impact of elevated temperature conditions on the

Impact of Elevated Temperature Conditions on the Performance of Firefighting Foams

Chang Jho, Ph.D.

Dynax Corporation, NY

USA

JOIFF FOAM SUMMIT London, February 10, 2020

Reference: Preliminary Investigation Report No: AIFN/0008/2016, issued on 5 September 2016

Emirates FL 521 Crash Fire in Dubai

Emirates FL 521August 3, 2016

Air temperature: 48oCDew Point: 6oC = 8.4% RHAverage Dubai Summer temp: July (42oC): Aug (43oC)

“Full control of the fire was achieved approximately 16 hours after the impact.”

JOIFF Foam Summit London, February 10, 2020

Can any foam be effective under these temperature conditions?


Australian Senate Recommends…

Recommendation to CASA (Civil Aviation Safety Authority): “The test should take place under conditions unique to Australia (such as higher ambient temperatures) to establish whether the foam operates effectively to extinguish aviation fires.”

Australian airport temperature reference: Mike Willson, Should we be trusting small- scale fire tests to provide adequate life safety? The Catalyst, p.5 Q1(2020)

184 days (>40oC) in 2018!!

Temperature Requirements for Approval Fire Tests

Can anyone guarantee the effectiveness of an approved foam when used far outside of these minimum approval temperature conditions?


Air Foam Solution Fuel

UL-162 - - ≥10oC

ICAO ≥15oC ≥15oC -

EN 1568-3 (15 ± 5)oC (17.5 ± 2.5)oC (17.5 ± 2.5)oC

US Mil-spec - (23 ± 5)oC

Temperature RequirementFoam Standard

Temperature Effects on Foam Quality (G. Geyer Study)


Reference: George B, Geyer, Lawrence M. Neri and Charles H. Urban, Comparative Evaluation of Firefighting Foam Agents, FAA Report (FAA-RD-79-61)(1979)

“In general, the temperature of the water and foam liquid was determined to be more influential than the ambient air temperature in establishing the foam quality produced by any particular foam-dispensing system”

6 gpm aspirated nozzle

52oC

2oC

Foam Expansion Ratio

Quarter Drain Time

Temperature Effects on Fire Control Time (G. Geyer Study)


Reference: George B, Geyer, Lawrence M. Neri and Charles H. Urban, Comparative Evaluation of Firefighting Foam Agents, FAA Report (FAA-RD-79-61)(1979)

“…the firefighting effectiveness of AFFF tends to increase as the solution temperature is increased, while proteinaceous agents required a longer time for fire control at the high

solution temperature…” “..The ambient air temperature was of minor importance…”

10x10 ft2/6 gpm nozzle/Jet A

Control Time

52oC

2oC

AFFFs P & FPs

Objectives


To find out how the elevated temperature conditions impact the fire performance of UL- and ICAO-certified grades of commercial Fluorinated* and Fluorine-Free Foams (F3)**

according to the respective approval standard.

*Fluorinated Foams: AFFF & AR-AFFF (Alcohol-Resistant AFFF)**Fluorine-Free Foams(F3): F3 & AR-F3 (Alcohol-Resistant F3)

Fire Test Configurations


UL-162

Type III Level B Level C

Pan 50 ft2 ~4.5 m2 (Circular) (= 50 ft2) ~7.32 m2 (Circular)

Nozzle 2 gpm "Mil-spec" UNI86 UNI86

Nozzle pressure 100 psi 700 kPa 700 kPa

Flow rate 2 Gallon/min 11.4 L/min 11.4 L/min

Application rate 0.04 gpm/ft2 2.5 L/min/m2 (=0.061 gpm/ft2 ) 1.56 L/min/m2 (= 0.038 gpm/ft2)

Nozzle position Fixed until control Fixed Fixed

Fuel Heptane Jet A1 Jet A1

Preburn 1 min 1 min 1 min

Total foam application 3 min 2 min 2 min

Extinction time ≤ 3 min ≤ 1 min (2 min)* ≤ 1 min (2 min)*

Burn Back ≥ 5 min (20%) ≥ 5 min (25%) ≥ 5 min (25%)

*Since 2014 small rim fires are allowed up to 2 min.

ICAO Test Configuraion

Fire Test Conditions and Test Products


# Tests

Temperature (oC): Low High Diff. Low High Diff. Low High Diff.

Air 28 ± 1 40 ± 1 12 28 ± 1 40 ± 1 12 28 ± 2 39 ± 3 11

Foam Solution 27 ± 1 35 ± 2 8 27 ± 1 36 ± 2 9 31 ± 5 36 ± 0 5

Fuel 26 ± 2 36 ± 4 10 27 ± 2 41 ± 6 14 27 ± 3 37 ± 3 10

Test Location

Water used Freshwater

*Commercial

8

Level B

5 3

Level C

ICAO

UL (8): 2 AFFF(3%)/2 AR-AFFF(3x6); 1 F3(3%)/3 AR-F3(3x6)

Test Condition

Test Products*

UL-162

ICAO Level B (5): 1 AFFF(3%)/2 F3(3%)/1 F3(6%)

ICAO Level C (3): 1 AFFF(3%)/1 F3(3%)/1 AR-F3(3x6)

Outdoors

Fire Test Results: Low vs. High Temperature Comparison(Foam Expansion Ratio: Combined Data)


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Fluorine-Free Foam (F3) (AR)-AFFF

Fire Test Results: Low vs. High Temperature Comparison(Quarter Drain Time: Combined Data)


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(AR)-AFFFFluorine-Free Foams (F3)

>60 min

Fire Test Results: Low vs. High Temperature Comparison(90% Control Time: Combined Data)


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(AR)-AFFFFluorine-Free Foams (F3)

Fire Test Results: Low vs. High Temperature Comparison(Extinguishment Time: UL)


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No EXT

Fire Test Results: Low vs. High Temperature Comparison(Extinguishment Time: ICAO)


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Fluorine-Free Foam (F3) AFFF

Spec ≤ 2 min

Summary of Fire Test Results: Low vs High Temperature Comparison (UL-162)


Key Observations:▪ On all foams, FXR slightly increased with temperature, while QDT is markedly decreased. ▪ CT(90%) decreased on all F3s (improved performance): 2 AR-AFFFs showed the same trend.▪ All fluorinated foams and all but one F3 foams passed the XT at both temperatures.▪ AR-AFFFs performed the best, passing all tests at both temperatures, followed by AFFFs. ▪ All F3s but one failed the BB at both temperatures, which passed at low temperature failed

at high temperature

FXR/Foam Expansion Ratio: QDT/Quarter Drain Time: CT(90%)/90% Control Time: EXT/Extinguishment Time: BB/Burnback

FXR QDT CT (90%) BB

7-8 2-3 min < 1 min 1-3 min

Fluorinated Foams

AR-AFFF(3x6)-UL1 0.4 -0:41 -0:14 -0:06 Pass/Pass Pass/Pass

AR-AFFF(3x6)-UL2 0.2 -1:38 -0:06 0:07 Pass/Pass Pass/Pass

AFFF(3%)-UL1 0 -0:24 0:15 0:31 Pass/Pass Pass/Fail

AFFF(3%)-UL2 0.2 -0:16 0:10 0:45 Pass/Pass Pass/Fail

F3 Foams

AR-F3(3x6)-UL1 0.5 -0:32 -0:09 0:02 Pass/Pass Fail/Fail

AR-F3(3x6)-UL2 0.2 -1:40 -0:02 None/2:40 Fail/Pass Fail/Fail

AR-F3(3x3)-UL3 -0.4 - -0:25 -0:28 Pass/Pass Pass/Fail

F3(3%)-UL1 -0.2 -1:32 -0:07 -0:27 Pass/Pass Fail/Fail

Trend Increase Decrease Decrease -

EXTTest Product

Low/High Low/HighDifference: (Low → High) Temperature

Summary of Fire Test Results: Low vs. High Temperature Comparison(ICAO Level B & C)


Key Observations:▪ On all foams, FXR slightly increased with temperature, but QDT is markedly decreased. ▪ CT(90%) decreased on all F3s (improved performance).▪ None of the F3s passed the XT despite excellent CT(90%) at high temperature, all within 1 min. ▪ Both AFFFs passed the XT at high temperature. One that failed at low temperature passed at high temperature.

FXR/Foam Expansion Ratio: QDT/Quarter Drain Time: CT(90%)/90% Control Time: EXT/Extinguishment Time: BB/Burnback

FXR QDT CT

6-8 2-3 min < 1 min 1-2 min Low/High 10-15 min

Fluorinated Foams

AFFF(3%)-ICAO1 B -0.2 -0:22 0:06 0:04 Pass/Pass -5:13 Pass/Pass

AFFF(3%)-ICAO2 C 0.5 -0:31 -0:04 None/1:16 Fail/Pass +2:00 Pass*/Pass

F3 Foams

AR-F3(3x6)-ICAO1 C 0.1 -1:41 -0:01 None/None Fail/Fail - -

F3(3%)-ICAO1 B 0.3 -0:39 -0:06 None/None Fail/Fail - -

F3(3%)-ICAO2 B 0.4 -2:00 -0:14 None/None Fail/Fail - -

F3(3%)-ICAO3 C 0 -3:04 -0:10 None/None Fail/Fail - -

F3(3%)-ICAO4 B - - -0:31 None/None Fail/Fail

F3(6%)-ICAO5 B -0.2 +0:13 -0:06 None/None Fail/Fail - -

Trend Increase Decrease Decrease -

EXT BBTest Product

ICAO LevelLow/High

Difference: (Low → High) Temperature

*A small rim fl icker was put out with small amount of foam to test the BB.


What We Found OutConclusions

UL-162 Tests on UL-certified Foams:

❖ All four Fluorinated foams passed the tests at Low temperature conditions: The two AR-AFFFs performed the best, passing all the tests at both temperature conditions, while two AFFFs failed only the BB at High temperature conditions.

❖ All Fluorine-Free foams failed the tests at both temperature conditions, with the exception of one AR-F3(3x3) which failed only the BB at High temperature conditions.

ICAO Level B & C Tests on ICAO-certified Foams:

❖ All Fluorinated foams passed the tests at High temperature conditions.

❖ All Fluorine-Free Foams (F3) failed the tests at both the Low and High temperature conditions

Low Temperature Conditions: 26-31oC : High Temperature Conditions: 35-40oC


Why?

So, how do you explain the failed BB performance (UL) and failed extinguishment (ICAO) of Fluorine-Free Foams (F3) even at Low temperature conditions, while all fluorinated foams show acceptable performance even at High temperature conditions?

How about the fuel-specific and fuel-sensitiveperformance of Fluorine-Free Foams? (to be discussed later)

Fatal Attraction!!


Hydrocarbon surfactants are inherently oleophilic and attract hydrocarbon fuels

Fluorosurfactants are inherently oleophobic and repel

hydrocarbon fuels

Heptane

Repel!Attract!

Heptane

Fuel pickup & contamination issues →Flashovers, Poor Burnback

Fuel repellency (“chemical vapor barrier”), Fuel shedding effects

Sealability Test based on DEF (AUST) 5706 (2003)*

Fuel-vapor Sealability Comparison: AFFF vs F3 Foams

Reference: Bogdan Z. Dlugogorski, Ted H. Schaefer and Eric M. Kennedy, “Performance of Replacements for Fluorine-containing AFFF,” 3rd Reebok Foam Seminar (2007) & Fire Technology, 44(3), 297-309 (2008)

Conclusion: “…best-performing FfreeF formulation (RF6) provided about 30% of the durability of an AFFF for protection against evaporation of low-flashpoint flammable liquids.”

*Foam Sealability Test (Annex A):Pan: 59.5 cm dia/10.2 cm depth w/conical bottom Fuel: Avgas


References: Katherine M. Hinnant, Michael W. Conroy, Ramagopal Ananth, “Influence of fuel on foam degradation for fluorinated and fluorine-free foams,” Colloids and Surfaces A: Physicochem. Eng. Aspects 522 (2017) 1-17Katherine M. Hinnant, Spencer L. Giles, Ramagopal Ananth, “Measuring fuel transport through fluorocarbon and fluorine-free firefighting foams.” Fire Safety Journal 91 (2017) 653-661

Foam Degradation & Fuel Vapor Barrier Effects: AFFF vs. F3 Foams


n-Heptane vapor transport time through 4 cm thick foam @20oC): F3 (RF6) vs AFFF using FTIR as detector

Fig. 23. Foam degradation versus time for AFFF and RF6 foam at two bubble diametersover heated n-heptane. Initial foam thickness was 1.8–2 cm. 170–210 m and10–20 m spargers were used to generate bubbles. “BD” in the legend refers to thebubble diameter of the foam and “ER” refers to the expansion ratio of the foam.

Foam degradation time on 50oC n-Heptane: F3 (RF6) vs AFFF

Observations:. Fluorine–free foam (RF6) degrades much faster than AFFF, when exposed to 50oC n-Heptane.. The break out rate of n-Heptane vapor is much higher through RF6 than AFFF.. RF6 degradation time scale may be relevant to extinguishment time scales (1-2 min) in fire tests.

Fuel-specific and Fuel-sensitive Performance of F3 Foams


Reference: Gerard G. Back and John Farley, Evaluation of the fire protection effectiveness of fluorine free firefighting foams, NFPA Research Foundation Report, January 2020

= Foam volume/ft2 required to extinguish the fire

AR-AFFF, actually

“The baseline (C6) AR-AFFF demonstrated consistent capabilities against all hydrocarbon test fuels…”with “superior firefighting capabilities through the entire test program under all test conditions.”

But,fluorine-free foams (F3) required: . 3-4 times more foam volume on MILSPEC gasoline (“Mogas”). 6-7 times more foam volume on E10 gasoline

The fuel vapor seal-ability was measured by the time taken to ignition and sustained burning of the foam blanket. (Test is terminated after 30 minutes.)

Test Setup:Diameter of dish (id): 10.5 cm Depth of dish: 3.9 cmFuel volume/height: 40 ml/0.6 cmFoam volume/height: ~220 ml/3.3 cmTest temperature: 25o & 45oC (fuel & foam solution temp.)Test Fuels: n-Heptane, E10 Gasoline (87 Octane)

& Ethanol-free Gasoline (91 Octane)

Test Products*: Fluorinated Foams: 5 AFFFs and 4 AR-AFFFs Fluorine-Free Foams(F3): 5 F3s and 4 AR-F3s*All purchased from market

Lab Fuel Vapor Sealability Test of Foam


1” gas flame

40 mL test fuel

220 mL Foam


Temperature Effects on Fuel Vapor Sealability(E10 Gasoline: 87 Octane)

*Fuel and Foam Solution temperatures @25oC vs 45oC

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Fluorine-Free Foams (F3)(AR)-AFFF


Take Home Messages

The results of this study strongly indicate:Fluorine-Free Foams (F3) may NOT be able to provide acceptable firefighting performance at elevated temperature conditions. This challenges the adequacy of the temperature requirements in the current foam approval standards, especially for F3 foams.

The negative temperature effects on F3 foams are compounded to a greater detriment by their fuel-sensitive and fuel-specific performance.

This does not apply to fluorinated foams!


Take Home Messages (continued)

This study also demonstrates the superiority of C6 fluorinated foams and supports established safety factors. This however is a concern with F3 foams.

More research, especially on large scale fires, is need.

JOIFF FOAM SUMMIT London, February 10, 2020

Contact Info:

Chang Jho, 79 Westchester Avenue, PO Box 285, Pound Ridge, NY 10576 USA

Tel: 914 764-0202 Fax: 914 -764-0533 e-mail: [email protected]

Thank you!

impact of elevated temperature conditions on the

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