Aspects of Foam Need Careful Consideration – Part 1
There is much discussion about which options are best for future decision-making for Class B firefighting foam applications. It needs careful consideration before making such decisions to ensure the foams chosen will provide the required levels of not only environmental performance, but also firefighting performance and life safety. It’s a complex issue so we are covering it in two parts with this part 1 article now and part 2 following in the next issue.
To achieve a balanced and workable approach requires a more holistic view than a simplistic “one size fits all” stance with mis-categorisation and fearful focus on PFOS and its unacceptable environmental behaviour, resulting in mis-representative and unbalanced views, as has been happening in some areas. Short chain C6 fluortelomer surfactants behave very differently from PFOS, with acceptable environmental performance, along with the required effectiveness and life safety requirements necessary to avoid detrimental decision-making and objectionable outcomes in the longer term. Read on to find more clarity to inform your own answer in this complex area.
PFOS should be a legacy issue
PFOS (PerfluoroOctanyl Sulfonate) and PFHxS (PerFluoroHexane Sulfonate) as most already know are significant breakdown products derived from the Electrochemical Fluorination Process by 3M, which ceased production by 2002 outside China, so should be a legacy issue. PFOS is confirmed Persistent, Bioaccumulative and Toxic. It has long range mobility, is harmful to humans being proven carcinogenic, transfers to the foetus and is found in human breast milk. It also causes harm to our environment, and is listed under the Stockholm Convention as a Persistent Organic Pollutant, or POP.
PFOS is banned from use across the EU1 and Canada2, and little used elsewhere, except China where it is still produced. The disposal recommendation is high temperature incineration because of its POP profile, but although generally no longer available PFOS & PFHxS still reside in some fixed foam and pre-engineered systems ready for discharge, should fire strike.
There could be penalties for discharging PFOS to the environment or waste water treatment systems in some jurisdictions, as occurred following the 2005 Buncefield fire in UK when £1.35m4 of the total £9.5m fines and costs were attributed to environmental pollution, so it is well worth transferring any existing systems containing PFOS based foams into different containers, thoroughly cleaning out the systems and holding the residues, before determining the most suitable remediation treatment for safe disposal. PFOS should now be a legacy issue, but we still need to manage it. Most regulators advise foam users to avoid using PFOS based agents.
Many have done this already, replacing PFOS-based foams with either C6 fluorotelomer surfactant based foams, or completely Fluorine Free Foam (F3). But which foam type delivers the best long term solution to meet increasingly stringent environmental requirements, while also providing effective and efficient firefighting capabilities? This is a more complex Question than many imagine, but these two articles will shed light on that dilemma, to help make your decision-making clearer and perhaps a little easier.
Some foam users are misleadingly told that “all fluorochemicals can behave like PFOS” to encourage a shift to F3, which is far from the truth. This approach mis-represents the alternative telomer-based fluorochemicals, particularly the high purity, short-chain C6 fluorotelomer surfactants, which are not bioaccumulative, have low toxicity, behave very differently from PFOS and have acceptable environmental profiles3.
How are C6 Fluorotelomer foams different?
The fluorotelomer process does not use PFOS as an ingredient, and does not produce PFOS as a breakdown product. Trace amounts of PFOA (PerfluoroOctanoic Acid) are unintentionally formed in the production process, but manufacturers voluntarily agreed to the US EPA’s PFOA Stewardship Program in 2006, with the goal of reducing PFOA from their waste streams, production processes and finished products by 95% in 2010, which has been achieved5. They are now working towards eliminating PFOA and its precursors by end 2015 to such a level that can meet the latest European Chemicals Agency proposed restriction levels for PFOA in firefighting foams6.
Longer chain fluorotelomer surfactant-based (≥C8) foams containing small amounts of PFOA have been already undergoing transition to short-chain predominantly C6 fluorotelomer-based alternatives. The EPA program spawned a broader focus on creating these more environmentally benign foams7,8 using short chain, predominantly six carbon or C6 fluorotelomer surfactants, which behave very differently in the environment and humans from PFOS and PFOA. These high purity 99.5% C6 fluorotelomer surfactant-based foams are now available, that can comply with the latest European Chemicals Agency PFOA acceptability limits6 of 1,000ppb (parts per billion, when 1ppm = 0.0001%) for PFOA and each of its precursors, which allows foams containing these C6 fluorotelomer surfactants as alternatives to those known as “PFOS foams” and “PFOA foams”.
The differences between PFOS and C6 are confirmed by extensive scientific research. This shows C6 fluorotelomer surfactants exhibit low toxicity to aquatic organisms and mammals like us13. They are not bioaccumulative, nor biopersistent, nor biomagnifying8-10. Further studies have shown they are not mutagenic, nor carcinogenic, nor developmental nor reproductive toxicants11,12, and have not been shown to be harmful to human health13. They seem to have a low risk of long range transport binding to sediments14, and a recent risk assessment showed they cannot qualify for POP listing14, as 3 out of the 4 key criteria required for POP listing, are simply not met.
C6 fluorotelomer surfactants are still persistent, but so is concrete, yet this C6 persistence is not shown to be harmful to either humans or the receiving environment 7–14.
Why is foam so beneficial?
Lets go back a step… why do we need foam anyway? Wouldn’t it be better if we could just use water?
Water is heavier than most hydrocarbon and polar solvent flammable liquids. It sinks through the fuel layer and rapidly spreads the flaming fuel into other areas, quickly escalating the fire.
Foam is lighter than water and floats on the fuel surface, providing a suppressing foam blanket to minimise fire spread, provide swift control and cool the fuel. It also protects casualties and firefighters from flames, helps minimise the risk of re-ignition, protects property and investments, minimises business interruption and financial loss, while also minimising environmental impacts and press attention by controlling the incident quickly! But care needs to be taken…
as not all foams behave the same.
Fluorotelomer surfactants are necessary
To achieve all this… C6 fluorotelomer surfactants have been effectively used in AFFF foams for the past 40 years. They provide a critical fuel shedding function15. This prevents the foam from picking up fuel into the bubbles when it is forcefully applied to the fire, as occurs in most practical firefighting incidents15, like the 9m diameter storage tank test in Rotterdam16 and the 2001 Orion 82m diameter tank fire in USA17. It also provides a vapour seal on hydrocarbon fuels, faster knockdown of the fire, often with lower application rates, so there is less smoke, less run-off and less pollution by minimising the foam and water resources needed.
These fluorotelomer surfactants also reduce the risk to life safety from sudden flashbacks and re-involvement15, which can occur when these vital ingredients are missing, particularly on volatile hydrocarbons, such as gasoline.
Consequently they deliver reduced environmental impacts of low aquatic toxicity, their persistence has not shown to be harmful , they are not bioaccumulative, and produce less firewater run-off which could contribute to pollution.
Are there acceptable alternatives?
The main alternative to fluorinated foams is Fluorine Free Foam (F3) and some support these products as the most environmentally acceptable answer, yet there seems to be no fate and behaviour studies. Small qualifying fire tests often show good results, but there seems to be no evidence where major fires have been successfully extinguished by F3 products, it always seems to be fluorinated foams – why is this?
Research has also shown that even “the best performing F3 formulation provides only about 30% of the durability of an AFFF for protection against evaporation of low-flashpoint flammable liquids (like gasoline)18.” So 3 times more F3 is likely to be needed to provide equivalent vapour sealing on volatile fuels, particularly when applied forcefully from standard foam branchpipes or water nozzles, when compared to fluorotelomer based foams like AFFF as Jho’s 2012 research shows15.
This was underlined by a 2013 Caltex incident19 where a F3 foam blanket lasted only 15-20 minutes before requiring top-up on a pressurised unleaded gasoline leak from the base of a bulk storage tank. Considered unacceptable, subsequent use of a Fluoroprotein foam lasted 90 minutes between top ups, 5 times longer, which was considered excellent and allowed the incident to be brought under control.
Large scale test fires involving polar solvent fuels like Ethanol are likely to deliver at least twice the heat exposure of gasoline within a 30-40m radius20, and Alcohol Resistant foams require gentle application to be effective. F3 agents struggle with extinguishing even small test fires of industrial alcohols like IPA21 or Ethanol, so large tank fire scenarios may be uncontrollable, when semi-forceful foam application is almost inevitable.
Consequently it is increasingly being suggested each drum of these F3s should exhibit a warning label confirming it should not to be applied forcefully onto fires involving volatile fuels like Gasoline, to protect the safety of firefighters, as many seem unaware of the inherent dangers. This is particularly relevant to large areas of in-depth fuel in bunded areas, bulk storage tanks, transporting vehicles and ship tankers, and should be an important consideration when selecting future foam concentrates. Might a potential warning label look something like this perhaps?
Independent fire tests conducted in Denmark 2012 showed that all five F3 foams tested failed to extinguish ICAO level B fire tests on Jet A1 fuel with the regular UNI86 test nozzle21, when 3 were certified to pass, suggesting variability. Even poorer performance occurred, through a more realistic modified nozzle21 that better represented foam quality likely to be produced from typical foam nozzles used on the airfield. Two of the leading F3 products also failed the gentle EN1568-3 Heptane fire test with the UNI 86 test nozzle. All these tests were conducted in freshwater and are likely to have been worse had seawater been used.
Refinery testing in Rotterdam on a small 9 metre diameter fuel storage tank containing light gasoline occurred in 2010. Gasoline was ignited and immediately attacked with 7 Litres/min/m2 of aspirated Alcohol Resistant (AR) 3×6 F3 foam at 6% (effectively double strength for a hydrocarbon fuel), with no preburn period, yet no significant control of the fire occurred even after 15 minutes16. The application rate was increased to 18.2L/min/m2 (3 times the NFPA 11 recommendation for portable monitor use at 6.5L/min/m2) for a further 15 minutes, with still little or no impact on the fire. It eventually extinguished after 31 minutes when all the fuel burnt away16. 2 weeks before, this 9m diameter tank of light gasoline had previously been extinguished in just 2 minutes, using a fluorotelomer based AR-AFFF 1×3 foam at this Refinery’s regular 10.4L/min/m2 application rate16.
Contrast this fundamentally poor F3 performance with a 82 metre diameter fully involved Gasoline tank fire at Orion Refining in 2001 which had been burning
for 12 hours before being extinguished in 65 minutes at an application rate of 8.55L/min/m2 also with AR-AFFF17. Subsequently 25 million litres of gasoline were also safely recovered from this tank. Which would you prefer to rely on – fluorinated or fluorine free agents, to protect your most valuable assets?
This article will be continued in the March issue, where we examine what causes fluorine free foams to suffer these fundamental problems, particularly when forcefully applied to volatile fuels like gasoline.
We also look at aquatic toxicity issues and the interesting findings from a recent Australian firefighter study. Take a sneak preview with this captivating you tube link… just Google “ flammable firefighting foam!22” and keep reading the next issue for part 2, to find out more…
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- European Union, 2006 – Directive 2006/122/EC, PFOS restriction from use across EU after 27 June 2011 http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:372:0032:0034:en:PDF
- Environment Canada, 2008 – SOR 2008-178 Perfluorooctane Sulfonate and its Salts and Certain Other Compounds Regulations http://laws-lois.justice.gc.ca/eng/regulations/SOR-2008-178/page-1.html
- NICNAS, 2015 – Inventory Multi-tiered Assessment and Prioritisation (IMAP) Environmental Tier II Assessment for Short Chain PerfluoroCarboxylic Acids and their direct precursors, http://www.nicnas.gov.au/chemical-information/imap-assessments/imap-assessments/tier-ii-environment-assessments/short-chain-perfluorocarboxylic-acids-and-their-direct-precursors
- Clyde and Co, 2010 – Buncefield Explosion – Fines and Costs £9.5million, http://www.clydeco.com/uploads/Files/Publications/2010/Buncefiled%20explosion.pdf
- US Environmental Protection Agency (EPA),2015 – PFOA stewardship program update – reported reductions in 2014 stewardship reports, http://www2.epa.gov/sites/production/files/2015-10/documents/2014_stewardship_web_site_table_final.pdf
- European Chemicals Agency (ECHA),2015 –Committee for Socio Economic Analysis (SEAC) opinion on restrictions for PFOA, its salts and related substances, http://echa.europa.eu/documents/10162/563e9186-6fde-442f-94db-fc7cd534054e
- Dynax ,2015 – C6 Fluorotelomer technology for firefighting applications, http://www.dynaxcorp.com/technology/firefighting.html
- Hoke et al, 2015 – Screening risk assessment for 6:2 Fluorotelomer sulfonate (FTS), Chemosphere_128_258-265, 2015.
- Korzeniowski S et al, 2013 –Biodegradation, Toxicology and Biomonitoring: AFFF Fluorotelomer based Short-chain Chemistry, Reebok Conference, Bolton, UK March 2013
- Chengalis, C.P. et al., 2009 -Comparison of the toxicokinetic behaviour of perfluorohexanoic acid (PFHxA) and nonafluorobutane -1-sulfonic acid (PFBS) in monkeys and rats. Reprod. Toxicol. 27, 400-406
- Kaunig, Iwai et al, 2014 –Evaluation of Chronic Toxicity & Carcinogeneity of PFHxA in Rats. Toxicol.Pathology ,May2014 DOI: 10.1177/0192623314530532
- Barmentlo et al, 2015 – Acute and Chronic toxicity of short-chain PFAS to Daphnia, Environmental Pollution DOI: 10.1016
- Russell, Nilsson, Buck, 2013 – Elimination Kinetics of PerFlouroHexanoic Acid in Humans and comparison with mouse, rat and monkey, Chemosphere, Sep2013 ISSN 1879-1298 http://www.biomedsearch.com/nih/Elimination-kinetics-perfluorohexanoic-acid-in/24050716.html
- Environ International , 2014 – “Assessment of POP Criteria for Specific Short-Chain Perfluorinated Alkyl Substances” prepared for FluoroCouncil. http://www.fluorocouncil.com/PDFs/Assessment-of-POP-Criteria-for-Specific-Short-Chain-Perfluorinated-Alkyl-Substances.pdf
- Jho C, 2012 – “Flammability and degradation of fuel contaminated fluorine-free foams”, International Fire Fighter, Dec 2012, MDM publishing.
- German Refinery, 2010 – Fire tests conducted at refinery and Falck-Risc Training Centre, Rotterdam small storage tank with re-healing F3 foams (which failed) – personal communication. (Confirming other personal communications from other sources).
- Persson & Lonnemark, 2004 – Tank Fires: Review of fire incidents 1951–2003, BRANDFORSK Project 513-021, SP Sweden.
- Schaefer T, et al, Sealability Properties of Fluorine-Free Firefighting Foams, University of Newcastle, Australia, 2008, Fire Technology Vol 44.issue 3 pp297-309 http://novaprd-lb.newcastle.edu.au:8080/vital/access/manager/Repository/uon:4815;jsessionid=E0140D586B0467E75B68993EBC83A1CA?exact=sm_subject%3A%22vapour+suppression%22
- Caltex, 2014 – Case Study: Banksmeadow Unleaded Petrol Release 2013, HazMat Conference, Preston Victoria,2014
- Sjöström et al, 2015 – Etankfire – Experimental Results of Large Ethanol Fuel Pool Fires, SP Sweden.
- Hubert, Jho & Kleiner, 2012 – Independent Evaluation of Fluorine Free Foams (F3) – A Summary of ICAO Level B and EN1568 Fire Test Results, Asia Pacific Fire p37-39, September 2012. www.mdmpublishing.com/mdmmagazines/magazineapf/
- Flammable firefighting foams! (You Tube video), 2012 – Laboratory testing to verify fuel pickup of F3 foams www.youtube.com/watch?v=IuKRU-HudSU