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Different Types of Fire Extinguishers for your Workshop

Different types of Fire? Know the Class Category for Fire Extinguishers

by Keith Dooley and Roger Tunsley from

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A garage requires different fire extinguishers for oil, electrical and chemical fires. What you see in an office may not be right "class" of fire extinguisher in your workshop.

If you work with metals only, you are still of course using electrical lighting and electrical tools. Maybe even printed manuals!

Similarly, if you store oil, lubricants and gasoline, you would be better equipped against accidents by using a fire extinguisher which has a "combination" capability against different types of fires.
Ideal Fire Extinguishers for Garages
Auto garages are full of electrical equipment, gasoline, oil and chemicals, any of which can cause or make a fire worse. For this reason, it is best that garages are equipped with several types of fire extinguishers to deal with different types of fire.
For example, what works for an electrical fire might make a gasoline or oil fire worse, or at least may not work well on it.

Class A

Class A fire extinguishers will put out basic fires: wood, paper and other typical material. In an auto shop, this fire extinguisher is best placed in the office area to put out simple fires. It is never to be used on gasoline, oil or electrical fires because it contains water.

Class B

Class B extinguishers are a must in a garage due to all the flammable liquids that mechanics deal with on a day-to-day basis. Class B extinguishers put out gasoline, oil and other fires from flammable liquids. Depending on how big the garage is, you might need to place several of these throughout the shop.

Class C

Class C extinguishers are meant for electrical fires from wiring or equipment that is run off of electricity. Even if all the motorized tools in the shop ran off of hydraulics or some other power, a class C extinguisher is necessary for fires that start in electrical outlets in office areas, lighting or other electric sources.

Class D

Class D extinguishers are for certain metals that can catch fire and are not often needed in an auto shop. These extinguishers typically put out fires for less common materials, such as titanium or sodium. However, if a shop is working with things such as break pads with magnesium, then this extinguisher is necessary; there is no other way to put out one of these fires.


Combination extinguishers might be an alternative for the auto shop. There are several extinguishers that combine certain class types, although class D cannot be combined. Look for AB, BC or even ABC extinguishers to cover more of the shop with less confusion over which to use. BC extinguishers are a good choice in the shop area.

Why Is Carbon Dioxide Used in Fire Extinguishers?
by Roger Tunsley

Carbon dioxide, otherwise known by its chemical shorthand CO2, is a naturally occurring gas that's present in the air we breathe. This gas is essential to life on earth: It's a vital component of both photosynthesis and cellular respiration.

Among its many uses, CO2 has the ability to put out flames and is therefore used as the extinguishing agent in both portable and fixed-installation fire extinguishers. An examination of its properties and uses shows why it's a popular choice for suppression of most, but not all, types of fire.
 Properties of Carbon Dioxide

CO2 is a colorless and, in normal concentrations, odorless gas, advises the MSDS HyperGlossary. It doesn't react with burning materials, so it doesn't create any toxic or other by-products when used to suppress a fire. It's, therefore, a clean gas, meaning it leaves no trace of its use when suppressing a fire.

Carbon dioxide doesn't conduct electricity, making it an ideal fire suppressant for use in computer rooms, electrical distribution stations and other locations where a large amount of electricity may be present.

CO2 acts on fires in two ways: The release of the gas under pressure has a cooling effect, as can be seen by the resulting mist cloud and ice particles; the gas also displaces the oxygen that's necessary to maintain combustion.
Classes of Fire

Fires are classified by the type of material that's burning. There's a broad international agreement on fire classifications in Australia, Asia and Europe. American classifications differ, as shown in the following table:

  • General combustible material such as wood and paper: American Class A International Class A
  • Flammable liquids such as gasoline: American Class B International Class B
  • Flammable gases such as propane: American Class B International Class C
  • Electrical fires: American Class C International Class E
  • Combustible metals such as magnesium: American Class D International Class D
  • Cooking oils and fats: American Class K International Class F
 CO2 as a Fire Extinguishant

CO2 is effective on liquid fires, gaseous fires and electrical fires (American classes B and C and International classes B, C and E). The gas is particularly useful for electrical fires as it's non-conductive and leaves no trace after its use (as would be the case for foams or other gases).
However, CO2 is not recommended for general fires, as it's emitted under high pressure; light burning material, such as paper and wood, could get blown around, possibly worsening the situation.

CO2 Fire-Suppression Systems

Fixed CO2 fire-suppression systems are often installed where the risk of fire from burning liquids or gases is high, such as at gas stations. Businesses will install CO2 fire-suppression systems in enclosed areas such as computer rooms or electrical switch rooms. Many ships have these systems installed in their engine rooms.
Health Risks From CO2 Fire Extinguisher

CO2 may have health risks at high concentrations since CO2 can become toxic or even lethal - in an enclosed space that has been subject to fire suppression, the typical resulting concentrations of CO2 of 17 percent or more can cause loss of function, unconsciousness and death within a minute.
Lower concentrations can cause confusion, dizziness, headaches and nausea.
It's important that any enclosed area that has been subject to a CO2 fire-suppression incident is evacuated immediately.

A CO2 fire extinguisher that's discharging will cool quickly, creating a frostbite risk to the operator, who should take care to touch only the handle and the nozzle and avoid the metal parts of the extinguisher.
With Hagerty Insurance
With Hagerty Insurance


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