Document 8261Gmo6dj2n9wkze6K2wBX6k
PERFORMANCE CHALLENGES OF FLUORO FREE FOAMS
Ted H. Schaefer 3M Australia Pty Ltd Specialty Materials Laboratory
Bogdan Z. Dlugogorski and Eric M. Kennedy Process Safety and Environment Protection Group
School of Engineering The University of Newcastle
AUSTRALIA
3M and fire fighting foams
Forty years ago, seminars were being held to discuss new 3M fluorosurfactant technology and the newly derived AFFF
fire fighting foams.
3MTMLIGHT WATERTM AFFF
1960's developed from fluorochemical surfactants, joint research with 3M and US Naval Research Laboratories-Aqueous Film Forming Foam (AFFF)
Low surface tension of FC allowed water to float on liquid fuel--film formation
Fast fire knock down, fast extinguishment
3M Direction by 2000
Discontinue PFOS based AFFF products through 2003
Types of Foams (Mechanical Foam Generation)
Protein based
- Protein Foam - Fluoro Protein Foam - FFFP - FFFP/AR
Synthetic based
- Class A wildland - High Expansion - Medium Expansion - AFFF - AFFF/AR - Training Foam
How Foams Work
Various Foams can work by:
Excluding oxygen, smothering flames Cool surfaces with water from foam Prevent release of vapours from fuel surface
Class B Foams
Protein Based
* Synthetic based (AFFF)
- Thick foam
- Thinner foam
- Slower moving
- Fast moving
- High yield stress
- Low yield stress
Poor foam re-flow
Good foam re-flow
- Mono dispersed bubble - Poly dispersed bubble size size
Benefits of AFFF
Rapid fire knockdown
Spill and tank fires Long shelf life
* Secure spills Dry Chem compatible Use conventional nozzles Self-healing
Benefit of Fluorosurfactants
Low surface tension ~ 16 mN/m Formation of aqueous film from bubble drainage Spreads rapidly on fuel - initial spreading coefficient High temperature resistance to flame front
hydrocarbon
A new category of fire fighting foams
is emerging.
Types of Foams (Mechanical Foam Generation)
Protein based
- Protein Foam - Fluoro Protein Foam - FFFP - FFFP/AR
Synthetic based
- Class A wildland - High Expansion - Medium Expansion - AFFF - AFFF/AR - Training Foam - Fluoro Free Foams (new)
Foams without Fluorosurfactants
What challenges would need to be overcome?
Fluoro-Free Foams
Existing foams that are fluorosurfactant free have limited effectiveness on Class B fuels
Class B foam companies now doing research for effective non-FC foams
Need to achieve drop in capability
Fluorine Free Foams
Fluorine Free Foam implies no fluorine, in either organic or inorganic form
3MTMRF3 fluorine content measured
- 0.00 % by 3M Australia Lab (NATA)
Compared against distilled water blank
- <0.02 % by LASTFIRE Report 2003
Assuming this is the limit of test method
Key foam characteristics
no longer have aqueous film technology long drain time, to keep foam on fuel good heat resistance free flowing like AFFF self repairing of punctures re-healing for burn back resistance
No fluorosurfactants, No aqueous film formation.
No aqueous film? How can it work?
Bubble structure must compensate - Foam is a series of aqueous films separated by air
Longer drain time foam Should have good heat resistance
-A ch ieve burn back resistance like AFFF/FFFP
NFPA 412 Foam Expansion & Drainage
Foam Expansion
Ratio
25% Drain Time
3MTM AFFF
9:1
6:20
3MTM RF6 (Fluoro Free)
9:1
14:20
Foam Drainage
Grad.Cyl.#1 AFFF Grad.Cyl.#2 AFFF Grad.Cyl.#1 RF6 - b -- Grad.Cyl.#2 RF6
Time (minutes)
Note the slower fluid drainage for RF6
Foam Height
e-- Grad.Cyl.#1 AFFF Grad.Cyl.#2 AFFF Grad.Cyl.#1 RF6 Grad.Cyl.#2 RF6
Time (minutes)
Note the more linear relationship for RF6
Free Flowing Foam
A result of being a low yield stress foam -Compromise foam rigidity for flow
Achieved through a foam structure with poly dispersed bubble sizes -M any sizes of bubbles promote foam flow
Allows foam movement for self repair Achieve extinguishment times like AFFF
Bubble Size Dispersion
Gardiner et al (2000)
Low Yield Stress Foam Flows Around Obstacles
3MTM RF6 demo at Queensland Fire & Rescue Service Training Academy
AFFF Foam Theory
Spreading Of An Aqueous Film
Low surface tension ~ 16 mN/m Formation of aqueous film from bubble drainage Spreads rapidly on fuel - initial spreading
coefficient
hydrocarbon
What Makes Up a Spreading Coefficient?
Air / Foam Solution Interface Air / Fuel Interface Fuel / Foam Solution Interface
Spreading Coefficient (S ) of an Aqueous Phase Over Fuel
S = Yf - (Ya + Y )
Y a= surface tension of aqueous phase Y f = surface tension of fuel Y = interfacial tension
Foam Spreading Coefficient
On Cyclohexane
(as reported by the Univ. of Newcastle, Australia, using static method)
Surface Tension of Cyclohexane
Foam Solution Surface Tension
Foam Interfacial Tension with Cyclohexane
Spreading Coefficient
3MTM 1% AFFF
24.0
16.4
4.3
3.3
3MTM 6% AFFF
24.0
16.2
4.7
3.1
3MTMATCTM@ 3%
24.0
16.2
3.2
4.6
6% AFFF
24.0 17.9
1.4 4.7
AFFF/AR @ 3%
24.0
18.6
2.0
3.4
Fluoro Free Foam @1%
3MTM RF6 @ 6%
24.0 24.0
24.0 26.4
0.6 - 0.6 2.4 - 4.8
Foam Spreading Coefficient
On Cyclohexane
(as reported by the Univ. of Newcastle, Australia, using static method)
Surface Tension of Cyclohexane
Foam Solution Surface Tension
Foam Interfacial Tension with Cyclohexane
Spreading Coefficient
3MTM 1% AFFF
24.0
16.4
4.3
3.3
3MTM 6% AFFF
24.0
16.2
4.7
3.1
3MTMATCTM@ 3%
24.0
16.2
3.2
4.6
6% AFFF
24.0 17.9
1.4 4.7
AFFF/AR @ 3%
24.0
18.6
2.0
3.4
Fluoro Free Foam @1%
3MTM RF6 @ 6%
24.0 24.0
24.0 26.4
0.6 - 0.6 2.4 - 4.8
Foam Spreading Coefficient
On Cyclohexane
(as reported by the Univ. of Newcastle, Australia, using static method)
Surface Tension of Cyclohexane
Foam Solution Surface Tension
Foam Interfacial Tension with Cyclohexane
Spreading Coefficient
3MTM 1% AFFF
24.0
16.4
4.3
3.3
3MTM 6% AFFF
24.0
16.2
4.7
3.1
3MTMATCTM@ 3%
24.0
16.2
3.2
4.6
6% AFFF
24.0 17.9
1.4 4.7
AFFF/AR @ 3%
24.0
18.6
2.0
3.4
Fluoro Free Foam @1%
3MTM RF6 @ 6%
24.0 24.0
24.0 26.4
0.6 - 0.6 2.4 - 4.8
Spreading Coefficient
From the data, fluoro free foams have: -higher surface tensions - a negative spreading coefficient
Therefore, fluoro free foams do not form an aqueous film.
Fire Performance
Does the lack of ability to form an aqueous film effect
fire performance?
ICAO Level B Fire Test
Fluorosurfactant Technology Solution Strength 90% Control Extinguishment Burn Back Time
ICAO Level B
Spec
3 or 6%) -
<60 s > 5:00
3 M im Foam RF6
No Fluoro surfactant
6 30 s 46 s > 8:00*
3M iM FC3003 PFOS
6 50 s 7:06
3 M iM FC206CF PFOS
Arctic FoamTM
203** Telom er
6 38 s 46 s > 8:00*
3 26 s 44 s > 8:00*
Note: * No indication of re-ignition or burn back of foam was observed after 8:00
Trade mark of Solberg Scandinavian AS, published with permission
Comments on ICAO Fire Test
Application density was 2.53 lpm/m2 ICAO has two levels of performance
- A - protein or fluoroprotein foam (small pan) - B - AFFF or FFFP foam (large pan) No discernable difference between AFFF and RF6 on: - Extinguishment - Burn back
0.28 m2 Fire Test
Test method found in the Australian Defence Force specification Def(Aust)5706
Similar to UK MOD specification method, but lower foam flow and lower application time
0.28 m2 Fire Test
0.28 m2 Fire Tests
with Potable Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Potable
Potable
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 (6%)
29 52 12:30 25 50 13:36
FFF #1
35
68 3:30 40
110 5:48
(0.4%)
FFF #2 (2%)
29 122 5:06 26
69 5:12
FC-206CF (6%)
27
42 12:12 24
40 21:18
0.28 m2 Fire Tests
with Potable Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Potable
Potable
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 (6%)
29 52 12:30 25 50 13:36
FFF #1
35
68 3:30 40
110 5:48
(0.4%)
FFF #2 (2%)
29 122 5:06 26
69 5:12
FC-206CF AFFF (6%)
27
42 12:12 24
40 21:18
0.28 m2 Fire Tests
with Potable Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Potable
Potable
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 (6%)
29 52 12:30 25 50 13:36
FFF #1
35
68 3:30 40
110 5:48
(0.4%)
FFF #2 (2%)
29 122 5:06 26
69 5:12
FC-206CF AFFF (6%)
27
42 12:12 24
40 21:18
0.28 m2 Fire Tests
with Potable Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Potable
Potable
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 (6%)
29 52 12:30 25 50 13:36
FFF #1
35
68 3:30 40
110 5:48
(0.4%)
FFF #2 (2%)
29 122 5:06 26
69 5:12
FC-206CF AFFF (6%)
27
42 12:12 24
40 21:18
0.28 m2 Fire Tests
with Potable Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Potable
Potable
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 (6%)
29 52 12:30 25 50 13:36
FFF #1
35
68 3:30 40
110 5:48
(0.4%)
FFF #2 (2%)
29 122 5:06 26
69 5:12
FC-206CF AFFF (6%)
27
42 12:12 24
40 21:18
0.28 m2 Fire Tests
with Synthetic Sea Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Sea Water
Sea Water
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 27 50 11:36 25 52 11:00 (6%)
FFF #1 31 69 4:48 27 67 5:42 (0.4%)
FFF #2 (2%)
32
No Ext No Result
27
120 <1:00
FC-206CF (6%)
31
40 13:30 26
38 14:30
0.28 m2 Fire Tests
with Synthetic Sea Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Sea Water
Sea Water
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 27 50 11:36 25 52 11:00 (6%)
FFF #1 31 69 4:48 27 67 5:42 (0.4%)
FFF #2 (2%)
32
No Ext No Result
27
120 <1:00
FC-206CF (6%)
31
40 13:30 26
38 14:30
0.28 m2 Fire Tests
with Synthetic Sea Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Sea Water
Sea Water
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 27 50 11:36 25 52 11:00 (6%)
FFF #1 31 69 4:48 27 67 5:42 (0.4%)
FFF #2 (2%)
32
No Ext No Result
27
120 <1:00
FC-206CF (6%)
31
40 13:30 26
38 14:30
0.28 m2 Fire Tests
with Synthetic Sea Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Sea Water
Sea Water
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 27 50 11:36 25 52 11:00 (6%)
FFF #1 31 69 4:48 27 67 5:42 (0.4%)
FFF #2 (2%)
32
No Ext No Result
27
120 <1:00
FC-206CF (6%)
31
40 13:30 26
38 14:30
0.28 m2 Fire Tests
with Synthetic Sea Water
(as reported by the Univ. of Newcastle, Australia)
Fuel AVGAS
AVTUR
Water Type
Sea Water
Sea Water
Test
75% Cont. Ext 33% Burn 75% Cont. Ext 33% Burn
Criteria
(s)
(s) Back (min) (s)
(s) Back (min)
RF6 27 50 11:36 25 52 11:00 (6%)
FFF #1 31 69 4:48 27 67 5:42 (0.4%)
FFF#2 (2%)
32
No Ext No Result
27
120 <1:00
FC-206CF (6%)
31
40 13:30 26
38 14:30
Comments on 0.28 m2 Fire Test
Application density was 2.42 lpm/m2 NFPA 11 recommends 4.1 lpm/m2with hand line Discernable differences between the three fluoro
free foams on:
- Extinguishment - Burn back - Sea water compatibility
Fluoro free foams are not all equal in performance
Evaluation Program by US Navy NAVFAC / NRL
Evaluation initiated in 2002 by NAVFAC on "environmentally benign AFFF" products
Testing of 3MTMRF6 on 28 ft2fire (gasoline)
- 50 s extinguishment (spec limit 30 s max) - 7:55 burn back (spec limit 5:00 min)
Failed film formation Operator familiarity with the product will
improve results (39 s)
Comparison of 3MTMRF6 Fire Test Results
Spec
ICAO Level B Australian Defence US Mil (28 ft2)
Exting. (s) 46
52
App Density (LPM/m 2) 2.53
2.42
Fuel
Aviation Kerosene AVGAS
50 2.91 Unleaded (0.07 gpm/ft2) Gasoline
Comparison of 3MTMRF6 Fire Test Results
Spec
ICAO Level B Australian Defence US Mil (28 ft2)
Exting. (s) 46
52
App Density (LPM/m 2) 2.53
2.42
Fuel
Aviation Kerosene AVGAS
50 2.91 Unleaded (0.07 gpm/ft2) Gasoline
Fire Test Result
Is film formation necessary for AFFF like fire performance?
NO!
Achieved near AFFF performance with 3MTM RF foam technology
Challenges for Fluoro Free Foams
In conclusion...
Rapid fire extinguishment - like AFFF Good burn back resistance - like AFFF/FFFP Capable of good vapour suppression Free flowing foam - to support above points Achieve drop in capability Sea water compatible Responsible environmental profile
- Customer decision process
Thank You!