How to Use a Fire Extinguisher Effectively

How to Use a Fire Extinguisher Effectively

Firemen using water from hose for fire fighting at firefight training of insurance group. Firefighter wearing a fire suit for safety under the danger case.

Master the art of using a fire extinguisher with our comprehensive guide. Discover key techniques and safety tips to handle fire emergencies confidently. Explore the various classes of fires and their unique characteristics. Enhance your fire safety knowledge and preparedness with our comprehensive guide.

Types of Fire: The origin of fire is the combination of combustible material, oxygen, and heat. Fire accidents can be prevented if the cause of fire is identified and proper preventive strategies or measures are adopted.

According to the BS4547 code, fires are mainly divided into five categories depending on the source of fire and the type of combustible material. For example:

  • Class ‘A’ Fire: Fire involving ordinary combustibles.
  • Class ‘B’ Fire: Fire involving petroleum-like material.
  • Class ‘C’ Fire: Gaseous fire.
  • Class ‘D’ Fire: Metal fire.
  • Class ‘E’ Fire: Electrical equipment fire.

Class A Fire: A fire caused by common combustible materials such as wood, cardboard, cloth, paper, cotton, bamboo, rubber, etc., is called a Class A Fire. That is, such a fire is created from common combustible materials.

Generally, this type of fire or burning substance must be extinguished by cooling. The best extinguishing medium for this fire is cold water. Depending on the type of burning combustible material, water may be applied as a jet, spray, or fog. Moreover, if necessary, soda acid, foam, or powder can also be used.

Class B Fire: Fires caused by petroleum-like substances, such as petrol, diesel, kerosene, and other flammable substances, are called Class B Fires. The best technique for extinguishing such fires is to completely cover the fire with blankets or foam to cut off the supply of oxygen (O₂) to the combustible material.

Carbon dioxide (CO₂), dry powder, halon, and foam are commonly used to extinguish Class B fires. However, foam is the best and safest way to extinguish this fire.

Note: Water should not be used to extinguish such fires, as it spreads the flames instead of extinguishing them. However, high-pressure water jets through field nozzles may be capable of extinguishing such fires.

Class C Fire: Fires caused by gaseous substances, such as natural gas, LP-Gas (LPG), coal gas, and produced gas, are called Class C Fires. These are mainly caused by leaks from gas bottles, gas cylinders, or gas pins. The correct strategy to extinguish this fire in its initial stage is to stop the gas supply immediately.

Typically, dry powders or vaporizing liquids are used to extinguish such fires. However, the situation needs to be monitored, and appropriate measures taken. If that proves ineffective, this type of fire should be extinguished by using halon gas through skilled workers.

Class D Fire: A Class D Fire is a fire caused by metallic materials, primarily due to friction, electrical accidents, or similar causes. It is not possible to extinguish this fire with an ordinary fire extinguisher. Therefore, skilled workers and special fire-retardant materials or dry powder, sand, ash, etc., are used to extinguish this fire.

Class E Fire: A fire caused by electrical equipment is called a Class E Fire. The sources of such fires include electric motors, generators, switches, and short circuits.

Extinguishing this type of fire requires a non-conductive medium. These fires are typically extinguished with halon gas, carbon dioxide (CO₂), dry powder, or vaporizing liquid

5 Types of Fire Extinguishers and Their Uses

Red fire extinguishers tank in the fire control room for safety and fire prevention.

Five types of fire extinguishers are commonly used to extinguish different classes of fires, namely:

  1. Water-Filled Fire Extinguishers: Soda-Acid Type
  2. Carbon Dioxide Fire Extinguishers
  3. Halon Fire Extinguishers
  4. Dry Powder Fire Extinguishers
  5. Foam Fire Extinguishers

Operation of Soda-Acid Type Firefighting Appliance: The body of this type of fire extinguisher is made of mild steel and is round and cylindrical in shape. It contains a glass tube filled with 4 to 6 ounces of concentrated sulfuric acid (H₂SO₄), as well as a mixture of 2 gallons of water and 1.2 ounces of sodium bicarbonate (NaHCO₃) chemical powder, filled to a specified volume. The specified filling level is 2/3 of the cylinder’s capacity.

When the operating knob of the device is struck or pressed to extinguish a fire, the glass tube containing sulfuric acid breaks and mixes with the sodium bicarbonate (NaHCO₃) powder and water mixture in the cylinder, producing carbon dioxide (CO₂) gas immediately. Under the pressure of this CO₂ gas, the water mixed with sodium bicarbonate is forced out at high velocity through the discharge pipe or nozzle and directed toward the fire. The fire is extinguished by moving the discharge nozzle in different directions as needed. However, the use of such fire extinguishers is currently very low.

Note: Carbon dioxide (CO₂) is commonly used to extinguish fires, but in this case, the fire is actually extinguished with water. The CO₂ gas produced is simply a byproduct and does not directly act on the fire.

Operation of Carbon Dioxide Fire Extinguisher: This type of fire extinguisher is usually used to extinguish Class B fires, including those involving electrical and liquid combustibles. The unique feature of carbon dioxide (CO₂) extinguishers is that they do not contaminate or damage surfaces by leaving residue in the discharge area. This is because, as CO₂ is released from the cylinder, it changes from liquid to gas and rapidly spreads, extinguishing the fire.

Currently, carbon dioxide gas (CO₂) is particularly well-regarded as a fire-extinguishing medium, as the frozen CO₂ within the cylinder mixes with air quickly and creates a cooling effect on combustible materials, allowing the fire to be extinguished rapidly.

The body of a carbon dioxide fire extinguisher is cylindrical in shape, equipped with a long funnel-type discharge horn, and is made of solid drawn mild steel. The CO₂ gas is filled at a pressure of 700-750 PSI. When the plunger, lever, or valve attached to the cylinder is opened, the gas is released under pressure through the discharge horn or nozzle and is directed onto the fire, thereby extinguishing it.

Note: Under no circumstances should this type of fire extinguisher be used without a discharge horn. It should also be used quickly or for a short period of time.

Operation of Dry Powder Type Firefighting Appliance: This type of fire extinguisher is similar to a water-filled fire extinguisher; however, its cylinder is filled with dry powder instead of water, making it highly efficient and effective. Fires are extinguished by the dry powder stored in the extinguisher, which is usually released from a gas cartridge or under maintained pressure and directed onto the fire.

This type of fire extinguisher is generally made of mild steel and has a cylindrical shape, with a fan-shaped nozzle as its main feature, operated using a plunger or lever.

Dry powder fire extinguishers are mostly used to extinguish liquid fuel fires. However, they may cause some contamination in the extinguishing area. Special powders are used for Class A and Class D fires.

Note: Two types of powder are used in this type of fire extinguisher, namely:

  • Dry Chemical Powder (for general fire extinguishing)
  • Special Dry Powder (for extinguishing metal fires)

The main ingredient in dry chemical powder is sodium bicarbonate (NaHCO₃). In the United States, potassium bicarbonate (KHCO₃) is also commonly used due to its high effectiveness and quOperation of Halon Fire Extinguisher: In Halon fire extinguishers, a halogenated hydrocarbon gas, known as Halon, is stored in the cylinder for firefighting purposes. The gas is typically stored in liquid form, which vaporizes upon use, hence these are also known as vaporizing liquid fire extinguishers.

Halon fire extinguishers use either CBM (Chlorobromomethane) or BTM (Bromotrifluoromethane). These extinguishers are primarily used for Class B fires involving liquid combustibles. The chemicals used in Halon extinguishers are electrically non-conductive, making them particularly suitable for extinguishing electrical fires safely.

CBM-type fire extinguishers are generally suitable for use in aircraft, electrical machinery, transportation, and industrial facilities. BTM-type extinguishers are used in high-value electronics, engine rooms, power plants, control rooms, and telecommunication centers.

Note: Halon fire extinguishers release significant amounts of smoke and are therefore prohibited in enclosed or confined areas. Additionally, Halon gas adversely affects the ozone (O₃) layer. Due to these environmental concerns, the use of Halon fire extinguishers has been internationally discontinued.

Operation of Foam Type Firefighting Appliance: The body of a foam-type fire extinguisher is made of mild steel and is round and cylindrical in shape. It contains two separate containers: one holds acid salt or acetic powder mixed with water, and the other contains foam salt or alkali mixed with water. A gunmetal or brass plunger/handle is attached to the head of the cylinder.

During a fire or when using the extinguisher, pressing the handle or plunger causes the chemicals in both containers to mix and react rapidly, producing foam and carbon dioxide (CO₂) gas. The pressure from the CO₂ gas forces the foam out through the nozzle and directs it onto the fire, extinguishing it.

Note: When using foam, care should be taken to ensure that the foam is applied to the side of the fire rather than directly on top of it, allowing the foam to build up and smother the flames.

This type of fire extinguisher is generally used for extinguishing fires caused by burning liquid fuels, such as petrol, diesel, or kerosene. It is particularly suitable for fires involving liquid fuels stored in drums or tanks.

10 Key Items for Your Emergency Fire Kit Maintenance:

 

To ensure maximum efficiency and proper use of any firefighting appliance,
proper storage and necessary maintenance are essential. The procedures related
to the proper maintenance of fire extinguishers are outlined below:

1.      Each fire extinguisher should be placed on a stand or attached to a wall at a
different location; all fire extinguishers should not be kept together.

2.      The nozzle of the fire extinguisher should always be kept clean.

3.      The bypass hole of the cap attached to the cylinder head should be kept clean, and
the function of the hose pipe should be checked regularly.

4.      After use, the fire extinguisher (cylinder) should be cleaned with water and refilled
with the fire extinguishing agent. The refill date should be noted on the
cylinder head.

5.      The cylinder body should be checked at regular intervals, approximately every four
years, at a pressure of 20-25 atmospheric pressure.

6.      Soda acid-type fire extinguishers must be re-registered one year from the date of
registration.

7.      Carbon dioxide fire extinguishers used in firefighting should be weighed and tested
annually.

8.      Halon-type fire extinguishers should be checked for functionality at least twice a month.
Halon gas is considered good if a white coating is observed after releasing the
gas.

9.      A small amount of foam should be taken from both the outer and inner containers
of foam-type fire extinguishers at specified intervals and mixed with another sample
to test the effectiveness of the foam.

10.  Above all, ensure that the chemical substances in the foam are handled safely during
refilling. Thoroughly dry the containers and take special care to prevent
chemicals from entering the nose and mouth.