US PATENT SUBCLASS 137 / 526
.~.~ Vacuum relief type

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}
526.~.~ Vacuum relief type

DEFINITION

Classification: 137/526

(under subclass 511) Valves which open in response to an excessive decrease in pressure, e.g., to admit atmospheric air.

SEE OR SEARCH THIS CLASS, SUBCLASS:

217, for back-flow prevention by vacuum breaking.

479+, for suction flow governor valves associated with internal combustion engines.

493+, for plural valves, one of which opens in response to

excessive decrease in pressure.