What's the difference between a common hydrant head and a rotary hydrant head?

Summarize the difference: the rotary hydrant means that the connecting base of the hydrant can rotate relative to the bolt body, that is, the hydrant base is equivalent to a movable joint. When installing the fire hydrant, it is only necessary to rotate the base, without rotating the fire hydrant body in the box, thus reducing the distance between the fire hydrant and the back of the box. Ordinary bolts can't rotate and use normally, and the thickness of the box should reach 240mm when installing. The price of rotary fire hydrant is 3-5 times higher than that of ordinary fire hydrant. 3. When replacing, only replace the fire hydrant head, not the others.

Fire hydrant:

Fire hydrant, officially named as fire hydrant, is a fixed fire control facility, whose main function is to control combustible substances, isolate combustion-supporting substances and eliminate fire sources. There are indoor hydrants and outdoor hydrants. Fire fighting systems include outdoor fire hydrant system, indoor fire hydrant system and fire extinguisher system, and some will also have automatic sprinkler system, water cannon system, gas fire extinguishing system, fire detection system and water mist system. Fire hydrant set generally consists of fire box+fire hose+water gun+buckle+bolt+clip.