Different Types of Fire Extinguishers Used on Ships

Different types of fire extinguishers are used on ships depending on the type of material acting as fuel. As fires are classified on the basis of the type of fuel which sources them, fire extinguishers are also classified on the same grounds.

 

Portable fire extinguishers are installed at different parts of the ship according to the type of the fire sources present in that area. Portable fire fighter is one of the most convenient and speedy way to fight fire on ships.

Fire extinguishers are mainly classified into five main classes

Class A: These types of fire extinguishers are used in fires which are result of burning of wood, glass fibre, upholstery and furnishing

Class B: These fire fighters are used for fires which occur from liquids such as lubricating oils and fuels

Class C: Fires resulting from involvement of energized electrical equipment such as motors, switches, wiring etc are extinguished by Class C type of fire extinguishers

Class D: Fires occurring as a result of combustible materials such as magnesium and aluminium are extinguished by this type of fire extinguishers

Class E: This type of fire extinguisher is used for subsiding fire resulting from any of the above mentioned materials along with high voltage electricity

 

Type of Portable Fire Extinguishers

Based on the above mentioned classification, portable fire extinguishers are classified and used according to the type of fire.

There are five main types of fire extinguishers used on ships:

1.  Soda Acid Extinguisher

2. Water Extinguisher

3. Foam Extinguisher – Chemical and Mechanical

4. Carbon Dioxide Extinguisher

5. Dry Powder Extinguisher

 

1.  Soda Acid Extinguisher

The soda acid extinguisher is used to fight Class A Fires and can be found in accommodation area of the ship.

Sodium bicarbonate (soda) and sulphuric acid are the prime components of the extinguisher. They combine to form a chemical reaction to produce carbon dioxide gas, which is used to smother the fire.

The arrangement of the extinguishers comprises of a container which holds the sodium bicarbonate solution. A small glass bottle (phial) containing sulphuric acid is placed below a plunger mechanism, which is covered by a safety glass along with a screw and cap at the top.

When the plunger is struck hard, the glass bottle breaks, resulting in mixing of acid and soda. A chemical reaction takes place which produces carbon dioxide gas.

The carbon dioxide gas pressurises the space above the liquid (used for extinguishing fire) and forces it out through the internal pipe of the nozzle.

Note: Soda Acid Extinguishers are now banned on ships because of the poisonous effect which the gas can create.

 

2.  Water Extinguisher

To counter the A- Class fire, portable water extinguisher of 9Ltr are used. The outer container is filled with water and fitted with a CO2 Cartridge (inner container) which forces the water out of the container with pressure.

To operate the extinguisher, first the safety pin/clip is released . When pressure is applied on the plunger, the CO2 cartridge ruptures and forces the water out of the extinguisher.

 

3.  Foam Extinguisher – Chemical and Mechanical

Foam extinguishers are used to extinguish Class B fires and are located near flammable liquids.

Chemical foam – Sodium bicarbonate and aluminium sulphate are the two prime components of this extinguisher.

The main container is filled with sodium bicarbonate, whereas the inner container is filled with aluminium sulphate.

The inner container has a cap at the top which is kept in place by a plunger.

The plunger is turned to release the cap and the extinguisher is then inverted for both the chemicals to mix. Carbon dioxide is produced from the chemical reaction which pressurizes the container from inside and forces out the foam.

Note: Chemical Foam Extinguishers are now banned on ships because of the poisonous effect which the gas can create.

 

Mechanical foam - This extinguisher type also consists of two containers- the outer one is filled with water, whereas the central one has carbon dioxide charge and foam solution.

The central container has a plunger mechanism at the top which when depressed releases the carbon dioxide and allows foam and water to mix.

The foam and water comes out of the nozzle, creating mechanical foam. This extinguisher is operated in upright position.

 

4.  Carbon Dioxide extinguisher

Carbon dioxide extinguishers are mainly used for class B or class C fires. They are not used for accommodation areas and confined spaces because the gas used in lethal. These extinguishers are mainly found in machinery spaces.

Carbon dioxide is stored in liquid form under pressure. A central tube acts as an outlet for the carbon dioxide gas. A plunger attached to a bursting disc at one end and a trigger at the other is used to release the carbon dioxide gas. The liquid changes to gas as it comes out of the extinguisher through a hose.

 

5.  Dry Powder Extinguisher

Sodium bicarbonate powder is used to extinguish almost all types of fires. It is mainly located in engine room and near electrical equipment.

D

Dry powder extinguisher contains sodium bicarbonate powder in the outer container.

A small container with carbon dioxide is placed beneath the plunger mechanism.

When the plunger is pushed, it releases the carbon dioxide gas, which in turn forces the dry powder out of the discharge nozzle.

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Image Credits:

Marine Auxiliary by H.D. McGeorge, menshealth, safetyinfo, safetyinfo