There is two kind of water supply to fire department one is called hydrant which is there on the ground and other is called landing valve which should be there in all the floor where we cant install hydrant. Its a simple valve. The fire department people connect there water hose to that valve to get water to extinguish fire. The normal pressure should be 65 psi.

A pressure reducing valve is used in hose reel system to reduce the pressure at the inlet of the hose reel to the nominal working pressure. When using a landing valve the  operator must take extreme caution.

The relevant part should be opened slightly until the whole run of hose fills with water and then slowly opened further to increase the pressure of discharge to suit the circumstance.