All extinguishers are rated as to the size of fire they are designed to handle. The rating is a number from 1 to 40 for a “Class A” fire, and 1 to 640 for a “Class B” fire. For example, a 20-B rated extinguisher can handle a flammable liquid fire twice as big as a 10-B extinguisher; the rating will appear on the label.

“Shooting” a CO2 or pressurized dry chemical extinguisher results in a puncture and very rapid discharge of the contents. If the extinguisher is not restrained, it will be propelled by the discharge in erratic and potentially dangerous vectors.

Fire extinguishers with a Class A rating are effective against fires involving paper, wood, textiles, and plastics. The primary chemical used to fight these fires is monoammonium phosphate, because of its ability to smother fires in these types of materials.

They contain an extinguishing agent and use a compressed, non-flammable gas as a propellant. Halon extinguishers contain a gas that interrupts the chemical reaction that takes place when fuels burn.

Here’s how it works: The Class A size rating represents the water equivalency. Each number represents 1 ¼ gallons of water. For instance, 2A means the extinguisher is just as effective as 2 ½ gallons of water.

Compartment fire development can be described as being comprised of four stages: incipient, growth, fully developed and decay (see Figure 1).

Reducing heat on wildfires may be accomplished in two ways: cooling with water, foam, dirt, or scattering the available fuels to reduce the effect of radiant heat. Water or dirt should be directly applied on the fuels being consumed to reduce fuel temperature.

The fire service adds that there should also be one plug in each socket. Many appliances plugged into a socket with a multi-way adaptor can overload the circuit, causing a fire that can produce sufficient carbon dioxide to suffocate someone.