Fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent that can be discharged to extinguish a fire. Generally fire extinguisher consists of Cylindrical Tank, Valve, Carry Handle, Operating Lever, Pull Pin, Tamper Seal, Pressure Gauge, Discharge Hose, Discharge Nozzle, Instruction Label, Monthly inspection tag, Annual inspection tag, Extinguishing Agent and Propellant.
TYPES OF FIRE EXTINGUISHER
On basis of expellant storage:
- Stored- pressure
- Cartridge- operated
Stored Pressure fire Extinguisher:
- In stored pressure units, the expellant is stored in the same chamber as the firefighting agent itself.
- Depending on the agent used, different propellants are used. With dry chemical extinguishers, nitrogen is typically used; water and foam extinguishers typically use air.
- Stored pressure fire extinguishers are the most common type.
Cartridge- operated fire extinguisher:
- Cartridge-operated extinguishers contain the expellant gas in a separate cartridge that is punctured prior to discharge, exposing the propellant to the extinguishing agent.
- This type is not as common, used primarily in areas such as industrial facilities, where they receive higher-than-average use.
TYPES OF FIRE CLASSES
- Class A: freely burning, combustible solid materials such as wood or paper
- Class B: flammable liquid or gas
- Class C: energized electrical fire (energized electrical source serves as the ignitor of a class A or B fire – if electrical source is removed, it is no longer a class C fire)
- Class D: metallic fire (titanium, zirconium, magnesium, sodium)
- Class K: cooking fires – animal or vegetable oils or fats.
ON BASIS OF FIRE EXTINGUISHING AGENT:
1.ABC Powder Fire Extinguisher:
- A powder extinguisher sprays a very fine chemical powder composed most commonly of monoammonium phosphate. This acts to blanket the fire and suffocate it.
- Powder extinguishers are effective for class A, B and C fires, since it is not an electrical conductor and since it can effectively break the chain reaction in a liquid or gas fire, something a water extinguisher cannot do.
2.Carbon Dioxide Fire Extinguisher:
- A carbon dioxide fire extinguisher (CO2) is one of the cleanest types of extinguishers to use as it leaves no residue and requires no cleanup.
- The CO2 extinguisher does exactly that – extinguishes CO2. By doing so, it removes oxygen from the fire, effectively suffocating it of oxygen. It is perfect for use on class B fires that involve flammable liquids and on electrical fires.
3.Wet Chemical Fire Extinguisher:
- The wet chemical extinguisher is a specialized type primarily focused on class K fires, those involving cooking media such as animal and vegetable fats or oils and for Class A fires also.
- These extinguishers contain a solution composed of potassium that effectively launches a two-pronged assault on fires.
- First, the liquid mist it sprays acts to cool the fire. Second, due to the chemical reaction of the solution with the cooking medium, a thick soap-like substance forms, sealing the surface of the liquid to prevent re-ignition.
4.WATER MIST FIRE EXTINGUISHER:
- This type of extinguisher releases microscopic water molecules that fight the fire on a variety of levels.
- First, water is dispersed in microscopic fog-like form, so the level of oxygen in the air is decreased, which helps to suffocate the fire. Second, the water particles are drawn to the fire and, and reduces the temperature.
- Finally, the water has been de-ionized (the minerals have been removed). As a result, it can actually be used on electrical fires, as the de-ionized water will not act as a conductor, as well as on burning liquids/gases that a standard water extinguisher could not be applied to.
- Thus, a water mist extinguisher is safe and effective for use on classes A, B, C and K fires.
5.Foam Fire Extinguisher:
- Foam fire extinguishers are suitable for class A and the flammable liquids of class B, though not effective for gaseous fires.
- They spray a type of foam that expands when it hits the air and blankets the fire. This blanket prevents the vapours from rising off the liquid to feed the fire, thus starving it of fuel. Also, because the foam is mixed with water, it has a cooling effect as well.
- Foam extinguishers are some of the best for liquid fires, such as gasoline fires, but can also be used on Class A fires involving solid combustibles like wood.
6.Clean Agent Fire Extinguisher:
- A clean agent fire extinguisher is a type of gaseous fire suppression. Stored in its liquid form, when it is sprayed and hits the air, it converts to its gas form which is non-conductive, safe for use while humans are present, leaves no residue, and has a very short atmospheric lifetime, making it eco-friendly.
- The gas, often composed of Halon, extinguishes fire by reducing the oxygen levels and impeding the chain reaction. Because it is non-conductive and so clean, it is ideal for rooms or businesses filled with electrical and computer equipment. They are most commonly used for class B and C fires.
HOW TO USE THE FIRE EXTINGUISHER:
Steps to be followed to use fire extinguisher can easily be remembered by the acronym “PASS”.
- Pull (Pin) Pull pin at the top of the extinguisher, breaking the seal.
- Aim – Approach the fire standing at a safe distance.
- Squeeze – Squeeze the handles together to discharge the extinguishing agent inside.