NFPA 10 Requires "High Flow" Extinguishers

By Mark Conroy

Class B fires involve flammable liquids. The most common type of Class B fire is the “spill fire”. A spill fire occurs when flammable liquid is spilled onto a floor or pavement and an ignition source causes a fire. NFPA 10 addresses this type of fire hazard in Table 6.3.1.1, but this table only applies to spill fires or similar fires.

Here’s why. The ratings used in this Table 6.3.1.1 are based on the fire test standard UL 711, Rating and Fire Testingof Fire Extinguishers. These test fires are conducted in square pans and are actually pools of flammable liquid. The flammable liquid in the pans is not in motion, and these fires don’t have objects in them to interfere with the application of the extinguishing agent. Any fire that is like a UL 711 test fire can be protected according to the Table 6.3.1.1.

However, technicians installing extinguishers for hazards that involve flammable liquids in motion, which are spraying or flowing or where there could be objects in a flammable liquid fire, need to use Section 5.5 of NFPA 10. This is where “high flow” dry chemical extinguishers are addressed for the protection of these hazards. Here is a table of extinguishers that match the requirements in Section 5.5.

*Note: NFPA 10 allows either foam or multiple smaller dry chemical extinguishers to be installed in lieu of high flow extinguishers for obstacle fire hazards.

Make sure your customers are in compliance with NFPA 10. Use the table above for help with matching high flow extinguishers to these unique fire hazards.