C6 Foam Is Proving More Environmentally Reliable

A January 2019 article “The price of fire safety” published in Chemical and Engineering News by Marc Reisch, gave a valuable overview of the complex issues currently surrounding firefighting foams.

Contamination issues at fire training facilities (particularly airports and defense sites) from intensive training use over decades, is raising government pressure, and focusing attention on the environmental costs of legacy PFOS and PFOA usage.

This problem only arose because everyone was assured these “surfactants would do no harm when they got into the environment.” Consequently, tough management practices to capture and treat these firefighting foams were not originally put in place, but increasingly have been since 2006.

We now seem to be paying a high price for those errors of judgement, in terms of C8 legacy PFOS and PFOA contamination from concentrated fire training regimes.

Ted Schaefer, former 3M formulation scientist confirmed to Marc “The 3M scientists were wrong. In 2000 the company admitted that surfactants based on perfluorooctane sulfonic acid (PFOS), which were used in Light Water, were accumulating in the environment and showing up in humans and animals at levels that raised health questions.

Similar fluorosurfactants based on per-fluorooctanoic acid (PFOA), another eight-carbon fluoro-chemical, have been linked to human health concerns as well.” PFOS was listed as a Persistent Organic Pollutant (POP) under the Stockholm Convention in 2009. 3M voluntarily stop-ped their production of what is now known as legacy firefighting foams containing PFOS and PFOA and their related substances, from manufacturing sites globally in 2002-2003.

Under the US EPA PFOA Stewardship program (2006-2015) manufacturers voluntarily sought elimination of PFOA from their products, processes and waste streams. The foam industry has since successfully transitioned to environmentally more benign high purity short-chain C6 fluorotelomer chemistry.

To prevent environmental exposure, Marc confirms foam makers have called on all users to stop training and testing exercises using fluorosurfactant-containing foam (unless it is contained 100 percent). Using Fluorine Free Foams (F3s) for fire response instead without containment, may not prevent problematic groundwater contamination from other PFAS sources contained in firewater runoff.

More F3 usage could also cause more severe BOD problems, yet some are championing these alternative F3s as “capable alternative front-line agents — as good as the fluorosurfactant-based foams.” But are they really?

U.S. NRL Testing Fails F3s

Many firefighting experts, including US military scientists consider fluorosurfactant foams essential to protecting life and property, because, they provide superior fuel repelling, vapour sealing qualities, which are unrivalled. These qualities are absent in foams without fluorosurfactants, so F3s suffer slower, less effective, less reliable fire performance, particularly when applied forcefully into volatile fuel fires, including Jet A1 and gasoline.

Researchers at the U.S. Naval Research Laboratory (NRL) writing military firefighting foam specifications are actively looking at fluorine-free alternatives, but Marc reports “they haven’t found any that meet required performance standards that include extinguishing a 2.6 m2 test fire in as little as 30 secs.”

This tough requirement was discussed with several staff at NRL, including John Farley, director of fire test operations who said “The lab has qualified 16 firefighting foams containing C6 chemistry … We need to come up with fluorine-free foam, but what’s available now can’t meet specification.”

Katherine M. Hinnant, a chemical engineer leading NRL firefighting foam research, said “fluorinated foams outperform fluorine-free foams (F3) by a factor of four to five, by containing a fire and suppressing vapors that can reignite. Fluorine-free foams are stable for three minutes, while the fluorosurfactant kind can last 30 min.”

Hinnant’s 2015 research showed F3s required 40 seconds to extinguish, compared to AFFF extinguishing in just 18 seconds. In the search for more effective fluorine-free foams, Hinnant confirmed she is “evaluating hydrocarbon surfactants, silicones, and sulfonated surfactants. Fluorine is really amazing,” but “we are focusing on eliminating fluorine.”

2017’s Department of Defense’s Strategic Environmental Research and Development Program (SERDP) awarded $2.5 million over 3 years to F3 development projects.

Hinnant and other government researchers are well aware that F3 without fuel shedding capabilities (similar to current versions), was unable to control a major fire on the USS Forrestal in 1967. One hundred and thirty-four sailors died, another 161 badly injured, 21 aircraft destroyed and 40 more damaged on board this aircraft carrier.

Avoiding similar catastrophes accelerated development of fluorosurfactant containing AFFFs. Care is needed that we are not “winding the clock back” — potentially risking more tragedies — without major improvements to current F3 performance.

Witness the recent challenging ITC Deer Park tank farm fire in Texas, with firefighting hindered by strong cross winds. Industrial Fire World Spring edition’s valuable insight into this fire showed it started with a single tank fire, escalating into “a complex maze of extreme hazards bunched close together including manifold fires with running boiling liquid and hot steel,” spreading to 12 of the 15 congested tanks in the same dike.

Only on the third day, when Dwight Williams was coaxed out of retirement to use his new C6 1x3 AR-AFFF were his combined lifetime of skills plus those of his team members finally utilized to get the fire out, preventing its spread across a pipeline into another diked tank area and another tank farm. Dwight confirmed “it was one of the top three most challenging burns that I’ve ever dealt with.” How would F3s have fared under these challenging conditions?

Marc’s C&E News reported Solberg’s Global Product Development Vice President Mitch Hubert, made the case for C6 fluorochemical foams at Washington State’s February 2018 foam legislation hearings, testifying “The fluorine-free foams are very effective on spill fires, …but when those foams are used on fuel-tank fires, the foam plunges below the surface, picks up fuel, and contributes to the fire.”

Australia’s chemical regulator (NICNAS) in its 2015 Environmental risk assessment confirms that although still persistent, short-chain C6 chemistry is safer because it is “not bioaccumulative, not toxic” in the environment. It’s 2016 occupational and public health risk characterisation also confirmed “C6 chemicals are not considered to pose an unreasonable risk to workers’ health” and “the public risk from direct use of these chemicals is not considered to be unreasonable.” 

Further extensive research confirms the main C6 breakdown product PFHxA is not carcinogenic, nor mutagenic, nor genotoxic, nor a reproductive toxicant (Iwai 2011 & 2012, Serex 2008, Loveless 2009, Chengalis 2009, Korzeniowski 2013). 2013 work by Russell’s team established a PFHxA human half-life of just 32 days, being excreted in urine.

By contrast, Olsen’s team in 2007 had already established legacy PFOS, PFOA and PFHxS have human half-lives averaging between 3 and 8 years. PFOS was POP listed (Persistent Organic Pollutant) in 2009 under the Stockholm Convention with PFOA and PFHxS following, based on their proven persistent, bioaccumulative and toxic categorisations, and their human health concerns.

A 2018 Australian Department of Health, Expert PFAS Panel report confirmed that “there is no current evidence that supports a large impact on an individual’s health.” There's more. “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 [of PFAS] is that the evidence does not support any specific biochemical or disease screening, or health interventions, for highly exposed groups - except for research purposes.” This suggests that short-chain C6 flurotelomers are not currently seen as a human health concern.

Mil Spec allows F3 from October 2020, but only if all performance standards are met.

October 2018's FAA (Federal Aviation Administration) Re-Authorization Bill accepted non-fluorinated foam use from 2020. Table 1 (see Page 18) highlights important supplementary Mil Spec criteria with which most current F3s cannot comply.

Speed and Reliability Critical for Life Safety

Quick arrival, then effective, efficient, reliable, fast fire control and extinction of volatile fuel hazards is critical to saving lives and preventing escalation. Fluorosurfactants have unique benefits necessary to prevent mixing with fuel and improve vapour suppression, to reliably achieve these expectations.

Industry is voluntarily transitioning away from foams still including undesirable legacy long-chain C8 ingredients and breakdown products, to more environmentally benign high purity short-chain C6 fluorotelomer surfactants, recognized as neither bioaccumulative, nor toxic. F3 agents are also being used where safe to do so, particularly in firefighter training and systems testing.

Potential consideration for use in Municipal Fire Department applications is occurring on smaller less hazardous fires without containment. Whether C6 AFFFs or F3s are used in emergencies without retention, both could represent a potential problematic groundwater contamination risk. F3s also struggle with larger more volatile in-depth fires likely in Major Hazard Facilities (MHFs) including airports, helidecks, offshore, military, refineries, fuel terminals, chemical plants, etc.

Large volatile fuel stores at MHFs demand our best fire protection. It saves lives, protects critical infrastructure, minimizes escalation risks, protects neighboring properties and nearby communities, while protecting the socio-economic benefits these facilities provide to the continued economic well-being of these United States. Isn’t that an issue of National Security?

As the NRL research confirms, current F3s are generally proven significantly less effective than AFFFs even in small scale comparative fire testing. We have yet to see larger scale F3 testing. AFFF performance has been verified at numerous documented large scale fires, including recent ITC tank fires in Texas, proving its suitability beyond doubt.

Current F3s are still plagued by edge flickers, sudden and unpredictable flashbacks, fuel pick-up, and poor vapour suppression, so they continue burning longer — particularly when forcefully applied to volatile fuels (eg. gasoline, Jet A1), in-depth (i.e. ≥ 25mm deep — less than this is defined as a spill fire) and under warmer summer conditions.

As U.S. NRL's director of fire test operations says “We need to come up with fluorine-free foam, but what’s available now can't meet specification.” Meanwhile, relying on effective, more environmentally benign high purity C6 fluorotelomer based AFFFs and AR-AFFFs, seems to provide the essential life safety and critical asset protection society needs and expects.

Contact Mike Willson at [email protected].