US PATENT SUBCLASS 166 / 154
.~ Surrounding conduit valve or closure opened by piston

Current as of: June, 1999
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166 /   HD   WELLS

153  DF  PISTONS, FLUID DRIVEN INTO WELL (E.G., CEMENTING PLUGS) {3}
154.~ Surrounding conduit valve or closure opened by piston

DEFINITION

Classification: 166/154

(under subclass 153) Devices in which a valve, closure or restriction means carried by the casing or tubing in which the piston operates is opened or released for opening by engagement of the piston with the means or an element connected thereto.

SEE OR SEARCH THIS CLASS, SUBCLASS:

194, for sleeve valves on conduits opened by dropped ball type plugs.