Fire extinguisher types in safety

Fire extingusher Machinist & Machinisht Grinder.......
What is fire extinguishers ?
Types of fire extinguisher used in our daily life?
How to use fire extinguisher?
Why we use fire extinguisher?

Fire extingusher ITI-machinisT

Fire is the burning of combustible material. A fire in an unwanted place and on an unwanted occasion and in uncontrollable quantity can cause damage or destroy property and materials. Fires injure people, and sometimes, cause loss of life. Hence, every effort must be made to prevent fire. When a fire outbreak is discovered, it must be controlled and extinguished by immediate correct action.

Is it possible to prevent fire? Yes, by eliminating anyone of the three factors that cause fire. 1.Fuel 2.Heat 3.Oxygen

The factors that must be present in combination for a fire to continue to burn are as follows.

Fuel :-    Any substance, liquid, solid, or gas will burn if given oxygen and high enough temperature.

Heat :-   Every fuel will begin to burn at a certain temperature. Solids and liquids give off vapourwhen heated and it is this vapour which ignites. Some liquids give off vapoureven atnormalroomtemperature say 15°C, eg. petrol.

Oxygen :-   Usually it exists in sufficient quantity in air to keep a fire burning.

Fire extingusher Machinist & Machinisht Grinder

EXTINGUISHING OF FIRES 

isolating or removing any of these factors from the combination will extinguish the fire. There are three basic ways of achieving this.

-starving the fire of fuel by removing the fuel in the vicinity of fire.

-Smothering i.e. by isolating the fire from the Supply of oxygen by bianketing it with foam, sand etc,

-Cooling i.e. by using water to lower the temperature.

Classsification of fires and recommended extingusing
Class 'A' Fire – wood,paper,cloth etc solid materials. – most effective i.e.cooling with water.jets of water should be sprayed on the base of the fire and then gradually upwards.
Class 'B' Fire Flammable liquids and liquids solids - Should be smothered. The aim is to cover the entire surface of the burning liquid. This has the effect of cutting off the supply of oxygen to the fire.

Water should never be used on burning liquids.
Foam, dry powder or CO² may be used on this type of fire.

Class 'C' Fire Gas and liquids gas - Extreme caution is necessary in dealing with liquefied gases. There is a risk of explosion and sudden spreading of fire in the entire vicinity. Lf an appliance fed from a cylinder catches fire shut off the supply of gas. The safest course is to raise an alarm and leave the fire to be dealt with by trained personnel.
Dry powder extinguishers are used on this type of fire.

Special powders have now been developed which are capable of controlling and/ or extinguishing this type of fire.

Class 'D'Fire Involving metals - The standard range of fire extinguishing agents is inadequate or dangerous when dealing with metal fires.

Fire on electrical equipment.

Carbon dioxide, dry powder and vapourising

liquid (CTC) extinguishers can be used to deal with fires in electrical equipment. Foam or liquid (e.g. Water) extinguishers must not be used on eIectrical equipment under any circumstances.

TYPES OF FIRE EXTINGUISHER

A fire extinguisher, flame extinguisher or simply extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situation. It is not intended for use on an out off control fire.

Many types offlre extinguishers are availablewith different extinguishing 'agents' to deal with different classes of
Fires.

Water-filled extinguishers

There are two methods of operation.

- Gas cartridge type

- Stored pressure type

With both methods of operatien the discharge can be interrupted as required, conserving the contact and

preventing unnecessary water damage.

Foam extinguishers

These may be of stored pressure or gas cartridge types.
Always check the operating instructions on the extinguisher before use.
Foam extinguishers are most suitable for:

- flammable liquid fires
- running liquid fires
Must not be used where electrical equipment is involved.

Dry powder extinguisher : Extinguishers fitted with dry powder may be of the gas cartridge orstored pressuretype. Appearance and method of operation is the same as that of the water-filled one. The main distinguishing feature isthe fork-shaped nozzle. Powders have been developed to deal with class D fires.

Carbon dioxide (C02)

This type is easily distinguished by the distinctively shaped discharge horn.

Suitable for class B fires Bestsuited where contamination by deposits must be avoided. Not generally effective in open air. Always check the operating instructions on the container before use. Available with different gadgets of operation such as plunger, lever, trigger etc.
1. CO2 is a colorless and, in normal concentrations, odorless gas. It doesn't react with burning materials, so it doesn't create any toxic or other by-products when used to suppress a fire. It's therefore a clean gas, meaning it leaves no trace of its use when suppressing a fire.
2. Carbon dioxide doesn't conduct electricity, making it an ideal fire suppressant for use in computer rooms, electrical distribution stations and other locations where a Large amount of electricity may be present.

3.CO2 acts on fires in two ways: The release of the gas under pressure has a cooling effect, as can be seen by the resulting mist cloud and ice particles; the gas also displaces the oxygen that's necessary to maintain combustion.

These are the reasons behind the uses of the co2 in fire extinguisher.

But the co2 is not directly used in the extinguisher

In the inner part of the extinguisher, the whole container is filled with the strong solution of sodium carbonate. And there is a glass tube in the bottom of the container contains sulfuric acid. The glass tube is broken with a powerful pressure when required. And the solutions are reacted with each other and carbon dioxide is produced. Then the co2 is released through the tiny hole in a very high pressure and extinguishes the fire.

Halon extinguishers : Theses extinguishers may be filled with carbon tetrachloride and bromochiorodifiuoro methene (BCF). They may be of either gas cartridge or stored pressure type.
They are more effective in extinguishing small fires involving pouring liquids. These extinguishers are particularly suitable and safe to use on electrical equipment as the chemicals are electrically non-conductive.
The fumes given off by these extinguishers are dangerous, especially in confined space.

General procedure to be adopted in the event of a fire to be adopted.

- Raise an alarm.
- Turn off all machinery and power (gas and electricity).
- Close the doors and windows, but do not look or bolt them. This will limit the oxygen fed to the fire and prevent its spreading.
- Try to deal with the fire if you can do so safely. Do not risk getting trapped.
- Anybody not involved in fighting the fire should leave calmly using the emergency exits and go to the designated assembly point. Failure to do this may mean that some person is unaccounted for and others may have to put themselves to the trouble of searching for him or her at risk to themselves.