(under subclass 272) Apparatus in which the main valve is arranged to be removable, and a supplemental check valve is provided, biased closed by a spring or by fluid pressure and normally held open by a projection on the main valve or its actuator when the main valve is in place.
SEE OR SEARCH THIS CLASS, SUBCLASS:
223+, for inflation stems having a valved extension which comprises means for opening the valve in the main stem.
283+, for hydrants having the valve and valve seat removable.
320+, for devices for tapping a system under pressure, the system having a valve actuated by the separable tapping device or by means carried thereby.
326, for foot valve extraction through a tank. 327+, for systems having means provided for engagement by tools for assembling and disassembling the system.
329.1, and 329.2+, for repair check type valves held inactive except at times of repair.
613+, for distribution systems having serial valves in a single flow line.
