US PATENT SUBCLASS 251 / 30.02
.~.~.~ Main valve biased closed by fluid pressure

Current as of: June, 1999
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251 /   HD   VALVES AND VALVE ACTUATION

12  DF  FLUID ACTUATED OR RETARDED {12}
25  DF  .~ Pilot or servo type motor {8}
30.01  DF  .~.~ Electrically actuated pilot valve {1}
30.02.~.~.~ Main valve biased closed by fluid pressure {2}
30.03  DF  .~.~.~.~> Venting passage within movable main valve {1}
30.05  DF  .~.~.~.~> Fluid pressure sole means for biasing valve closed

DEFINITION

Classification: 251/30.02

Main valve biased closed by fluid pressure:

(under subclass 30.01) Subject matter in which force per unit area exerted by a fluent material is used to maintain the valve in a position which closes a passage to fluid flow until the valve actuator moves for valve to a position which opens the passage.