A fire needs three things to burn – fuel, oxygen and heat. This is called the fire triangle. Take one of these elements away, and a fire can’t burn. That’s what a fire extinguisher does. By applying an agent that cools the burning fuel it removes heat. It can also move and displace surrounding oxygen.
Fire extinguishers are simple, but effective. Typically, a fire extinguisher is a cylinder containing water or a smothering material. At the top of the cylinder, a smaller cylinder contains compressed gas. A release valve acts as a locking mechanism and prevents this gas from escaping. When you pull the safety pin and squeeze the lever, 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.
There are multiple types of extinguishers. The most common has three primary purposes, and is called an ABC extinguisher. ABC extinguishers are perfect for homes, because they work on multiple substances, like wood, plastics, electronics, and clothing.
There are other extinguisher types on the market.
Water extinguishers are filled with regular tap water and are typically pressurized with air.
Dry chemical extinguishers are filled with either foam or powder, usually sodium bicarbonate (baking soda) or potassium bicarbonate, and pressurized with nitrogen. 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. In effect, they smother the fire.
CO2 extinguishers contain carbon dioxide, a non-flammable gas, and are highly pressurized. The pressure is so great that often 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.
No matter what type of extinguisher you choose to store in your home, make sure to store it in an easy-to-reach place, and it’s in or near your kitchen. The most common place in the home for fire to break out is the kitchen. So storing your extinguisher in a cabinet in the kitchen, or mounted on the wall near the kitchen is a great idea.
Do NOT store your extinguisher above your stove or any other cooking appliance or heat source. Reaching over the fire for the tool you need to put that fire out, isn’t a good dame plan.
Using a fire extinguisher is easy, but there is a method you should use to be successful on your first try. And that method is called P.A.S.S.
P – Pull the Pin
A – Aim the nozzle (or hose) at the base of the fire
S – Squeeze the trigger
S – Sweep the extinguisher side to side
Read More from the California Fire Prevention Organization