Fire Extinguisher Ratings

Old Icon Label | New Label		Classification
		Class A Extinguisherswill put out fires in ordinary combustibles, such as wood and paper. The numerical rating for this class of fire extinguisher refers to the amount of water or dry chemical the fire extinguisher holds and the amount of fire it will extinguish.
		Class B Extinguishersshould be used on fires involving flammable liquids, such as kitchen grease, gasoline, kerosene, paint, oil, etc. The numerical rating for this class of fire extinguisher states the approximate number of square feet of a flammable liquid fire that a non-expert person can expect to extinguish. NEVER USE WATER
		Class C Extinguishersare suitable for use on fires involving electrical equipment or wires. This class of fire extinguishers does not have a numerical rating. The presence of the letter “C” indicates that the extinguishing agent is non-conductive. NEVER USE WATER
		Multi-Class Ratings Many extinguishers available today can be used on different types of fires and will be labelled with more than one designator, e.g. A-B, B-C, or A-B-C. Make sure that if you have a multi-purpose extinguisher it is properly labelled.

Types of Fire Extinguishers

Multi-purpose – Dry Chemical These extinguishers are usually rated for multiple-purpose use. They contain an extinguishing agent and use a compressed, non-flammable gas as a propellant. Dry chemical extinguishers are usually rated for class B and C fires and may be marked multiple purpose for use in A, B, and C fires. Dry chemical extinguishers put out fires by coating the fuel with a thin layer of fire retardant powder, separating the fuel from the oxygen. The fire retardant powder works by suffocating the fire, inhibiting the release of combustible vapours and interrupting the combustion chain reaction, which makes these extinguishers extremely effective. ABC fire extinguishers are red in colour, and range in size from 2.27 kg to 9 kg (5 to 20 pounds). Dry Chemical extinguishers will have a label indicating they may be used on class A, B, and/or C fires.

Water – Air-pressurized Water (APW) These extinguishers contain water and compressed air and should only be used on Class A (ordinary combustibles) fires. Water is one of the most commonly used extinguishing agents for type A fires. You can recognize an APW by its large silver container. They are filled about two-thirds of the way with ordinary water, then pressurized with air. In some cases, detergents are added to the water to produce a foam. They stand about .6 to 1 metre tall (2 to3 feet) and weigh approximately 11.5 kg (25 pounds) when full. APWs extinguish fire by cooling the surface of the fuel to remove the "heat" element of the fire triangle. APWs are designed for Class A (wood, paper, cloth, upholstery, rubber, and certain plastics) fires only. Important: Never use water to extinguish flammable liquid fires (Class B). Water is extremely ineffective at extinguishing this type of fire and will make matters worse by the spreading the fire. Never use water to extinguish an electrical fire (Class C). Water is a good conductor and may lead to electrocution if used to extinguish an electrical fire. Electrical equipment must be unplugged and/or de-energized before using a water extinguisher on an electrical fire.

Carbon Dioxide (CO2) These extinguishers are most effective on Class B and C (liquids and electrical) fires. This type of extinguisher is filled with Carbon Dioxide (CO2) gas, a non-flammable gas under extreme pressure. These extinguishers put out fires by displacing oxygen, or taking away the oxygen element of the fire triangle. Because of its high pressure, when you use this extinguisher pieces of dry ice shoot from the horn, which also has a cooling effect on the fire. Since the gas disperses quickly, these extinguishers are only effective from 1 to 2-1/2 metres (3 to 8 feet). Since the fire could re-ignite, continue to apply the agent even after the fire appears to be out. You can recognize this type of extinguisher by its hard horn and lack of pressure gauge. CO2 cylinders are red and range in size from 2.27 kg to 45.36 kg (5 to 100 pounds) or larger. CO2 extinguishers are designed for Class B and C (flammable liquid and electrical) fires only. Important: CO2 is not recommended for Class A fires because they may continue to smoulder and re-ignite after the CO2 dissipates. Never use CO2 extinguishers in a confined space while people are present without proper respiratory protection.