US PATENT SUBCLASS 166 / 320
.~.~ Variably opened

Current as of: June, 1999
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166 /   HD   WELLS

316  DF  VALVES, CLOSURES OR CHANGEABLE RESTRICTORS {5}
319  DF  .~ Fluid operated {4}
320.~.~ Variably opened

DEFINITION

Classification: 166/320

(under subclass 319) Devices in which the valve element is adjustable to control the amount of fluid flowing through the valve. The adjustment of the valve may be a positive, variable opening or closing of the valve or it may be an automatic adjustment responsive to fluid pressure at the valve.