US PATENT SUBCLASS 137 / 625.37
.~.~.~.~ Piston

Current as of: June, 1999
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137 /   HD   FLUID HANDLING

561 R  DF  SYSTEMS {32}
625  DF  .~ Multi-way valve unit {12}
625.28  DF  .~.~ Dividing into parallel flow paths with recombining {4}
625.33  DF  .~.~.~ Reciprocating {2}
625.37.~.~.~.~ Piston {1}
625.38  DF  .~.~.~.~.~> With internal flow passage {1}

DEFINITION

Classification: 137/625.37

(under subclass 625.33) Subject matter wherein the valve is of the piston type.

SEE OR SEARCH THIS CLASS, SUBCLASS:

538, for line condition change responsive piston valves.

SEE OR SEARCH CLASS

251, Valves and Valve Actuation,

190, for piston valves with means to increase the head and seat contact pressure to reduce wear upon operation.