0.0079 22 0.0157 8 0.0254 21 0.0055 25 0.0065 9 0.0129 Control Application Density (gal/ft2) 0.035 0.034 0.076 0.126 0.073 0.088 0.128 0.061 0.026 0.042 0.033 0.066 0.027 0.070 0.083 0.054 Reference FAA-COMP FAA-COMP FAA-AGFSRS FAA AGFSRS FAA-AFFF FAA-AFFF FAA-AFFF FAA-AFFF Tuve Tuve Tuve Tuve Darwin FAA-AGFSRS FAA-AGFSRS Tuve US00006824 ' Average of multiple tests 1 Non-MIL SPEC AFFF TABLE C -l. SUMMARY OF TEST DATA USED FOR CORRELATION BETWEEN SMALL- AND LARGE-SCALE TESTS (Continued) Foam AFFF P P Application Rate (gpm/fr) 0.36 0.36 0.36 Test Area (ft2) 700 700 700 Fuel JP-5 Avgas JP-5 Nozzle (AA/NAA) AA AA AA Control Time (s) 6 12 9 Specific Control Time (s-ft2) 0.0086 0.0171 0.0129 Control Application Density (gal/ft2) 0.036 0.072 0.054 Reference Tuve Tuve Tuve Average of multiple tests h Non-MIL SPEC AFFF