The main parts of a fire extinguisher are five: one or two tanks; a valve assembly; a hose, or a nozzle; an extinguishing agent; a propellant.

• The tanks are made of metal; they contain the extinguishing agent and the propellant. They can be manufactured by extrusion or by calendering, deep drawing and welding. The tank is linked to the valve assembly through a sleeve.

• The valve regulates the extinguishing agent flow. It is composed of a body, a handle to lift the fire extinguisher, a locking pin, a release lever and a dip tube. In stored pressure fire extinguisher we can also find a pressure gauge, or a pressure indicator. The body of the valve is made of stamped brass, molten aluminium or highly resistant technical resins.

• The hose allows to direct the flow of the extinguishing agent. It is a flexible pipe, it can only be found on fire extinguishers that are heavier than 3 Kg.

• The extinguishing agent is a substance that limits the spreading of the fire and allows for its extinction when it comes into contact with it.

• The propellant is a gas whose function is to expel the extinguishing agent from the fire extinguisher.