US PATENT SUBCLASS 137 / 539
.~.~.~.~ Ball valves

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}
528  DF  .~.~ Reciprocating valves {5}
535  DF  .~.~.~ Spring biased {5}
539.~.~.~.~ Ball valves {1}
539.5  DF  .~.~.~.~.~> With follower

DEFINITION

Classification: 137/539

(under subclass 535) Valves in which the moving element is substantially spherical.

SEE OR SEARCH THIS CLASS, SUBCLASS:

247.21, for a ball valve combined with liquid seal means.

449, for float arm operated ball valves.

519.5, for normally open ball valves.