US PATENT SUBCLASS 251 / 197
.~.~.~ Faces pressed by subsequently movable expander

Current as of: June, 1999
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251 /   HD   VALVES AND VALVE ACTUATION

157  DF  WITH MEANS TO INCREASE HEAD AND SEAT CONTACT PRESSURE {8}
193  DF  .~ Gate valve {3}
195  DF  .~.~ Bifaced {4}
197.~.~.~ Faces pressed by subsequently movable expander {2}
198  DF  .~.~.~.~> With second expander
199  DF  .~.~.~.~> Face element directly contacts casing

DEFINITION

Classification: 251/197

(under subclass 195) Devices which are carried by an expander which continues its movement after the face elements have been stopped by contact with the valve body.

SEE OR SEARCH THIS CLASS, SUBCLASS:

204, for similar structures in single-faced gates.