How to Choose and Use Fire Extinguishers

By: John Kelsey, This Old House magazine (Page 2 of 6)

Photo: Eric Piasecki

Reading the label of a fire extinguisher

Icons: Courtesy of the National Fire Protection Association

Every household extinguisher is labeled A, B, or C. In the fine print, the higher the number preceeding each letter, the greater the extinguisher's effectiveness against each type of fire.

Photo: Eric Piasecki

Amerex B441 10-pound fire extinguisher, rated 4-A:80-B:C, about $85 at safety-supply companies

Photo: Eric Piasecki

First Alert FE3A40 5-pound fire extinguisher with a 3-A:40-B:C rating, about $40.

Photo: Eric Piasecki

Shown: Kidde 466310 2-pound fire extinguisher, rated 5-B:C, about $20 at home center or auto parts store

Firestop, from Williams-Pyro, for the stovetop

Photo: Eric Piasecki

Firestop stovetop fire extinguisher, from Williams-Pyro, about $49 for set of two cans needed to cover four burners.

Illustration: Joel Naprstek

Remember the acronym PASS to use your fire extinguisher: P is for Pull the extinguisher's safety pin.

Aim the chemical at the source of the flames

Illustration: Joel Naprstek

A is for Aim the extinguisher at the source of the flames.

Squeeze the trigger and hold it, keeping the extinguisher upright

Illustration: Joel Naprstek

S is for Squeeze the trigger and hold it.

Illustration: Joel Naprstek

S is for Sweep the source of the flames until the extinguisher runs dry.

Photo: Eric Piasecki

The EN-Gauge sensor system from MIJA flashes a red light and sounds an alert, reminding you to refill your extinguisher.

Photo: Eric Piasecki

The alarm company gets a signal from a fire extinguisher gauge wired to home security system.

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Reading the Label

Every household extinguisher is labeled A, B, or C, which tells you the types of fires the extinguisher is effective against. A is ordinary combustibles like wood, paper, and cloth; B is flammable liquids, such as gasoline or cooking oil; and C is live electricity.

In the fine print on the label, these letters are preceded by numbers — for example, 3-A:40-B:C — which are the extinguisher's classification rating. The numbers, assigned by Underwriters Laboratories, tell the extinguisher's relative effectiveness against each type of fire, regardless of its weight or the chemical it uses. The higher the number, the greater the effectiveness (and likely the higher the price). So an extinguisher with a 4-A rating is more effective on ordinary combustibles than a 2-A one. The C designation carries no number; it just means the extinguisher's chemicals won't conduct electricity.