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 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 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 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 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.