Most foam users recognise the need for transitioning away from legacy firefighting foams that break down to long-chain C8 PerFluoroAlkyl Substances (PFAS), including PFOS, PFOA and PFHxS (C8s), because of potentially harmful effects to human health and our environment.
The big question is: what should we use to replace those legacy C8 foams to ensure effective outcomes? Do we choose Fluorine Free Foams (F3s) without key benefits relied upon for decades to keep us safe? Or do we accept more benign high-purity short-chain C6 PFAS foam alternatives (C6s), achieving reliable, fast-acting, fuel-shedding, vapour-sealing extinguishment, without perpetuating that C8 legacy? Avoiding unintentional compromises to original system design objectives is key to protecting lives, critical infrastructure and communities from harm when making such pivotal decisions.
Moving from legacy C8 Foams
PFAS embraces a wide, diverse variety of fluorinated chemicals, including undesirable legacy 8 carbon chain length (C8) substances which breakdown to PFOS and PFOA, confirmed Persistent, Bioaccumulative and Toxic (PBT) and listed Persistent Organic Pollutants (POPs) under the UN Stockholm Convention (PFOS since 2009). Legacy C8 PFHxS is also being POP listed. Adverse environmental impacts, accumulation in fish, seafood and drinking water contamination cause potential human health issues from extended exposure to such C8 chemicals, with long human half-lives (averaging 3 to 8.5 years). C8s can build up in our bodies over time to levels of concern, particularly those occupationally exposed, like firefighters, hence necessary transition.
C6 PFAS behave very differently, being categorised not Bioaccumulative, not Toxic. C6 are still Persistent, although without ‘B and T’ potential for harm is substantially reduced. C6 PFHxA’s human half-life averages 32 days, PFBA (C4) averages just 72 hours, both quickly excreted in urine, preventing bodily build-up over time.
Australia’s Government Health Department expert PFAS panel reported in 2018 regarding PFAS (both long and short-chain) exposure: ‘There is no current evidence that supports a large impact on an individual’s health.’ and ‘In particular, there is no current evidence that suggests an increase in overall cancer risk.’ It concluded: ‘Our advice to the Minister in regards to public health is that the evidence does not support any specific biochemical or disease screening, or health interventions, for highly [PFAS] exposed groups, except for research purposes.’
Key is avoid harming lives and critical assets, and adverse environmental impacts
Could reliance on Fluorine Free Foams (F3s) avoid these harms? Or, risk unknowns, potentially unforeseen consequences to life safety? Are potential liabilities, consequences and complexities fully appreciated when trying to achieve equivalency? Particularly when major incidents and extensive evidence from comparative F3 testing suggests significantly higher F3 application rates, slower extinguishment times, less flexibility and specific fuel vulnerabilities. Little large-scale F3 testing seems yet conducted. So how do we know lives will be adequately protected?
It’s a dilemma now facing many foam users at Major Hazard Facilities (MHFs) including:
- refineries, chemical plants, storage tank farms
- offshore platforms, distribution terminals, bulk transportation (road, rail, ships, pipelines)
- existing fixed foam systems, plus airports and military facilities.
How can we ensure life safety is not compromised?
Many factors need consideration
It requires careful consideration before making such critical decisions. Ask searching questions. What implications, consequences and misleading assumptions could result from potentially inferior fire protection in future? More clarity follows in this complex, sometimes contradictory area of how we can best protect lives, communities, jobs, businesses, critical infrastructure while minimising environmental harm from future major fires. Steering the best path for your needs can be challenging but seems achievable.
Adapting existing C8 foam systems to very different F3 use, without fuel repellency and reduced vapour sealing (provided by C6s) can be problematic. Annex H in NFPA 11’s latest 2021 edition highlights important NFPA Research Foundation (NFPA-RF) findings, including F3s are NOT ‘Drop-in’ replacements for fluorinated foams. Their fire capabilities vary significantly, making it difficult to develop any ‘generic F3 design standards’ to reliably support major incident control. Such inability to use F3s in existing system designs without significant re-engineering and equipment changes adds complexity, implications and consequences beyond many users’ and regulators’ expectations.
Have we factored higher F3 application rates, extra storage, different hydraulics, potentially larger pipe diameters or pressures into our transition plans? NFPA-RF confirmed F3s at 3-4:1 expansion require 25–50% more foam than 7–8:1 on gasoline. Delivery device changes, higher pressures, larger pumping capacities, shorter reach, also more wind effects are likely. What about incident escalation and fire burnback, without fuel shedding abilities? Might firefighter safety be compromised? Extra firewater run-off could overflow containments, creating far worse outcomes than expected. We’ve already seen it happen in Australia. Has alternative stand-by protection during ‘shut-down’ been considered to allow F3 re-engineering works? Could transition to C6 deliver improved outcomes without re-engineering?
More potential challenges
Potential viscosity differences, proportioning accuracy, mixing ability, storage stability, corrosion effects, clean-out procedures, all are important pre-requisites to any transition. Rigorous review of fire testing to establish effective design application rates for site fuels is essential. Ensure nozzle changes, delivery rates, proportioners, expansion ratios meet listed expectations. Confirm current life safety and critical asset protections will not be compromised. Summarise actions, changes, costs, clean-out procedures, containment into bunded areas, safe remediation and disposal. Document your process. Include final wash-water lab analysis, confirming low residual C8 PFAS levels meet Authority Having Jurisdiction (AHJ) requirements. Consider containment improvements for C6 foam usage, preventing environmental escape during emergencies and re-engineering.
Delivering reliable, fast, effective and efficient system activation – without endangering lives, without containment over-flows – goes a long way to ensuring obligations are met, should subsequent major fires occur. The UK’s Environment Agency sums it up: ‘foam buyers’ primary concern should be which foam is the most effective at putting out the fire. All firewater and all foams present a pollution hazard. …the best technique is to prevent pollution from entering in the first place.’
Are firefighting foam approvals misleading us?
Some see F3s as their only option, but that may risk causing bigger problems. Most existing fire test approvals (e.g. UL162, FM5130, EN1568-3, ISO7203-1, Lastfire, IMO) use heptane as a consistent repeatable test fuel. NFPA-RF and 2019 US Naval Research Laboratory (NRL) comparative fire testing confirm heptane might not be a good surrogate for all hydrocarbon-based fuels (e.g. gasoline/E10), particularly with F3s. It recommends F3s be listed on the various hydrocarbon fuels stored/used on site. An approach already used for polar solvent listing.
NFPA-RF testing established that: ‘The extinguishment densities for the FFFs [AR-F3s and F3s] were typically 2 to 4 times greater than the baseline AR-AFFF [C6] for the IPA [IsoPropyl Alcohol] fires at Type II [gentle] application, 3 to 4 times greater than the baseline AR-AFFF [C6] for the tests conducted with MILSPEC gasoline and between 6 to 7 times greater than the baseline AR-AFFF [C6] for the tests conducted with E10 [gasoline with 10% ethanol added].’ Existing heptane approval ratings clearly mislead us. Separate independently verified approval listings confirming suitability criteria on these fuels at your sites now seems essential to avoid compromising site safety, and before any transition.
Clear guidance necessary
Clear and unambiguous guidance is surprisingly tricky to find. Many have found Fire Protection Association Australia’s May 2020 guidance document ‘Selection and Use of Firefighting Foams’ insightful, sensible and balanced. Its available for free download at http://www.fpaa.com.au/technical/technical-documents/information-bulletins/ib-06-v11-selection-and-use-of-firefighting-foams.aspx
NFPA 11:2021’s Annex H.2.3 highlights important NFPA-RF findings: ‘FFFs [AR-F3s and F3s] are not a “drop-in” replacement for AFFFs. However, some can be made to perform effectively as an AFFF alternative with proper testing and design (i.e. with higher application rates and densities). … Ultimately end users will need to design and install [systems] within the listed parameters to ensure a high probability of success during an actual event.’ Annex H.2.2 also confirms: ‘For the FFFs [AR-F3s and F3s] in general, the firefighting capabilities of the foams varied from manufacturer to manufacturer making it difficult to develop generic design requirements.’… ‘To summarise the results, the baseline C6 AR-AFFF demonstrated consistent, superior firefighting capabilities through the entire test program under all test conditions. [my emphasis]’
NRL fire testing concluded four key aromatics in gasoline (Trimethylbenzene, Xylene, Toluene, Benzene) attack F3s, causing higher application rate demands over heptane and reduced burnback abilities.
Be aware of potential consequences
Little realistic large-scale F3 fire testing has been conducted to verify effectiveness on major fires. Contrasting outcomes from two major fires provide some insight.
Australia’s August 2018 chemical fire was the largest Melbourne had seen for decades. Occurring in Footscray’s residential suburb, 50 schools were closed and 19 suburbs ‘locked-down’ due to thick black smoke hazards. Control reportedly 17 hours followed by five days to fully extinguish (some areas were heavily shielded, causing extra delays). EPA Victoria confirmed: ‘the foam used by Melbourne’s Fire Brigade did not contain PFAS’. Acetone, Butanone, BTEX (Benzene, Toluene, Ethylbenzene, Xylene), Phenols, and detergent chemicals were involved. Firewater run-off quickly overflowed containments, poisoning the nearby creek. 55 million litres of contaminated run-off was pumped from this creek by day 3. 170 million cubic metres of contaminated sediment was removed three weeks later. January 2020 saw creek remediation continuing. PFOS/PFOA were detected at 16 times above permitted creek levels for two weeks downstream of the fire site, presumably from site equipment.
EPA Victoria’s Chief Environmental Scientist confirmed Footscray was ‘probably as bad as it could be. The chemicals from the fire have had a “massive impact” on the creek system – we’ve had more than 2,000 fish killed.’ October 2019 saw 30 firefighters still experiencing illnesses following their multi-day attendances at Footscray’s fire, suffering symptoms of fainting, headaches, nose-bleeds, fatigue, dizziness, nausea, possibly from toxins and excess smoke exposure. Did slower fire control deliver worse outcomes?
Contrast this with a major 1996 chemical fire at Avonmouth, UK. This was another chemical complex with fuel storage depots, major docks, industrial units and two significant residential areas all within a 2.5km radius. Estimated petrochemical inventory was 220,000 litres. An Epichlorohydrin road tanker provoked an explosion and major 2,400m2 fire, which was quickly extinguished in four hours, using AR fluorinated foam. The truck driver and seven operatives ran to safety, while starting plant shut-down. Surprisingly no severe injuries, illnesses or fatalities occurred.
In Houston, Texas, April 2021 a massive K-SOLV chemical cocktail fire, including Acetone, Ethanol, Toluene and Xylene, was reportedly extinguished in four hours, controlled in just two. No injuries were reported among 95 employees working on site. Monitored smoke pollution levels were low concern, with no firewater run-off escapes reported. Houston is home to 2,500 chemical sites, with a major chemical incident reported every six weeks.
Successful firefighting involves many factors, and foam choice usually makes a contribution. When fire strikes your facility, how well will you manage?
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