How Fire Extinguisher Work

Fire extinguishers parts consist of tube, pressure gauge, nozle, safety pin, handle and high pressure gas canister at the top inside the tube. The tube filled with water or a smothering material, such as CO2.
When you pull the safety pin and squeeze the handle, the handle pushes on an actuating rod which presses the valve down to open a passage to the nozzle. The compressed gas inside a canister is released, applying a downward pressure on the fire-extinguishing material (water or smothering material). This pushes the material out the nozzle with high amounts of pressure.

Water Extinguishers
Water extinguishers are filled with regular tap water and pressurized with oxygen. The best way to remove heat is to dump water on the fire but, depending on the type of fire, this is not always the best option.

Dry Chemical Extinguishers
Dry chemical extinguishers are filled with either foam or powder, usually sodium bicarbonate (baking soda) or potassium bicarbonate, and pressurized with nitrogen. Baking soda is effective because it decomposes at 158 degrees Fahrenheit and releases carbon dioxide (which smothers oxygen) once it decomposes. Dry chemical extinguishers interrupt the chemical reaction of the fire by coating the fuel with a thin layer of powder or foam, separating the fuel from the surrounding oxygen.
Warning: when used indoors, powder can obscure vision or damage goods and machinery. It is also very messy.

Carbon Dioxide (CO2) extinguishers
CO2 extinguishers contain carbon dioxide, a non-flammable gas, and are highly pressurized. The pressure is so great that it is not uncommon for bits of dry ice to shoot out. CO2 is heavier than oxygen so these extinguishers work by displacing or taking away oxygen from the surrounding area. CO2 is also very cold so it also works by cooling the fuel.
Carbon Dioxide is ideal for fires involving electrical apparatus, and will also extinguish class B liquid fires, but has NO POST FIRE SECURITY and the fire could re-ignite.

How to use fire extinguisher

Before using your fire extinguisher, be sure to read the instructions before it's too late. Although there are many different types of fire extinguishers, all of them operate in a similar manner.

Even though extinguishers come in a number of shapes and sizes, they all operate in a similar manner. Here's an easy acronym for fire extinguisher use:



Pull the pin at the top of the extinguisher that keeps the handle from being accidentally pressed.

Aim the nozzle toward the base of the fire, not the flame

Squeeze the lever slowly. Stand approximately 8 feet away from the fire and squeeze the handle to discharge the extinguisher. If you release the handle, the discharge will stop.When you pull the safety pin and squeeze the lever, the lever pushes on an actuating rod which presses the valve down to open a passage to the nozzle. The compressed gas is released, applying a downward pressure on the fire-extinguishing material. This pushes the material out the nozzle with high amounts of pressure.

Sweep the nozzle back and forth at the base of the fire. After the fire appears to be out, watch it carefully since it may re-ignite!


A typical fire extinguisher contains 10 seconds of extinguishing power. This could be less if it has already been partially discharged.

Once the fire is out, don't walk away! Watch the area for a few minutes in case it re-ignites. Recharge the extinguisher immediately after use.

When we use Fire Extinguisher ?

Fire needs fuel, oxygen and heat in order to burn. In simple terms, fire extinguishers remove one of these elements by applying an agent that either cools the burning fuel, or removes or displaces the surrounding oxygen.

Fire extinguishers are filled with water or a smothering material, such as CO2. By pulling out the safety pin and depressing the lever at the top of the cylinder (the body of the extinguisher), this material is released by high amounts of pressure.

Portable fire extinguishers are valuable for immediate use on small fires. They contain a limited amount of extinguishing material and need to be properly used so that this material is not wasted. For example, when a pan initially catches fire, it may be safe to turn off the burner, place a lid on the pan, and use an extinguisher. By the time the fire has spread, however, these actions will not be adequate. Only trained firefighters can safely extinguish such fires.

Use a fire extinguisher only if:

- You have alerted other occupants and someone has called the fire department;
- The fire is small and contained to a single object, such as a wastebasket;
- You are safe from the toxic smoke produced by the fire;
- You have a means of escape identified and the fire is not between you and the escape route; and
- Your instincts tell you that it is safe to use an extinguisher.
If all of these conditions are not present, you should NOT try to use a fire extinguisher. Alert other occupants, leave the building following your home escape plan, go to the agreed upon meeting place, and call the fire department from a cell phone or a neighbor's home.