TYPES OF FIRE
There are three major types of fires which are given as under.
Type 1 Fires occurring due burning of ordinary combustible materials such as wood, cloth and paper. Pouring water is the most effective way for extinguishing this kind of fire.
Type 2 Fires occurring due burning of flammable liquids such as oils, petrol, grease and fat. For extinguishing, blanket or smother this kind of fire, thus excluding oxygen, water must never be used.
Type 3 Fires in this category involve live electrical equipment. The extinguishing agent must be non-conducting of electricity and water must not be used for extinguishing this kind of fire.
There are five basic kinds of fire extinguishers commonly used which are discussed as under.
1. Dry Powder Extinguishers
These extinguishers filled with dry powder may be of the gas pressure or stored air pressure type. They are suitable for use on both Type 2 and Type 3 fires.
2. Foam Extinguishers
These are of two main types commonly called mechanical foam and chemical foam type of fire extinguishers. They are effective against Type 2 fires.
3. Carbon Dioxide Type Fire Extinguishers
These are filled with the carbon dioxide. It is operated by means of a plunger, lever trigger or by opening a valve. It is fitted with a distinctively shaped discharge horn. This type of fire extinguisher has only limited effectiveness against Type 1 kind of fires. It is suitable for extinguishing type 2 and 3 kinds of fires.
4. Water Filled Fire Extinguishers
The soda acid kind is the most common kind of water extinguishers. They are most suitable for extinguishing fire for type 1. Such fires are resulting from ordinary combustible materials such as wood cloth and paper.
5. Vaporizing Liquid Type Fire Extinguishers
They may be filled with either carbon tetrachloride (CTC.) or chlorobromethane (CBM) where as CTC kinds of extinguishers may be of the pump, gas cartridge or stored pressure type. And CBM may be either gas cartridge or stored pressure. These extinguishers are most effective against electrical kind of fire (Type 3).
6. Stored Air Pressure Type Extinguishers
In stored air pressure type extinguishers, the container is pressurized with air when the extinguisher is filled. The extinguisher is trigger operated and operation can be stopped at any time by releasing the trigger grip. It is suitable for type 1 kind of fire only.
7. Gas Pressure Type Extinguishers
In gas pressure type extinguishers the water is expelled under pressure provided by carbon dioxide gas released from cartridge filled inside the container. It is suitable for Type 1 kind of fire.
Reference Introduction to basic Manufacturing Processes and Workshop Technology by Rajender Singh.
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