The NFPA 11- Standard for Low, Medium and High Expansion Foam (Table 5.8.2.2.) states foams must be applied to a nondiked hydrocarbon spill for a minimum of 15 minutes at an application rate of 0.10 gpm/ft2 or 3%. A “nondiked spill” describes a real world spill situation where the fuel spreads freely, not confined by walls or barriers.
As an example, assume 8 gallons of gasoline has spilled on the highway. Eight gallons equates to an 800 sq. ft. spill. To completely encapsulate the spill, 1-gallon of F-500 EA would need to be added to 40-gallons of water. This is a calculated and tested ratio of 1 part F-500 EA, 8 parts fuel and 40 parts of water. The firefighter would set the F-500 EA eductor to 3% and encapsulate the spill in about 30 seconds with an 80 gpm nozzle and handline. In contrast, the foam will need to be applied for 15 minutes, per the NFPA foam standard. At 3%, using an 80 gpm nozzle, 1,200 gallons of water will be applied and 36 gallons of AFFF foam. If the foam blanket breaks down while the gasoline temperature is still high, additional foam will need to be applied.
The cost of F-500 Encapsulator Agent is comparable to the AFFF foam, but only one gallon of F-500 EA was required compared to 36 gallons of foam. The spill would more than likely be a gasoline/ethanol blended fuel, such as E10, in which case, a more expensive AR-AFFF foam would have been required. In a remote highway setting, the pumper truck would need to be carrying 1,200 gallons or more of water.
Finally, F-500 EA is listed by the EPA as a “surface washing agent.” Once the spill has been encapsulated it can be easily cleaned up as a nonflammable material, or allowed to evaporate, if permitted by local regulations. On the other hand, the application of foam has left 1,200 gallons of water and 36 gallons of foam. The fuel is still hazardous and flammable and must be removed and hauled away at great expense. Applying absorbent soaks up the fuel, but now the absorbent is flammable. The 1,200 gallons of water are going to run-off somewhere, which could harm the environment or result in fines.
In this chart, you can see the various firefighting agents required to fight different fires. Pumper trucks carry various foams and agents to handle these hazards when all they really need to carry and inventory is F-500 Encapsulator Agent.
