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To understand how to prevent fires, it is important to know how a fire can occur. Four elements must be present at the same time for a fire to take place:
If you remove any of these four elements, the fire will not be able to burn.
Never fight a fire if:
If you are not confident about your ability to handle the situation (even if you are trained in fire fighting), or if you do not have the correct type of fire extinguisher, do not fight the fire. Pull the fire alarm, evacuate the area, and then call the fire department.
Fires are grouped into classes which depend on the material or substance that is present.
To fight the different classes of fires, there are different types of fire extinguishers. Each has its own characteristics, capabilities, and limitations.
Three main types of portable fire extinguishers include:
Water extinguishers: Water extinguishers are filled about two-thirds with water and then pressurized with air. When used for Class A fires, these extinguishers remove the heat from the burning materials.
Carbon Dioxide (CO2) extinguishers: The extinguishing media is pressurized CO2. When used for Class B and C fires, the CO2 covers the fuel by blanketing it, and stops the reaction at the surface by displacing oxygen. Be thorough when using a CO2 extinguisher. It has a moderate spray range and last only 10 to 30 seconds. A hard horn attached to the end of the spray tube helps to contain and aim the spray at the target area.
Dry Chemical extinguishers: Dry chemical extinguishers are the most common and available in few types. These extinguishers will be marked for the classes they are designed to extinguish (e.g., ABC type extinguisher will put out Class A, B and C fires). The extinguishers discharge a blanket of fine powder which creates a break between the fuel and the oxygen in the air. The powder also works to break the chemical reaction. Be accurate when using as they have a short to moderate spray range and last only 10 to 25 seconds.
Be cautious of the residue after using dry chemical extinguishers. The residue can damage motors, computers and other electrical equipment.
Below is a summary of these and other common extinguishers.
|Extinguisher Comparison Table|
|Water||A||Long||60 sec||Fights re-ignition|
|CO2||B and C||Short||10-20 sec||May make breathing difficult in enclosed areas|
|Dry Chemical||B and C |
|Moderate||10-25 sec||Leaves residue|
|Liquid Gas||B and C |
|Short||10 sec||May make breathing difficult in enclosed areas|
|Chemical Foam||A and B||Moderate||10-30 sec||Leaves residue|
|Bucket of Sand / Dry Powder||D||Check with your supervisor regarding equipment for Class D fire fighting|
|Wet Chemical||K||Prevents re-ignition|
Portable fire extinguisher may use the following markings to indicate which class of fire they are designed to fight. These symbols are recommended by the National Fire Protection Association (NFPA) in the USA. The symbols may be shown using colours.
Remember, if you feel that you cannot safely extinguish the fire using the portable extinguisher available and if you have not already done so, pull the fire alarm, evacuate the area, and then call the fire department.
When using an extinguisher, use the PASS system - Pull, Aim, Squeeze, Sweep.
For floor fires, sweep from the edges in. For wall fires, sweep from the bottom up.
As an employer/contractor, you must:
Portable fire extinguishers should be inspected at least monthly. Visually check for the following items. Customize this list for your workplace.
Extinguishers with the following conditions are should be removed from service:
Always check with the supplier or manufacturer if you are not sure about the serviceability of the fire extinguisher.
Depending upon what type of extinguisher it is, a fire extinguisher may be classified as a hazardous product under WHMIS 2015. Many extinguishers will meet the compressed gas criteria and will therefore require a WHMIS label. Other extinguishers may also be classified in other WHMIS classes due to the physical or health effects of the extinguishing media.