Fire extinguisher classes
Fire extinguishers are designed to tackle specific types of fire. Based on this, fire extinguishers are divided into six different classes.
Understanding the fire extinguisher classes is important to understand its use. Ii have highlighted the different fire extinguisher classes, their colour codes and the class of fire they extinguisher.
EXTINGUISHER CLASS OF FIRE COLOUR CODE
Water A RED
Foam A & B CREAM
DCP A, B & C BLUE
CO2 B & C BLACK
Wet Chemical F –
Dry Powder D –
Water fire extinguisher: These fire extinguishers are more effective in fighting class A fire; fire involving solid fuels. There are four different types of water extinguishers: water jet, water spray, water with additives and water mist or fog. Water jet extinguishers work by spraying a jet of water, Water spray extinguishers use a very fine spray of water droplets which is surrounded by air which is non-conductive, Water extinguishers with additives are water extinguishers with foaming chemicals added and Water mist, or fog, extinguishers apply water in the form of mist, or fog, the droplets are much smaller than those from the water spray extinguisher.
Foam fire extinguisher: They are used majorly for class A & B fires. It extinguishes liquid fires by sealing the surface of the liquid, preventing flammable vapour reaching the air and starving the fire of fuel. They are not suitable for free-flowing liquid fires.
Dry Chemical Powder (DCP) fire extinguisher: They are multi-purpose fire extinguishers which can be used for class A, B & C fires. DCP extinguishers can also create a loss of visibility and may create breathing problems. They are not recommended for use by asthmatic patients, as it may trigger asthmatic attack.
CO2 fire extinguishers: CO2 fire extinguishers work on class B and electrical fires. It work by smothering the fire and cutting off the supply of air.
Dry Powder fire extinguisher: It is used on class D fires. It extinguish the fire primarily by interrupting the chemical reaction of the fire triangle.
Wet Chemical fire extinguishers: This is a new agent that extinguishes the fire by removing the heat of the fire triangle and prevents re-ignition by creating a barrier between the oxygen and fuel elements. It is used mainly for class F fires involving Fats.
NOTE: Most available portable fire extinguishers are of the DCP grade, graded A,B,C. So you may not need to choose the type, just to keep it functional and also know how to use it properly.
Keeping the fire extinguisher functional will involve ensuring that the nozzle is not blocked, the pressure gauge is still on GREEN, and shield the fire extinguisher from direct sunlight.