Fire extinguishers are essential tools for controlling fires in their early stages, but not all extinguishers are created equal. Different extinguishing agents are suited for other types of fires. We’ll break down the various fire extinguishers by type, including their uses, advantages, and limitations.
Water-Based Extinguishers
Water is a common extinguishing agent primarily used for Class A fires (involving ordinary combustible materials like wood, paper, and cloth). There are different variations of water-based extinguishers:
- Standard Water Extinguishers: These are most effective on Class A fires but unsuitable for use in freezing temperatures unless equipped with antifreeze.
- Water Mist Extinguishers: These extinguishers use distilled water discharged as a fine mist to reduce the chance of equipment damage. They are commonly used in environments like operating rooms, museums, and areas with sensitive equipment.
While highly effective against Class A fires, water extinguishers should not be used on Class B (flammable liquids) or Class C (electrical) fires due to the risk of spreading the fire or causing electrocution.
Foam Extinguishers (AFFF and FFFP)
Foam extinguishers, such as Aqueous Film-Forming Foam (AFFF) and Film-Forming Fluoroprotein (FFFP), are rated for Class A and Class B fires. The foam creates a film over flammable liquid fires (Class B), helping prevent re-ignition by sealing the surface. However, these extinguishers are not suitable for use in freezing conditions.
Carbon Dioxide (CO2) Extinguishers
CO2 extinguishers are ideal for Class B (flammable liquids) and Class C (electrical) fires. One of their primary advantages is that they leave no residue, making them ideal for use around sensitive equipment, such as in laboratories and data centers. However, they have a limited range (3-8 feet) and can be less effective in outdoor or windy conditions where the gas can dissipate quickly.
Halogenated Agent Extinguishers
- Halon Extinguishers: Once a popular choice due to their effectiveness in fighting Class A, B, and C fires without leaving residue, Halon extinguishers have mainly been phased out due to their impact on the ozone layer. However, they are still twice as effective as CO2 in some situations.
- Halon Alternative Clean Agents: Newer clean agents mimic Halon’s performance without environmental harm. These extinguishers are effective on Class A, B, and C fires and leave no residue.
Dry Chemical Extinguishers
- Ordinary Dry Chemical: This extinguisher type uses a powder made from sodium bicarbonate or potassium bicarbonate. It’s often used on Class B and Class C fires. It’s effective for controlling small fires in environments like workshops and garages.
- Multipurpose Dry Chemical: This variation contains ammonium phosphate, making it suitable for Class A, B, and C fires. The agent forms a coating on burning materials, cutting off the oxygen supply, but it lacks cooling effects, which limits its effectiveness for deep-seated fires.
Wet Chemical Extinguishers
Wet chemical extinguishers are designed for Class K fires involving cooking oils and fats. These extinguishers discharge a solution that cools the fire and creates a foam blanket to prevent re-ignition. They can also be used for Class A fires but are vital in commercial kitchens.
Dry Powder Extinguishers
Dry powder extinguishers are designed for Class D fires involving combustible metals like magnesium and sodium. They must be applied using specific techniques. The extinguishing agent can be delivered via an extinguisher or manually using a scoop or shovel. These extinguishers are specialized and typically not needed in general environments.
Selecting a suitable fire extinguisher for your environment is crucial to safety. Always ensure the extinguisher is appropriate for the potential fire hazards in your location, and check the extinguisher’s rating to confirm its intended use.