Not all fires are the same, and it is important to know the difference for fire protection purposes. Because of this, there are five distinct fire classes categorize by the properties and source of the fire. Different classes have different advised extinguishing methods. Qualified fire protection engineers will be able to ensure code compliance for the needs of your building.

Class A

Class A fires are the most common. Common examples of a class A fire are your standard bonfire and trash fires. These fires burn flammable materials with no other fuel source. For example, they burn solid combustible materials like wood, cloth, paper, plastic etc. Douse these fires with water fire protection systems or fire extinguishers.

Class B

Class B fires use a liquid accelerant. For example, petroleum oils, Kerosene, butane, propane, or gasoline are some of your major liquid fuels. Flammable gases such as butane (typical household lighter) or propane (bbq tank) are also common sources for Class B fires. These fires are common in industries that use a lot of lubricants and fuels, such as, the automotive industry. Removing the oxygen from these fires by smothering or chemical/gas reactions is the best way to extinguish these flames.

Class C

Class C fires stem from electrical equipment. We have talked about this in our blog before but worn out or faulty electrical equipment often leads to a Class C fire. These are common but not limited to industries that use large equipment powered by electricity. However, as we have discussed before, electrical fires can come from anything from a refrigerator to an extension cord. To put out an electrical fire, power must be cut, and non-conductive chemical fire protection should be used to put it out.

Class D

Class D fires come from combustible metals. Titanium, magnesium, aluminum, and potassium are a few of such metals. Although it is difficult to ignite these metals, industries that use them should be aware of the dangers and have safety measures in place. These fires should be extinguished with a dry powder agent.

Class K

Class K fires involving cooking oils and other food preparation fluid catching on fire. Sometimes these are included in Class B fires as a liquid accelerant, but they do deserve their own classification. Cooking oils have a high flash point, which is why they should not be left unattended. Do not try and put a grease fire out with water. If possible, turn off the appliance and remove the fire from the heat source. Otherwise, extinguish with wet chemical fire extinguishers. Commercial kitchens also have the option of installing an Ansul Fire Protection System in their kitchens.

Knowing what kind of fire protection you need is not always straightforward. A fire protection system engineer can get you the right system for your business needs. Give Valley Fire Protection & Plumbing a call today to get started on an estimate.

Related Topics: Fire Protection

By: Tom Hartel

I acquired my expertise by directing day-to-day operations of the business for over 20 years. Continuous hard work helped me become a nationally recognized speaker and expert on fire protection, fire sprinklers, special hazards, and plumbing systems. In this blog, I share my knowledge that will hopefully help you make better decisions for your projects.