Using the wrong type of extinguisher can make the fire worse and is dangerous to the operator. Fire is a combination of oxygen, fuel and heat. This is called a Fire Triangle. Read operator's manual for inspection, installation and maintenance instructions. Rechargeable models MUST be serviced after every use.
Disposable extinguishers are very limited and can be used only once.
Holding the extinguisher with the nozzle pointing away from you, remove the pin, seal or lever release mechanism. This unlocks the operating lever. Always hold the extinguisher vertically, never horizontally. Releasing the level will stop the discharge. Sweep the nozzle from side to side aiming at the base of the fire.