Class A extinguisher are for ordinary combustible materials such as paper, wood, cardboard, and most plastics. Thenumerical rating on these types of extinguishers indicate the amount of water it holds and the amount of fire it can extinguish.
Class B fires involves flammable or combustible liquids such as gasoline, kerosine, grease and oil. The numerical ratings for class B extinguishers indicates the approximates number of square feet of fire it can extinguish.
Class C fires involve electrical equipment, such as appliances, wiring, circuit breakers and outlets. Never use water to extinguish class C fires- the risk of electrical shock is far too great! Class C extinguishers do not have a numerical rating. The C classification means the extinguishing agent is non-conductive.
Class D fire extinguishers are commonly found in a chemical laboratory. They are for fires that involve
combustible metals, such as magnesium, titanium, and pottassium and sodium. These types of extinguishers also have no numerical rating, nor are they given a rating, nor they given a multi-purpose rating - they are designed for class D fires only.
There are four different types of fire extinguishers in common use (we are excluding fire blankets and Wet Chemical extinguishers). Think carefully before tackling even the smallest of fires. Remember - safety first!
Water removes the heat from the fire triangle and is ideal for class A flammable solids, like wood, paper and fabrics.Beware, it conducts electricity and is dangerous to use on flammable liquids like petrol or solvents.
AFFF is a great multipurpose extinguisher ideal for class A flammable solids and especially effective on class B flammable liduid fires. It works by forming a special film layer over the top of burning liquid, removing the oxygen from the fire triangle and smothers the flames.
Dry powder works by removing the oxygen from the fire triangle and is safe to use on all common types of fire including electrical. They can leave a lot of mess though so are not ideal for us in confined areas.
Carbon Dioxide or CO2 gas is great because it's totally clean and leaves no mess at all. It works by removing the oxygen from the fire and is suitable for class B, flammable liquid and electrical fires.
There is also Wet Chemical which is a special extinguisher designed specially for fires involving deep fat fryers.
Fire extinguisher are an extremely effective item of fire fighting equipment, but only if you know how to use them properly. There really is no substitute for hands-on training, so if your company offers this, leap at the chance.
An easy way to remember what to do when operating a fire extinguisher is to think of the acronym PASS
P - A - S - S
Pull the Pin at the top of the extinguisher. The pin releases a locking mechanism and will allow you to discharge the extinguisher.
Aim the base of the fire, not the flames. This is important - order to put out the fire, you must extinguish the fuel. is far too great! Class C extinguishers do not have a numerical.
Squeeze the lever slowly. This will release the extinguisher agent in the extinguisher. If the handle is released, the discharge will stop.
Sweep from side to side. Using a sweeping motion, move the fire extinguisher back and forth until the fire is completely out. Operate the extinguisher from safe distance, several feet away, and then move towards the fire once it starts to diminish. Be sure to read instructions on your fire extinguisher - different fire extinguishers recommend operating them from different distance.