30 CFR § 57.4202
If fire hydrants are part of the mine's firefighting system, the hydrants
shall be provided with--
(a) Uniform fittings or readily available adapters for onsite firefighting
(b) Readily available wrenches or keys to open the valves; and
(c) Readily available adapters capable of connecting hydrant fittings to the
hose equipment of any firefighting organization relied upon by the mine.