US PATENT SUBCLASS 137 / 493
.~ Bi-directional flow valves

Current as of: June, 1999
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137 /   HD   FLUID HANDLING

455  DF  LINE CONDITION CHANGE RESPONSIVE VALVES {11}
493.~ Bi-directional flow valves {4}
493.1  DF  .~.~> One head and seat carried by head of another {3}
493.7  DF  .~.~> Axes of ports perpendicular
493.8  DF  .~.~> Axes of ports parallel
493.9  DF  .~.~> Axes of ports co-axial

DEFINITION

Classification: 137/493

(under subclass 455) Apparatus in which a valve means opens in response to excess pressure over a selected maximum and also opens in response to pressure below a selected minimum, usually to admit atmospheric air, or opens in response to a pressure applied to either side of the valve means.

(1) Note. The valve means may comprise a simple valve to relieve both pressure and vacuum or reverse pressure or the combination of both a valve for relieving high pressure and a valve for relieving a vacuum, or pressure on the opposite side.

SEE OR SEARCH THIS CLASS, SUBCLASS:

180, for diverse fluid containing pressure systems having a discriminating and an abnormal pressure responsive liquid outlet.

226, for tire inflation stems and/or chucks having plural pressure responsive valves arranged on a common axis, one opening to admit inflation fluid under pressure and the other opening to relieve excess pressure in the chuck, stem or tire.

458, for safety cut-off valves requiring reset which are responsive to both high and low pressures or velocities. 512+, for other plural direct response valves, especially subclass 513 for those mechanically interconnected.