US PATENT SUBCLASS 137 / 464-- .~.~ Fluid counter-biased or unseated valve

US PATENT SUBCLASS 137 / 464
.~.~ Fluid counter-biased or unseated valve

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

455	DF	LINE CONDITION CHANGE RESPONSIVE VALVES {11}
456	DF	.~ Safety cut-off requiring reset {7}
464		.~.~ Fluid counter-biased or unseated valve {2}
465	DF	.~.~.~> With mechanical stop against reopening
466	DF	.~.~.~> With fluid pressure seating of valve

DEFINITION

Classification: 137/464

(under subclass 456) Apparatus in which the valve is urged or biased, as by gravity or a spring means, toward a closed or cut-off position and this bias is opposed by the fluid pressure within the apparatus, a lowering in the fluid pressure permitting the valve to seat or close, the arrangement being such that the valve does not return to open position on subsequent increase of fluid pressure.

SEE OR SEARCH THIS CLASS, SUBCLASS:

511+, especially subclasses 522 to 543 for direct response valves opened by line flow and biased to closed position, where the valve shifts freely to and from closed position on change of fluid pressure condition.