HazMat for First Responders (2nd Edition)
Chapter 7 - Tactical Priorities & Defensive Control Strategies
"By the Numbers"

  • Foam quality is measured in terms of its 25% drain time and its expansion ratio.
  • The 4 elements necessary for high-quality foam are Foam Concentrate, Water, Air, and Mechanical Agitation (aeration).
  • Foam concentrate is usually stored in 5 gallon pails, 55 gallon drums, or in apparatus storage tanks.
  • Firefighting foam is 94% to 99.9% water.
  • Foams in use today are designed to be used at 1/2%, 1%, 3%, or 6%.
  • Class A foams are used at 1/2% or 1%.
  • Foams for hydrocarbon fires are used at 1% to 6%.
  • Foams for polar solvent fires are used at 3% to 6%.
  • Medium and high expansion foams are generally used at 1 1/2%, 2%, or 3%.
  • AFFF and FFFP have air/solution ratios from 7:1 to 20:1.
  • Low expansion foams work best when the fuel liquid temperature is less than 212oF.
  • Medium expansion foams have expansion ratios from 20:1 to 200:1.
  • High expansion foams have expansion ratios from 200:1 to 1,000:1.
  • All AFFF and FFFP foams require an application rate of 0.10 gpm foam solution per square foot for ignited hydrocarbon fuels and 0.20 gpm for polar solvents.
  • Protein and fluoroprotein foams should be applied at a rate of 0.16 gpm per square foot on ignited hydrocarbon fuels.
  • Hydrocarbon fires involving gasoline or diesel transport vehicles will generally require a minimum flow of 60 gpm of foam solution and twenty 5 gallon pails (100 gallons) of foam concentrate.
  • Foam should be re-applied when the 1/4 lifetime limit has been reached or when vapor-measuring equipment indicates vapor emission.
  • Protein and Fluoroprotein foams can be stored at temperatures from 20oF to 120oF.
  • FFFP foams can be stored at temperatures from 10oF to 120oF.
  • Alcohol-resistant FFFP and AFFF foams may be stored at temperatures from 25oF to 120oF.
  • Alcohol-resistant AFFF is used on polar solvent fires at 3% or 6%, but may only be used at 3% on hydrocarbon fires.
  • Alcohol-resistant AFFF may be adversely affected when stored at temperatures below 50oF.
  • Medium and high expansion foam concenatrates may be stored at temperatures from 27oF to 110oF.
  • Air-aspirating nozzles may be either handheld (30 to 250 gpm) or monitor-mounted (250 gpm or more).
  • Inline eductors should be positioned so that they are no more than 6 feet above the foam concentrate.