Fire hydrant, formally called fire hydrant, is a kind of fixed fire-fighting facilities. Its main function is to control combustibles, isolate combustion supporting materials and eliminate ignition sources. It is divided into indoor fire hydrant and outdoor fire hydrant.

The fire protection system includes outdoor fire hydrant system, indoor fire hydrant system, fire extinguisher system, some of which also have automatic sprinkler system, water monitor system, gas fire extinguishing system, fire detection system, water mist system, etc. The fire hydrant set is generally composed of fire box + fire hose + water gun + connector + hydrant + clip, etc. the fire hydrant is mainly used for the fire truck to take water from the municipal water supply network or outdoor fire water supply network to put out the fire, or directly connect the water hose and water gun to put out the fire. Therefore, indoor and outdoor fire hydrant system is also one of the important fire fighting facilities.