A fire extinguisher is an active fire protection device used to extinguish or control small fires, in emergency situations. However, they are not effective against large, spreading fires.
The main object of fire safety is to protect life first and property next from the revenge of fire. The objective of fire safety design is the safety of life, protection of property, and continuity of operations. Fire safety planning is required for sites as well as buildings. In industry, it is required for workers and the public. The potentiality of fire is tremendous as it holds the largest range of damaging capacity from a small burn to the disastrous damage of plants, persons, and properties.
Types of fire
Class A –
Class A fires are fires in ordinary combustibles such as wood, paper, cloth, rubber, and many plastics.
Class B –
Class B fires are fires in flammable liquids such as gasoline, petroleum greases, tars, oils, oil-based paints, solvents, alcohols. Class B fires also include flammable gases such as propane and butane. Class B fires do not include fires involving cooking oils and grease.
Class C –
Class C fires are fires involving energized electrical equipment such as computers, servers, motors, transformers, and appliances. Remove the power and the Class C fire becomes one of the other classes of fire.
Class D –
Class D fires are fires in combustible metals such as magnesium, titanium, zirconium, sodium, lithium, and potassium.
Class K –
Class K fires are fires in cooking oils and greases such as animal and vegetable fats.
Types of extinguishers
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.
Water and Foam –
Water and Foam fire extinguishers extinguish the fire by taking away the heating 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.
Carbon Dioxide –
Carbon Dioxide fire extinguishers extinguish the fire by taking away the oxygen element of the fire triangle and also by removing the heat with a very cold discharge. Carbon dioxide can be used on Class B & C fires. They are usually ineffective on Class A fires.
Dry Chemical –
Dry Chemical fire extinguishers extinguish the fire primarily by interrupting the chemical reaction of the fire triangle. Today’s most widely used type of fire extinguisher is the multipurpose dry chemical that 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 & 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 re-ignite after apparently being extinguished successfully.
Wet Chemical –
Wet Chemical is a new agent that extinguishes the fire by removing the heat of the fire triangle and prevents re-ignition by creating a barrier between the oxygen and fuel elements. The wet chemical of Class K extinguishers was developed for modern, high-efficiency deep fat fryers in commercial cooking operations. Some may also be used on Class A fires in commercial kitchens.
Clean Agent –
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.
Dry Powder –
Dry Powder extinguishers are similar to dry chemicals except that they extinguish the fire by separating the fuel from the oxygen element or by removing the heating element of the fire triangle. However, dry powder extinguishers are for Class D or combustible metal fires, only. They are ineffective on all other classes of fires.
Cartridge Operated Dry Chemical –
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 & 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 re-ignite after apparently being extinguished successfully.
Fire blankets are primarily for use on hot oil fires such as frying pans or small deep fat fryers. They can also be used on someone whose clothing has caught fire. They work by smothering the fire, stopping access to the oxygen fuelling it, and extinguishing it.
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.
Only after these two are completed should you ATTEMPT to extinguish the fire.
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
Fire Extinguisher Use
It is important to know the locations and the types of extinguishers in your workplace prior to actually using one. Fire extinguishers can be heavy, so it’s a good idea to practice picking up and holding an extinguisher to get an idea of the weight and feel. Take time to read the operating instructions and warnings found on the fire extinguisher label. Not all fire extinguishers look alike.
Practice releasing the discharge hose or horn and aiming it at the base of an imagined fire. Do not pull the pin or squeeze the lever. This will break the extinguisher seal and cause it to lose pressure.
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.
Starting at the recommended distance, Sweep the nozzle or hose from side to side until the fire is out. Move forward or around the fire area as the fire diminishes. Watch the area in case of re-ignition.