US PATENT SUBCLASS 137 / 517
.~.~ Biased open

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

455  DF  LINE CONDITION CHANGE RESPONSIVE VALVES {11}
511  DF  .~ Direct response valves (i.e., check valve type) {14}
517.~.~ Biased open {3}
518  DF  .~.~.~> Oppositely swinging vanes
519  DF  .~.~.~> Weight biased {2}
521  DF  .~.~.~> Pivoted valves

DEFINITION

Classification: 137/517

(under subclass 511) Valves in which a bias means is provided to maintain the valve normally open against fluid pressure on the valve itself tending to close or partly close the valve. The bias means may be the weight of the valve body itself.

SEE OR SEARCH THIS CLASS, SUBCLASS:

409+, for normally open float valves.

479+, for governor valves biased normally open to control the flow in a combustion engine suction line.

505+, for valves with a separate connected fluid reactor surface in which the bias tends to open the valve.

SEE OR SEARCH CLASS

251, Valves and Valve Actuation, 336+, for biased valves, per se, and see the search notes to subclass 336.