Workplace fires and explosions kill hundreds and injure thousands of workers each year. One way to limit the amount of damage due to such fires is to make portable fire extinguishers an important part of your fire prevention program.
When used properly, fire extinguishers can save lives and property by putting out a small fire or controlling a fire until additional help arrives.
Fire is a very rapid chemical reaction between oxygen and a combustible material, which results in the release of heat, light, flames, and smoke.
For a reaction that creates a fire, the following three elements, which are represented by the three sides of the Fire Triangle, must be present at the same time:
The Fire Tetrahedron introduces a fourth component – the uninhibited chain reaction – to the fire triangle. This representation more accurately describes the fire as a chain reaction process. The chain reaction acts as a feedback loop mechanism of heat to produce the gaseous fuel used in the flame. This feedback provides the heat necessary to maintain the fire. The fuel, oxygen and heat join together in a sustained chemical reaction.
Check out this short video on the the elements of fire and explosion.
Portable fire extinguishers apply an extinguishing agent that will either:
When the handle of an extinguisher is compressed, agent is expelled out the nozzle. A fire extinguisher works much like a can of hair spray.
All portable fire extinguishers must be approved by a nationally recognized testing laboratory to verify compliance with applicable standards. Equipment that passes the laboratory's tests are labeled and given an alpha-numeric classification based on the type and size of fire it will extinguish.
Check out this short audio clip by Dan Clark of the theSafetyBrief.com. Fire extinguisher operation is not as easy as point-and-shoot. We explain the types of fires, and the types of extinguishers, and how to use them. What’s burning? Is the source wood, gasoline or electrical? What’s inside the fire extinguisher makes a difference. In this podcast, Dan describes the types of fires, and the various types of fire extinguishers to use on them.
There are basically five different types or classes of fire extinguishers, each of which extinguishes specific types of fire. Newer fire extinguishers use a picture/labeling system to designate which types of fires they are to be used on. Older fire extinguishers are labeled with colored geometrical shapes with letter designations. Both of these types of labels are shown below with the description of the different classes of extinguishers.
Additionally, Class A and Class B fire extinguishers have a numerical rating which is based on tests conducted by Underwriter´s Laboratories that are designed to determine the extinguishing potential for each size and type of extinguisher.
Different types of fire extinguishers are designed to fight different types of fire. The three most common types of fire extinguishers are: air pressurized water, CO2 (carbon dioxide), and dry chemical. The copy below provides information regarding the type of fire and which fire extinguisher should be used.
Dry Chemical extinguishers are usually rated for multiple purpose use. They contain an extinguishing agent and use a compressed, non-flammable gas as a propellant.
Halon extinguishers contain a gas that interrupts the chemical reaction that takes place when fuels burn. These types of extinguishers are often used to protect valuable electrical equipment since they leave no residue to clean up. Halon extinguishers have a limited range, usually 4 to 6 feet. The initial application of Halon should be made at the base of the fire, even after the flames have been extinguished.
Water These extinguishers contain water and compressed gas and should only be used on Class A (ordinary combustibles) fires.
Carbon Dioxide (CO2) extinguishers are most effective on Class B and C (liquids and electrical) fires. Since the gas disperses quickly, these extinguishers are only effective from 3 to 8 feet. The carbon dioxide is stored as a compressed liquid in the extinguisher; as it expands, it cools the surrounding air. The cooling will often cause ice to form around the horn where the gas is expelled from the extinguisher. Since the fire could re-ignite, continue to apply the agent even after the fire appears to be out.
Look at the extinguisher to the right. The classification is:
The letters (A, B, and C) represent the type(s) of fire for which the extinguisher has been approved.
The number in front of the A rating indicates how much water the extinguisher is equal to and represents 1.25 gallons of water for every unit of one. For example, a 4-A rated extinguisher would be equal to five (4 x 1.25) gallons of water.
The number in front of the B rating represents the area in square feet of a class B fire that a non-expert user should be able to extinguish. Using the above example, a non-expert user should be able to put out a flammable liquid fire that is as large as 10 square feet.
Please click here for more information on each type of fire extinguisher.
Even though extinguishers come in a number of shapes and sizes, they all operate in a similar manner. Here's an easy acronym for fire extinguisher use:
Pull the pin at the top of the extinguisher that keeps the handle from being accidentally pressed.
Aim the nozzle toward the base of the fire.
Squeeze the handle to discharge the extinguisher. Position yourself approximately 8 feet away from the fire. If you release the handle, the discharge will stop.
Sweep the nozzle back and forth at the base of the fire. After the fire appears to be out, watch it carefully since it may re-ignite!
Make sure all employees who are expected to use fire extinguishers if a controllable fire occurs are properly training with hands-on practice. There's no OSHA requirement to actually extinguish a fire or discharge a fire extinguisher during training. However, each employee should handle the fire extinguisher and demonstrate they can perform the PASS steps.
Please click on the video below to learn more about the PASS technique: