Fire Extinguisher – Complete Guide for Fire Safety
A fire extinguisher is one of the most essential fire safety devices designed to control or extinguish small fires before they spread and cause serious damage. It is a portable, easy-to-use safety tool that can save lives, protect property, and minimize financial loss when used correctly. Every home, office, commercial building, factory, and industrial facility should have properly installed and maintained fire extinguishers as part of their fire protection system.
The Fire Triangle
This is The Fire Triangle. Actually, It’s a tetrahedron, because there are four elements that must be present for a fire to exist:
Not all fires are the same. Per NFPA 10, burning may be classified into one or more of the following fire classes and your fire protection specialist will select the right fire extinguisher size and agent for the hazard.
Class A Fires
Fires in ordinary combustibles, such as wood, paper, cloth, rubber and many plastics.
Class B Fires
Fires in flammable liquids- such as gasoline, petrolium greases, tars, oils, oil-based paints, solvents and alcohols-or flammable gases, propane and butane. DOES NOT include fires involving cooking oils and grease.
Class C Fires
Fires involving energized electrical equipment, such as computers, servers, motors, transformers and appliances. Remove the power and a Class C fires becomes one of the other classes of fire.
Class D Fires
Fires in combustible metals, such as magnesium, titanium, zirconium, lithium and potassium.
Class E Fires
Fires in cooking oils and greases, such as animal and vegetables fats.
Some types of fire extinguishing agents can be used on more than one class of fire. Others have warnings where it would be dangerous for the operator to use on a particular fire extinguishing agent.
Fire Extinguishers Classes
Wet Chemical Fire Extinguishers
Wet chemical is an agent that extinguishes the fire by removing the heat of the fire triangle and prevents reignition by creating a barrier between the oxygen and fuel elements.
Wet chemical or Class K extinguishers were developed for modern, high efficiency deep fat fryers in commercial cooking operations. Some may also be used on Class A fires in commercial kitchens.
Water Mist Fire Extinguishers
Water mist extinguishers put out fires by taking away the heat element of the fire triangle. They are an alternative to the clean agent extinguishers where contamination is a concern.
Water mist extinguishers are primarily for Class A fires, although they are safe for use on Class C fires as well.
Water and Foam Fire Extinguishers
Water and foam fire extinguishers extinguish the fire by taking away the heat element of the fire triangle. Foam agents also separate the oxygen element from the other elements.
Water extinguishers are for Class A fires only; they should not be used on Class B or C fires. The discharge stream could spread the flammable liquid in a Class B fire or could create a shock hazard on a Class C fire.
Dry Powder Fire Extinguishers
Dry powder extinguishers are similar to dry chemical extinguishers except that they extinguish the fire by separating the fuel from the oxygen element or by removing the heat element of the fire triangle.
Dry powder extinguishers are for Class D or combustible metal fires ONLY. They are ineffective on all other classes of fires.
Carbon Dioxide Fire Extinguishers
Carbon dioxide fire extinguishers extinguish fire by taking away the oxygen element of the fire triangle, and by removing the heat with a very cold discharge.
Carbon dioxide extinguishers can be used on Class B and C fires. They are usually ineffective on Class A fires.
Clean Agent Fire Extinguishers
Halogenated or clean agent extinguishers include the halon agents as well as the newer and less ozone depleting halocarbon agents. They extinguish the fire by interrupting the chemical reaction and/or removing heat from the fire triangle.
Clean agent extinguishers are effective on Class A, B and C fires. Smaller sized handheld extinguishers are not large enough to obtain a 1A rating and may carry only a Class B and C rating.
Cartridge Operated Dry Chemical Fire Extinguishers
Cartridge operated dry chemical fire extinguishers extinguish the fire primarily by interrupting the chemical reaction of the fire triangle.
Like the stored pressure dry chemical extinguishers, the multipurpose dry chemical is effective on Class A, B and C fires. This agent also works by creating a barrier between the oxygen element and the fuel element on Class A fires.
Ordinary dry chemical is for Class B and C fires only. It is important to use the correct extinguisher for the type of fuel! Using the incorrect agent can allow the fire to reignite after apparently being extinguished successfully.
The Rules for Fighting Fires
Just remember the three A’s
ACTIVATE the building alarm system or notify the fire department by calling 911. Or, have someone else do this for you.
ASSIST any persons in immediate danger, or those incapable on their own, to exit the building, without risk to yourself.
ATTEMPT to extinguish the fire ONLY AFTER activating the building alarm system and assisting any persons in immediate danger.
Only Fight a Fire If:
- The fire is small and contained
- You are safe from toxic smoke
- You have a means of escape
- Your instincts tell you it’s OK
How to Use a Fire Extinguisher
When it is time to use the extinguisher on a fire, just remember PASS!
- Pull the pin.
- Aim the nozzle or hose at the base of the fire from the recommended safe distance.
- Squeeze the operating lever to discharge the fire extinguishing agent.
- Sweep the nozzle or hose from side to side until the fire is out starting at the recommended distance.
Fire Extinguisher Inspection and Maintenance
Like any mechanical device, fire extinguishers must be maintained on a regular basis to ensure their proper operation. You, the owner or occupant of the property where the fire extinguishers are located, are responsible for arranging your fire extinguishers’ maintenance.
Fire extinguishers must be inspected or given a “quick check” every 30 days. For most extinguishers, this is a job that you can easily do by locating the extinguishers in your workplace and answering the three questions below.
- Is the extinguisher in the correct location?
- Is it visible and accessible?
- Does the gauge or pressure indicator show the correct pressure?
Fire extinguishers must also be maintained annually in accordance with local, state, and national codes and regulations. This is a thorough examination of the fire extinguisher’s mechanical parts, fire extinguishing agent and the expellant gas.
Your fire equipment professional is the ideal person to perform the annual maintenance because they have the appropriate servicing manuals, tools, recharge materials, parts, lubricants, and the necessary training and experience.