Document pBVn8kavD0prxGj9JJEqGVmLj

Kdward V Iloward S y/ \ I !<' I J l )\ I I 1 ! ' U,.,t .,n,l ......... Ml,,.. V-- v in .iHiIi.iii til Hill iihI Kn.ivtlii.il In, bt.er-v Iv* Go: (>n< ( .jsj.uii ri.i/.i. \ki< 11 ()|ih* inos n(H) \ A.\ 'l\h- t.. PRO Members 11<>m Dan Stanowick 'iibjcci. Article reprint (late: January 31, 1991 copies to: Roy Gottesman Nora Jacobs Enclosed for your files are copies of the Fire Journal article we decided to reprint at our recent meeting. CTL027231 HREPURNAL NOVEMBER/DECEMBER 1990 Is PVC Piping Firesofe? Joseph B. Zicherman, PhD CTL027232 A Division of The Society of The Plastics Industry, Inc. Wayne Interchange Plaza II 155 Route 46 West Wayne, NJ 07470 (201) 890-9229 FAX (201) 890-7029 Joseph B. Zichermon, PhD Is PVC Piping iii Firesafe? CTL027233 a ecause polyvinylchloride (PVC) vent system is a more vulnerable plastic is an organic polymer, there are piping system than supply piping because Bfrequent firesafety questions it uses larger pipe sizes, the pipe is empty about its use as piping m fire- most of the time, the system is vented and resistive construction. What includes stacks, and the connections must measures must be taken to ensurepethnetrinate wall membranes at various lo tegrity of fire-resistive assembliecsatpioennse. From a firesafety standpoint, the trated by PVC piping or assemblies contain worst penetrations for DWV piping are ing PVC piping in wall cavities or floor/ back-to-back penetrations for trap con ceiling spaces? What is the firesafety record nections. Single-side trap connections of PVC piping used in plumbing applica and pipe stacks or branches that are tions? within a cavity wall, but have no trap con Answers to these questions lie in a re nections, are less critical. view of testing and research results, per With these parameters in mind, each of formance in the field, and applicable the initial ASTM E-l 19 test series ap codes and standards.1 proached the problem from a different Historical Review perspective. The CFR series, which was the most extensive, assessed the perfor The performance of PVC pipe was orig mance of PVC pipe on a side-by-side basis inally evaluated in extensive ASTM E-119 with cast iron, copper, and acrylonitnle- fire-endurance test programs conducted butadine-styrene (ABS) plastic pipe sys in the early 1970s at the National Institute tems. This series evaluated walls as nar of Standards and Technology's (NIST) row as those based on 2-by-4-inch wood Center for Fire Research (CFR), Ohio framing and as deep as double-stud walls State University, and the University of on wide plates, which are commonly California at Berkeley.2 These programs found as party walls in townhouse-style were designed to determine whether fire- construction. Test configurations also in resistive wall assemblies whose cavities cluded various plumbing chase designs contained plastic drain, waste, and vent and a metal stud wall. (DWV) piping and whose membranes had The CFR tests provided information on been penetrated by fixture connections the base-line performance of the materi could maintain their fire ratings. The test als in various framing and piping config results showed that, depending on how urations. The tests also demonstrated the the pipe was installed, it would not reduce importance of clearance between ele the fire ratings of such walls. ments of PVC piping that penetrate gyp ASTM E-119 was used in these pro sum wallboard and the importance of pre grams because it was the only test method venting stresses on wallboard, especially available to assess uniformly the perfor those that could be caused by fittings at mance of such elements as plastic pipe through-penetrations, oversized pipe, and that entered, exited, or went all the way fitting contact. Installation methods, through--that is, "through-penetrated"-- which included metal sleeving for plastic a test assembly at the time the fire-endur pipes, were also tested. ance performance of assemblies contain The Ohio State tests evaluated rela ing plastic pipe became important to tively standard ASTM E-119 test wall as regulators. However, ASTM E-119 was not semblies without attempting to account a perfect test method. It required a spec for vertical fire spread to simulated upper imen no smaller than 100 square feet, but or lower floors. Grout was used as the it did not provide specifics on instrumen firestopping material where plumbing tation or specimen configuration. Nor traps connected to waste and vent stacks. were there any criteria defining the atmo One- and 2-hour-rated designs of 2-by-4- spheric pressures applied to specimens in inch and 2-by-6-inch wood-frame walls the test furnace. Overlaying this situation, with PVC drain, waste, and vent pipes which itself contributed to variability in were successfully tested for both fire en testing methods, were the large number of durance and hose stream resistance. fire-resistive assemblies the codes ac The University of California series cepted, none of which had ever been tested 1-hour-rated, 2-bv-6-inch wood- tested with piping installations of metal or frame test walls with simulated floors plastic. above and below a fire floor. Two tested These factors, as well as the large num methods were successfully used to fire- ber of plumbing system configurations stop locations where PVC traps pene and combinations possible, made it nec trated gypsum wallboard: Either 16-gauge essary to select and test the most basic sheet metal heat shields were installed to plumbing wall designs available. The de protect the penetration area, or fiberglass signs chosen were based on certain con batt insulation was placed in the piped siderations. Among these was the fact that stud cavity to a height of 48 inches. the most commonly used and most eco These three test series revealed the im nomical plumbing wall is the wood-stud portance of installation methods which cavity wall of minimum depth faced with included the use of grout, metal sleeves, gypsum wallboard. The drain, waste, and heat shields, and thermal insulation. In stallation detailing, which prevented pipe and fittings from pressing against gypsum wallboard membranes, was shown to help performance and to prevent the formation of openings that might lead to premature burn-through. Penetration diameters could not be oversized, and annular spaces had to be sealed with the appro priate materials. Nor could openings in plates be oversized unless they were filled with firestopping materials.' New Tost Method Adopted In 1981, the adoption of ASTM E-814, Fire Test Method for Through-Penetra tion Firestops, provided a needed meth odology for testing items penetrating fireresistive assemblies. It was developed to define instrumentation, appropriate spec imen sizes, and configurations to evaluate through-penetrations of an assembly whose fire rating had been previously es tablished in the full-scale ASTM E-119 for mat. ASTM E-814 uses the ASTM E-119 time-temperature curve, but it allows for smaller specimens, since the test assem bly need only be representative; from a practical standpoint, this means having sufficient clearances between the edge of the specimen, the test furnace, and the firestop itself. This does not preclude us ing ASTM E-814 with large specimens such as those required for ASTM E-119, evaluating multiple penetrations, or as sessing other firesafety aspects of an as sembly while assessing the integrity of the through-penetration. The ASTM E-814 method has proven useful in developing new products be cause it provides a specific test method for regulators concerned with throughpenetration integrity. It has proven espe cially appropriate for evaluating straight through-penetrations, such as those made for sprinkler piping, supply piping, and elements of other mechanical or electrical systems. ASTM E-814 has been adopted by all three US model code organizations and is referenced in the Conference of American Building Officials (CABO) guidelines dealing with ducts, shafts, and pipe and cable penetrations. A similar standard was developed by Underwriters Laboratories as UL-1479. In contrast to generic plumbing ele ments installed in cavity walls, which typ ically are subjected to tests under ASTM E-119 or ASTM E-814 with ASTM E-l 19sized specimens, most of the listed and labeled proprietary penetration firestop ping systems and devices deal with straight through-penetrations of mono lithic assemblies, such as slabs or walls They are not generally applicable to plumbing wall penetrations of gypsum wallboard membranes, though excep tions do exist. While few' technical articles referring to the fire performance of PVC pipe were HBUOURNAL NOVEMBER/DECEMBER 1990 CTL027234 ___ >. .. -. K O tt'.A U N I *1IT1 published in the 1980s, third-party labo ratories and listing agencies conducted numerous ASTM E-119 and ASTM E-814 tests during that period. The outcome of these tests reflects a maturation of indus trial technology and constitutes a sub stantial data base. Table 1 summarizes such fire-endurance test results on PVC pipe products with generic and propri etary firestopping systems, conducted by both public and private testing agencies under the ASTM E-119, ASTM E-814, and UL-1479 test protocols More recently published were the find ings of an independent study conducted over the past several years to evaluate the firesafety of plastic piping products. The study, part of an environmental impact report for the State of California's Depart ment of Housing and Community Devel opment. examined the appropriateness of revising the state plumbing code to allow expanded use of plastic pipe. These find ings indicate that PVC piping products are safe for use in fire-rated buildings, pro vided compartmentation is maintained.1 r' The report recommends appropriate con struction techniques and through-pene tration firestopping methods to achieve this, and stresses effective enforcement of applicable codes and standards. Fir* Endurance el PVC Pipe Once flashover has occurred in a build ing plumbed with PVC pipe, what can be expected to happen? And what have we FI URE 1 Fire-Endurance Testing of PVC Pipe Products: E-814 Test Preparation (Before) PVC piping was tested using ASTM 1-814, Fire Test Merited for ThrowghPenetretien Firesteps. H was Installed in e fire-resistive wall assembly whose fire rating had been previously established in full-scale ASTM E-T19 tests. learned from fire-endurance testing of these products over the past 20 years? The ASTM E-119 test models a conserv ative, post-flashover structural fire. In such a situation, most heat transfer within the space affected by the fire is by radia tion and re-radiation, as opposed to con duction through building elements, or by convection, as through the movement of hot gases.'' From a practical standpoint, PVC pipe found in cavity walls is strongly affected by this balance of heat transfer modes because increased temperatures cause PVC pipe to soften, sag, and even tually fall to the bottom of a stud cavity or plumbing chase well before the gypsum wallboard protecting the cavity falls away. This results in minimal exposure of the pipe to direct thermal radiation. For example, wallboard fall-off does not typically occur in a two-hour ASTM E-119 fire exposure of an assembly that consists of two layers of Vn-inch gypsum wallboard on each side of metal or wood studs. As a result, the cavity heats up far more slowly than the fire compartment because it is shielded by the wallboard. PVC pipe within such a stud cavity will soften, melt, and drop to the bottom of the cavity in the first hour of the test. Rather than being distributed throughout the height of the wall, the pipe is thus found as a charred mass at the bottom of the stud cavity when interior temperatures there begin to approximate furnace tem peratures. This observation has been borne out by examination of hose-stream specimens, whose exposure duration is half the rating of a test wall, where PVC stack materials are found at the bottom of plumbing chases. How does PVC piping in a wall cavity' or passing through a wall affect the fire per formance of the rated assembly? The fire endurance of rated assemblies built with steel or wood framing, gypsum wallboard. and concrete-and-masonry walls, floor slabs, and floors ceilings is well charac terized from a regulatory standpoint. Ex amples of many wall, floor, and floor ceil ing designs that have 1-. 2-, or 3-hour fire ratings are found in the model codes, in UL's Fire Resistance Directory, and in the Fire Resistance Design Manual pub lished by the Gypsum Association. One of the reasons the concept of generic, fire rated assemblies is so widely accepted is that such designs have been tested re peatedly through the years under the ASTM E-119 method in similar, generally accepted configurations. However, an almost unlimited variety of assemblies may exist when plumbing is installed in the field. For example, a wall is the most common type of fire-rated as sembly used with plumbing systems. It may include a simple through-penetra tion, as for sprinkler piping; various con figurations of pipe without penetrations, CTL027235 nHUOURNAl NOVEMBER/DECEMBER 1990 as for runs of drain and vent pipe: or a single penetration, as for a single sink, often called a "membrane penetration." Back-to-back penetrations, such as those that occur in certain fire-rated, multipleunit dwellings and include vertical runs of DWV pipe, are perhaps the most common, most critical configurations from a firesafety standpoint. In principle, a wall assembly penetrated by any material is more prone to failure than the same assembly without penetra tions. This is because openings or disrup tions in protective membranes such as gypsum wallboard cause stress that is ab sent from unpenetrated assemblies. For wall assemblies, the most stressful situa tions include DWV lines running vertically within the wall and through-penetrations, as opposed to membrane penetrations of only one side. For this reason, satisfactory fire test results from wall assemblies with vertical pipe runs and a through-penetra tion provide the "worst case" fire test sce nario. Assemblies in which PVC piping materials run within cavities but do not through-penetrate the wall or penetrate just one side of the wall are less stressed and thus less prone to failure than the designs incorporating both through-pen etrations and vertical runs of PVC drain and vent piping. In the past, concern has been raised about the use of exposed PVC pipe in areas such as parking garages and the basements of fire-resistive buildings. Since such buildings incorporate compartmentation, the boundaries of the fireresistive construction envelope are re quired to prevent fire spread, and they are designed accordingly. If through-penetra tions are properly protected, fire spread from affected compartments is thus mit igated. In addition. PVC pipe will not ig nite readily before flashover because it contains chlorine, which provides built-in resistance to ignition, and does not con tain plasticizers, which would reduce that resistance. After flashover. the exposed PVC piping will contribute to the fire and smoke developed, along with any other combustibles in the affected compart ment. of these methods use non-shrinking grouts or commonly available fiberglass batt insulation to prevent fire spread. The second approach to firestopping PVC through-penetrations of fire-rated walls, slabs, or assemblies involves the use of proprietary firestopping products. Most of these products are specialized mastics, insulations, or thermally acti vated systems based either on mechanical closure of openings or chemical closure achieved through intumescent tech nology.7 These systems rely on the fact that, during a fire exposure, PVC pipe be comes soft before igniting. Thus, an ap propriate intumescent material will close and seal an opening containing such a pipe before fire can spread. Successful 1-, 2-, and 3-hour fire tests have been conducted with intumescent systems for openings in masonry walls up to 12 inches in diameter, under positivepressure fire-test conditions." Tested and listed thermally activated mechanical fire stopping devices include those that can plug a pipe at a through-penetration or cut through a plastic piping assembly and seal it with a guillotine-like device to prevent fire spread when elevated temperatures occur. Recent Research Since the early 1980s. research into PVC piping firesafetv has focused on two areas. The first is proprietary systems for firestopping that require extended fire FIGURE 2 Fire-Endurance Testing of PVC Pipe Products: E-814 Test Results (After) Firestopping Approaches ami Systems for PVC Pipe Firestopping for PVC piping systems falls into two categories. The first involves generic, passive approaches and non-pro prietary materials such as grout, thermal insulation, and other filling or backpack ing materials at penetration locations. These methods have been demonstrated in ASTM E-119 tests on cavity walls with DWV stack and trap connections. This ap proach has been successful for various 1and 2-hour-rated plumbing wall assem blies, provided construction detailing is performed reasonably. The most typical The resells ef the ASTM 1-814 fire endurance test of PVC piping in a fire-resistive mtomhiy are evident in these two photos, taken after the tvit wa cwnpMTNe FltUOURNAt NOVEMBER/DECEMBER 1990 CTL027236 endurance 01 involve larger openings and pipe sizes and larger numbers of pen etrating elements. These efforts have led to the development of specific systems and associated installation methodolo gies to protect such openings, and to list ing with approved third-party agencies. In most cases, the research committee of one or more of the model code organiza tions has also reviewed the performance of these products. The second area of research involves development of generic firestopping sys tems for metal-framed walls similar to those demonstrated in the 1970s for 1and 2-hour-rated wood-frame walls. In a recent test series conducted with generic firestopping based on grout or fiberglass batt insulation, PVC dram, waste, and vent stack systems with through-penetrating l'/>-inch laterals and traps were installed in 1- and 2-hour non-combustible steelstud wall assemblies faced with gypsum wallboard. The tests were conducted un der positive pressure, as called for in the codes for ASTM E-814 testing. Both smalland large-scale assemblies--that is, 4-by- 5-foot and 10-by-12-foot assemblies-- were tested so that correlations between the former, which are most typically used in ASTM E-814 tests, and the latter, re quired for ASTM E-119 testing, could be observed. In the latter, instrumentation of through-penetrations was conducted ac cording to ASTM E-814, and test speci mens included vertical penetration of concrete inserts that simulated slabs at the top and bottom of exposed sections of test walls. Post-test photos of such pen etrations show no vertical fire spread be yond the tested area (see Figure l).,",, These tests confirm that generic fire stopping approaches for PVC pipe per form as satisfactorily with steel-frame as semblies as they did with the wood-stud wall assemblies tested earlier by the CFR, Ohio State University, and the University of California at Berkeley. Pressure Effects el PVC Pipe During a post-flashover fire, there are pressure gradients that increase from neg ative values in the range of -0.02 to -0.01 inches of water at floor level to zero at about one-third the height of the affected room. These pressures continue to in crease so that, near the ceiling, positive pressure may be in the range of + 0.02 to +0.04 inches of water.11 The effect of such pressure gradients on fire travel through assemblies that include penetrations has been debated exten sively in code forums, where the pres sures in test furnaces have been an issue. In response, each model code organiza tion has stipulated that positive pressure be applied to assemblies tested under ASTM E-814. This is a conservative as- The Toxicity Issue One aspect of PVC piping that may affect those who fight whether lethality data from ro dents can be directly extrapolated fires is the toxicity of its products to man because of anatomical dif of combustion. The NFPA's Fire ferences in the respiratory tract of Protection Handbook addresses the rodent and the primate. Inter this point in Chapter 4, "The Char estingly, exposure doses of hydro acteristics and Behavior of Fire." gen chloride that cause post-ex When PVC bums, it produces posure death in rats are in the hydrogen chloride, a potent sen same range as those that have re sory irritant and a strong pulmo sulted in post-exposure deaths of nary irritant. Concentrations as baboons, although the data for ba low as 75 ppm are extremely irri boons are very limited and the tating to the eyes and to the upper comparison is rather subjective. respiratory tract, and impairment The lethal toxic potency of hydro from a behaviorial standpoint may gen chloride with rats is actually also result. Although studies have only somewhat greater than that found that hydrogen chloride gas of carbon monoxide. Consider does not physically incapacitate ation of the exposure dose of car non-human primates subjected to bon monoxide thought to be haz concentrations up to 17,000 ppm ardous to humans would lead one, for 5 minutes, the toxicant has based simply on relative lethal been reported to cause post-ex toxic potencies, to suspect that posure death at doses which did exposure to humans to the range not appear to incapacitate. of 700 ppm or more of hydrogen There is considerable contro chloride for 30 minutes would be versy as to what concentration of highly dangerous. It is prudent to hydrogen chloride is hazardous to realize that hydrogen chloride is man. Although numerous studies dangerous to humans at concen of the acute effects of hydrogen trations well below those indi chloride have been conducted cated by its lethal toxic potency. with rodents, it is questionable sessment, however, since a fire-resistive assembly is most commonly penetrated by a pipe at a sink, which will be under negative pressure during a post-flashover fire Yet such pressure requirements are appropriate in testing, since piping may also pass through fire-resistive assemblies high in a room, as at floor penetrations or above a hung ceiling. Sprinkler piping, for example, is usually run overhead, as is domestic hot and cold water piping.1" Water Distribution Piping Because the cooling effect of the water contained in both chlorinated polyvinyl chloride (CPVC) sprinkler systems and domestic hot and cold water systems pre vents ignition and because the additional chlorine atom on the CPVC molecule en hances its fire performance compared to the usual PVC piping materials, generic firestopping approaches are appropriate for these systems. For openings with a diameter greater than 2 inches, devices and proprietary systems tested with PVC or CPVC in these size ranges should be used as required by the codes. Listings for CPVC-based fire sprinkler systems were obtained after fire tests that included both direct and indirect expo sure of sprinkler piping and fittings to fire conditions. These included ambient ex posures with temperatures up 1,700F from burning wood cribs secondarily fueled with heptane. Various types of sprinklers were evaluated with the CPVC systems, and listings for both light and ordinary occupancies, as well as residen tial use under NFPA 13D, Standard for Sprinkler Systems m One- and TwoFamily Dwellings and Mobile Homes, have been issued.1114 Codas and Standards In the 1980s, the plastic pipe industry increased its efforts to make systematic installation information available to code officials, specifiers, and engineers who used PVC piping products in fire-rated construction. These efforts included pub lication of the installation manual Plastic Pipe in Fire-Resistive Construction.15 A second edition of this document has been prepared and is currently being reviewed by CABO's National Evaluation Service. During this same period, changes in each of the model building codes allowed for performance specification of PVC plastic pipe products in all classes of structures, provided installation method ologies meet stated guidelines.Ib In addi tion, incorporating the ASTM E-814 test standard in the codes has led to a more uniform approach to testing and using PVC piping materials. Fluid Data on Flro PoHoihnihco PVC plastic piping has been used widely in the United States for drains, HMJOURNAL NOVEMBER/DECEMBER 1990 CTL027237 TAAU1 Fire-Enduranc T sting of PVC Pipe Products Construction PVC piping systems tested ASTM E119 and ASTM E8I4 fire ratings achieved Summary of tests conducted Cavity Walls and Partitions Bearing and non-load-bearing gypsum-clad assemblies with wood or steel studs, minimum frame 2- by 4-inch nominal; tests have included plumbing chases to 20 square inches 1'/^-inch laterals with maximum 4-inch vertical DWV pipe, with generic fire-stopping approaches: maximum 6-inch throughpenetrating elements tested with proprietary approaches tested One and two hours Cavity Floors/Ceilings Wood- and metal-framed assemblies with 10-inch nominal joist systems with gypsum wallboard lower membrane and plywood or concrete upper surfaces Maximum throughpenetration size of 4 inches Two hours Solid Concrete Slab Masonry Walk and Floors/Ceilings Thickness ranges from 4 to 8 inches details Maximum opening size tested of 12 inches Two and three hours Twelve using generic firestopping approaches; four using proprietary approaches Two using proprietary fire- Seven using proprietary stopping firestopping* `TheM' are included as examples Substantially greater numbers of assemblies have been tested with proprietary systems than are presented here waste removal, vents, roof drains, chilled water, and low-temperature heating and cooling in non-fire-rated construction for over two decades. The firesafety record for these materials and the fire test results discussed above have been largely re sponsible for their increased use in more restrictive construction applications. In addition, the sections on alternate materials and methods in each of the model codes have permitted installation of PVC dram, waste removal, and vent piping in fire-rated construction for some > ears. Among these are multiple-unit, fireresistive structures, including high-rises. In those projects, no evidence of a firerelated product defect or failure has been reported or been the subject of a product liability action. The latter is a good ba rometer of PVC piping fire performance, given the litigious climate in which we work and live. Rarely have products used in fire-resis tive construction been subjected to as ex tensive evaluation as PVC-based piping products. They have been the subject of fire-endurance testing at both publicly and privately funded laboratories on nu merous occasions and in a variety of con figurations, and this test work has been further evaluated by third parties involved jn the regulatory process at local, state, jgional, and federal levels. The results of its testing and evaluation, as well as many years of field use, indicate that prop erly installed PVC-based piping products do not constitute a fire hazard in structures. FJ Joseph Zicherman is President of IFT Technical Sendees. Inc., in Berkeley. Cal ifornia.1 2 * 4 * * 7 8 1 The specific product* considered here include P\C dram, waste, and vent piping CPVC domestic hot or cold water piping, and CP5C (chlorinated i>olv\invJchloride) sprinkler piping CP\C is deriv ed from PVC None of these products include plasticizing additives They are based on unplasiicized P\ C referred to m Europe as "UPVC " 2 See also NFPA 251. Standard Methods of Fi re Tests of Building Construction and Material* 3. This is consistent with good practice smie over sized openings at plates or other penetration locations for any penetrating elements, plastic or other* ise run counter to building code regulations that are designed to prevent spread of fire and smoke from (ompart- ment to compartment Each of the model codes < on- tains language to this effect 4 SRI (Menlo Park). "Plastic Plumbing Pipe Duift Environmental Impact Report, State of (. alifomia de partment of Housing and Communirv Development. Draft 1. 1983 5. SRI (Menio Park), 'Plastic Plumbing Pipe Draft Ennrrmmental Impact Report State of C aiifomia De partment of Housing and Community Development Draft II. August 1989 i) AM Kanurv andDJ Hohe A Theoiem nl \milg-ts of the ASTM E-1 /9 Stnudunl Fur Test Hiultlmg (-in struction Materials NBS-GCH l s Department of Commerce National Bureau of Standards l(|s^ 7 Intumescent materials are those that are engi neered to expand during a fire and create an insulating char barrier. 8 Underwriters Laboratories Building Materials Di rectory. Underwriters Laboratories. Inc . Northbrook, Illinois. January 1988 9 Waroock Hersey international. Inc, Report on the Fire Endurance and Hose Stream Tests of PVC Plastic Pipe Penetrations Through a 7' -i-Inch-Thick. 1-Hour Rated Gypsumboard and Steel Stud Wall," Fire Per formance ofPVC Pipe in Son-Combustible Construc tion Files WH1-495-PSY-0580 and WHI-49.>PSV*<Ki35 Pittsburg. California January 1989 10 \\ arnock Hersey International Inc "Report on the Fire Endurance and Hose Stream Tests of PVC Plastic Pipe Penetrations Through an S` j-lnch-Thu k 2-Hour Rated Gypsumboard and Steel Stud Wall ' Fire Per formance ofPVCPipe in Son-Combustible Construc tion. Files WHM95-PSV -0560 and WHI-49o-PS\ -0035 Pittsburg. California. January 1989 11 JB Fang. Statu Pres.smes Prod in ed hg Rtnuo Fnes NBSIR 80-1984 National Bureau of Mandards ( enter for Fire Research 12 Interesting^*. in Canada, the building code calls for positive pressure testing to be conducted at a level 10 times that called for in the United States The justi fication for this is. m part based upon 'stack effect' arguments. One can question the requirement for such high pressure differentials at tests based on the pres ence of engineered smoke control pressurization sys tems in high-nse buildings constructed today Such buddings in the United States are also required to incorporate fire-resistive construction and sprinkler systems Com ersely, the suck effect is not a factor in low-rise, fire-resistive buddings 13 RC Wdgmg. "Plastic Fire Sprinkler Piping 19671987," The Building Official and Code Administiator. July August 1988 14 Underwriters Laboratories Inc Report on CPM Pipe and Fittingsfor Sprinkler Systems. File Ex3754 Project 85NK837. Underwriters Laboratories Inc Northbrook. Illinois. July 17 1985 15 Available from the Plastic Pipe and Fittings As sociation. Glen Ellyn. Illinois 16 For example. BOCA Code Sections 401 4 915 71 915 4. 915 41. ICBO Code 4302 4304 4305 1706 (ad ditional changes will appear in the 1991 UBC). and SBCC1 Code Sections 704 9 1. 705 1 4. 1001 3 1 FIMJOURNAL NOVEMBER'DECEMBER 1990 CTL027238