Fire extinguishers: What you need to know from A to K


portable fire extinguisher

What’s a piece of kitchen equipment that  every cook should have handy and know how to use, but hopes to never need?

A fire extinguisher.

There are a few different types of fire extinguishers. Some are meant for specialized situations, others for more general use. All are classified by two criteria: their mechanism of action, and the types of fires they are meant to extinguish. So first we’ll look at how fires themselves are classified.

According to the Fire Equipment Manufacturers’ Association, there are five types of fires, broken down by fuel source:

  • Class A fires are your regular old fires, started by heat hitting a combustible solid material such as wood, cloth, paper, trash, or plastic.
  • Class B fires spark from flammable liquids or gases, like gasoline,paint, butane,and propane.
  • Class C fires involve powered electrical equipment such as appliances, motors, and transformers. When the electrical power is shut off, these fires become one of the other types of fires.
  • Class D fires are a special group of conflagrations caused by combustible metals like sodium, potassium, magnesium, and aluminum.
  • Class K fires (why K? Because K is for Kitchen!) are fueled by cooking oils and grease from animal or vegetable fats.

Some fire extinguishers are useful in putting out more than one type of fire. Others are more specialized and will have warning labels advising of their proper use.

A fire needs four elements: heat, oxygen, a fuel source, and a chemical reaction. Remove any one of those four and you’ve snuffed that fire. That’s what different fire extinguishers do. Some remove heat. Others take away oxygen. Still others are best at interrupting the chemical reaction causing the blaze.

These are the basic types of fire extinguishers:

  • Water and Foam: these fire extinguishers work by removing heat. Foam-based extinguishers also inhibit the fire’s access to oxygen. Water extinguishers are for Class A fires only. They are NOT for use on Class B or Class C fires – spraying a water extinguisher on a fire caused by a flammable liquid could cause the fire to spread, or in the case of a Class C fire, create the risk of electrical shock.
  • Carbon Dioxide: these extinguishers put out fires by taking away the blaze’s source of oxygen. Their very cold discharge also removes heat.
  • Dry Chemical: these multi-purpose extinguishers are effective on Class A, Class B, and Class C fires. They work by interrupting the chemical reaction creating the fire. They’re the most common type of fire extinguisher found in the home. Some ordinary dry chemical fire extinguishers are designed to put out Class B and Class C fires only; always read the warning label and recommendations before deciding on the right fire extinguisher for your needs.
  • Wet Chemical: by removing heat and creating a barrier between the oxygen and fuel sources feeding the fire, wet chemical fire extinguishers are highly effective against Class K fires, specifically the fires caused by modern,high-efficiency deep-fat fryers found in commercial systems. This is the type of fire-suppression system installed beneath the hoods in many restaurants and commercial kitchens. While also effective in fighting Class A fires, wet chemical fire-extinguishing are generally only used in commercial and industrial applications.
  • Halogenated or Clean Agent: these extinguishers interrupt the chemical processes causing the fire. They’re effective versus Class B and Class C fires.
  • Dry Powder: a specialized type of fire extinguisher used only for putting out Class D fires. Similar to dry chemical extinguishers, but  designed only for putting out combustible metal fires. Not for home use.
  • Water Mist: these relatively new fire extinguishers are designed to replace halogenated extinguishers in situations where contamination is a pressing concern. They remove heat and are most effective against Class A fires.
  • Cartridge-Operated Dry Chemical: like their dry chemical cousins,these fire extinguishers work by interrupting the chemical reaction causing the fire. They can be effective against Class A, Class B, and Class C fires, though ordinary cartridge-operated dry chemical fire extinguishers are most effective in staunching Class B and Class C blazes. Again, always reads the warming labels and buy the fire extinguisher best-suited for your situation.

To learn more about fire extinguishers, check out the Fire Equipment Manufacturers’ Association.