A hydrant wrench is a tool used to remove fire hydrant caps and open the valve of the hydrant. They are usually adjustable so as to fit different sized hydrant nuts.
In France, the hose and hydrants are linked with Guillemin symmetrical clutch (raccord symétrique Guillemin), which requires the rotation of 1/4 turn of a ring to be fastened. The ring is notched.
The wrench is called "Guillemin wrench" (French: clef Guillemin, pronounced [kle ɡijəmɛ̃]), but the firefighters call it "tricoise wrench" (clef tricoise, [kle tʁikwaz]). The curved part applies on the ring, and the hooked part clutches a notch.
Big tricoise wrenches are placed in fire trucks, and are mainly used to fasten the big hoses, e.g. ∅110 mm hoses to feed the pumper tank from the hydrant (∅100 mm for the clutch). Small tricoise are made of brass and hang at the fire belts; they are used to fasten the small hoses, e.g. ∅70mm to ∅22mm hoses (∅65mm to ∅20mm clutches).
The shape is sometimes adapted so it can be used as a tool for other purposes; it is then called "polycoise wrench" or "Deschamps wrench". These tools are used to
The shape of a hydrant wrench is sometimes adapted so it can be used as a tool for other purposes such as: