What Does
Class B Fire Mean?
A Class B fire involves flammable and combustible liquids and gases, such as gasoline, oil, paint, solvents, propane, and butane. In the context of Occupational Health and Safety (OHS), Class B fires are particularly hazardous due to the rapid spread and intense heat associated with burning liquids and gases. These fires are common in industries like automotive, manufacturing, chemical processing, and laboratories where such substances are regularly used or stored.
It is one of the five classes of fires, along with Class A, Class C, Class D, and Class K.
Characteristics of Class B Fires
- Flammable Liquids and Gases: The fire involves liquids or gases that can ignite easily when exposed to an ignition source.
- Rapid Spread: Class B fires can spread quickly across the surface of flammable liquids, making them difficult to control.
- High Heat: These fires generate intense heat, which can lead to secondary fires or explosions if not properly managed.
Safeopedia Explains Class B Fire
Extinguishing Class B Fires
A class B fire does not leave embers or ashes and can be best extinguished by providing a wall between the fuel and the oxygen, a technique known as smothering. The agents that can be used to extinguish a Class B fire are:
- Foam Extinguishers: Foam extinguishers are effective for Class B fires because they create a barrier between the fuel and the air, smothering the fire and preventing re-ignition.
- Carbon Dioxide (CO2) Extinguishers: CO2 extinguishers are also used for Class B fires as they displace oxygen around the fire, suffocating it without leaving residue.
- Dry Chemical Extinguishers: Multipurpose dry chemical extinguishers can be used to break the chemical reaction of the fire, stopping the flames from spreading.
A small class B fire can also be extinguished by multipurpose dry chemical powder or by water mist that can effectively cool the fire. Re-ignition may also occur if the sources of heating the substance (above the ignition temperature) are not removed. One should never use water stream on a class B fire as it helps to spread the fire since these liquids are lighter than the water.
Class B Fires in the Workplace
Flammable liquids and gases should be stored in appropriate, well-ventilated areas, away from ignition sources, and in containers designed to prevent leaks or spills.
Workers should be trained in the safe handling of flammable substances, including proper use of equipment and emergency procedures in case of spills or leaks.
The workplace should be equipped with suitable fire extinguishers (foam, CO2, or dry chemical) near areas where Class B fire hazards are present.
Additional Safety Measures
- Ventilation: Ensure adequate ventilation in areas where flammable liquids and gases are used to prevent the accumulation of vapors that could ignite.
- No Smoking Policies: Enforce strict no-smoking policies in areas where Class B fire hazards exist to reduce the risk of accidental ignition.
Class B fires require prompt and appropriate action to control, as they can quickly escalate into more serious incidents. Proper training, storage practices, and the availability of suitable firefighting equipment are essential components of an effective fire safety strategy in environments where Class B fire hazards are present.