Types of Fire Extinguishers

A fire extinguisher is a valuable household item that can help save lives and property in the event of a fire. It is a must-have for any home, and is also required by law in many states. It is important to have the right type of fire extinguisher for the different types of fires, and understand how to operate it correctly in case of an emergency.

The National Fire Protection Agency classifies fires into five categories based on their fuel and the materials they burn. Class A fires consist of ordinary combustible materials such as wood, cloth and paper. Class B fires involve flammable liquids such as gasoline, oil and grease. Class C fires include combustible metals and electrical equipment/fires. Class F fires are a combination of organic solids such as meat and vegetables, and class K fires include cooking fats and oils.

There are two main types of fire extinguishers: handheld and cart-mounted (also known as wheeled). Handheld models range in weight from 0.5 kilograms to 14 kilograms (11.1 to 30.9 lb), and are easily portable by hand. Cart-mounted units weigh more than 23 kilograms (51 lb) and are usually found at construction sites, airport runways, heliports, and marine docks.

Handheld extinguishers can be used on a variety of classes of fires. They can be reloaded and recharged quickly, making them ideal for combating small fires that occur frequently. However, their limited capacity makes them less suitable for larger fires that require greater quantities of extinguishing agent to put out.

Cartridge-operated extinguishers use a cartridge that is filled with an agent such as carbon dioxide or dry chemical powder, or foam water. Upon discharge, the agent is released as a spray or gas that can be directed at the fire and stops its growth by excluding oxygen, cooling it or interrupting its chemical chain reaction. There are several dry agents available in the market, including ordinary sodium potassium bicarbonate (ABC), urea potassium bicarbonate, and potassium chloride (Super-K). A multipurpose extinguisher with an ammonium phosphate base is also available, as well as graphite for class D fires.

These types of extinguishers are not recommended for outdoor use where windy conditions prevail or in locations that are subject to strong air currents, because the agent disperses rapidly. They can also be ineffective when used on a fire that is electric-powered because they conduct electricity and may be dangerous to use near live electrical equipment.

There is a newer type of extinguisher that uses a high-pressure jet of water to stop the fire by soaking it. These extinguishers are not suitable for putting out large flames and must be used within the first 15 seconds of opening, since they lose pressure quickly. This type of fire extinguisher is more efficient than the old-style dry chemicals, but is not as effective as a traditional fire suppression system.

Automatic fire extinguishers are a convenient and cost-effective way to combat fires in remote areas or unmanned spaces, such as generator rooms and computer room cabinets. They work by sensing a rise in temperature, and are designed to spring into action when they sense heat. These extinguishers are also a great option for fighting portable electronic devices such as laptops and computers.