Hydrant wrench

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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[edit]

Several tricoise wrenches; the red ones at the top are in vehicles, the yellow in the middle hang at the fire belts, the bottom one is a polycoise.

In France, 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

  • Open GDF standard gas enclosures and EDF standard electrical enclosures (12mm female triangle wrench);
  • Open fire hydrants (15.6mm female triangle);
  • Open doors without knobs, ventilation accesses and closets containing firefighting equipment in some public locations (5×5mm to 8×8mm square female wrenches);
  • Open dry risers (12.5×12.5mm square female wrench);
  • Open bathroom and toilet doors (screwdriver); and
  • Remove nuts and bolts (13, 17 and 19mm six-point wrenches).

In the United States[edit]

Patent drawing of a United States hydrant wrench.[1]
The head of a hydrant wrench.

The shape of a hydrant wrench is sometimes adapted so it can be used as a tool for other purposes, such as:

  • Storz and spanner hose couplings
  • Rocker lug couplings
  • Water meter shutoff valves
  • Gas cock valves
  • Pentagonal nuts
  • Square nuts.

See also[edit]

  • Birdsill Holly, noted for his inventions related to city water system equipment and apparatus for fire protection, like the fire hydrant.


  1. ^ U.S. Patent 8,740,254, "Apparatus and method for protecting Storz fire fighting hose couplings", filed 18 May 2010.