US PATENT SUBCLASS 251 / 43
.~.~.~ Main valve biased open by line pressure

Current as of: June, 1999
Click HD for Main Headings
Click for All Classes

Internet Version by PATENTEC © 1999      Terms of Use


251 /   HD   VALVES AND VALVE ACTUATION

12  DF  FLUID ACTUATED OR RETARDED {12}
25  DF  .~ Pilot or servo type motor {8}
33  DF  .~.~ Choked pressure type servo motor {8}
43.~.~.~ Main valve biased open by line pressure {2}
44  DF  .~.~.~.~> Differential reaction surface for line pressure {1}
46  DF  .~.~.~.~> Diaphragm or bellows motor element

DEFINITION

Classification: 251/43

(under subclass 33) Subject matter in which the main valve is subjected to a constantly acting force derived from the pressure of the flow line and tending to open the main valve.

(1) Note. The line pressure tending to open the main valve may act directly on the seat closing element of the valve or may act on a separate pressure surface connected therewith, such as a piston or diaphragm.

(2) Note. The line pressure opening force may be assisted or opposed by other mechanical loading, such as a spring.

SEE OR SEARCH CLASS

137, Fluid Handling,

464, for safety cut-off valves line pressure biased to open position and subclass 467 for fluid opened valves which require resetting.