(under the class definition) Devices in which a single flow line has a plurality of serially associated flow controlling positions which are sequentially closed or opened by a valve unit.
(1) Note. Included herein as such are anti-scoring means wherein one valve seat or head is protected from wire drawing by the control of the flow by a second valve until the first valve is fully opened or closed.
SEE OR SEARCH THIS CLASS, SUBCLASS:
118+, for anti-scoring means where the flow is controlled by a restrictor until the valve is fully opened or closed.
SEE OR SEARCH CLASS
137, Fluid Handling,
625.39, for similar structures which also include dividing and recombining of the flow and subclasses 627.5 and 628+ for sequential actuation of plural valves.
