by Joan Leedy, Technical Director

There are two types of class-B firefighting foam available on the market today – foams containing per or polyfluoroalkyl substances (PFAS) and foams that are fluorine free, meaning they are not formulated to contain PFAS. Some states have mandated the use of synthetic fluorine free foam (SFFF) for certain applications. But if your application is not covered by such a mandate, you have to choose whether to purchase a SFFF or a PFAS containing foam. Let’s take a look at how these two types of foam differ.

Property

PFAS Containing Foams

Synthetic Fluorine Free Foams

Types

  • Aqueous Film Forming Foam (AFFF)
  • Alcohol Resistant AFFF
  • Fluoroprotein Foam
  • Alcohol Resistant Fluoroprotein Foam
  • Film Forming Fluoroprotein Foam
  • Alcohol Resistant Film Forming Fluoroprotein

 

  • SFFF
  • Alcohol Resistant SFFF

Formulations

Formulated with water, solvents, hydrocarbon surfactants and PFAS. In the past contained first generation PFAS molecules such as PFOS[i] and PFOA[ii]. Today they are formulated with six or less carbons to reduce potential toxicity.

Formulated with water, solvents and hydrocarbons surfactants. Definition in proposed new edition of NFPA 11 is “Concentrate based on a mixture of hydrocarbon surface active agents that is not formulated to contain per- or polyfluoroalkyl substances (PFAS).

Film Formation

The PFAS in the foam reduces the surface and interfacial tension of the foam solution and enables it to form an aqueous film on the surface of many hydrocarbon flammable liquids. This aqueous film aids in fire extinguishment and reignition by preventing the evaporation of vapors.

Because there is not PFAS in the formulation, SFFFs do not form this aqueous film. SFFFs rely solely on the foam blanket to extinguish the fire.

Foam Expansion

Because the foam can form a film the foam blanket can be effective at lower foam expansion values such as 3:1 to 5:1. This allows use through non-air aspirated nozzles which often provide greater reach.

Testing done to date has concluded that a higher expansion rate of 7:1 to 10:1 is required. This may require the use of air aspirated nozzles or other application devices and may limit reach.

Environmental, Toxicity

PFAS do not easily break down in the environment and may bioaccumulate causing toxicity concerns. Foam sprayed on the ground can leach into the ground water and contaminate wells. Consult the Safety Data Sheet (SDS) for specific information regarding the environmental and toxicity properties.

Formulated with less environmental impact. SFFF more easily breaks down in the environment, does not bioaccumulate. Consult the Safety Data Sheet (SDS) for specific information regarding the environmental and toxicity properties.

Equipment

All equipment should be listed or approved for use with the foam concentrate.

All equipment should be listed or approved for use with the foam concentrate. If changing a system from a PFAS foam to a SFFF, evaluate the compatibility of the SFFF and the existing equipment. Check to make sure the foam expansion is sufficient, the SFFF will proportion correctly and the application density is sufficient.

Regulations

Some states have restricted use of PFAS foams in specific applications. Additionally, many states restrict the discharge of PFAS foam for training or testing. Check local regulations for proper disposal of the foam concentrate and foam solution.

It is unlikely that a SFFF would be restricted for use in any fire protection applications but discharge of foam for training or testing may still apply. Check local regulations for proper disposal of the foam concentrate and foam solution.



[i] PFOS – perfluorooctanesulfonic acid

[ii] PFOA – perfluorooctanoic acid

Should you want to confirm whether your foam contains PFAS or not, Dyne Fire Protection Labs offers analytical services to detect PFAS in foam concentrate, foam solution, bladder water and other water systems. Using combustion ion chromatography (ICI) techniques, Dyne can detect the total organic fluorine level in liquid substrates down to 1 parts per million (ppm).

If you have any questions regarding this article, please contact Dyne Fire Protection Labs at lab@dyneusa.com or (800) 632-2304.

©Dyne Fire Protection Labs 2020

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