| 摘要 |
<p>A flapper valve assembly (10) comprises a valve body (12) defining a passageway (18); a flapper (22) secured within the passageway and mounted for rotation within the passageway between an opened and a closed position; and a compressible O-ring (34) provided on the periphery of the flapper so as to contact the wall of the passageway when the flapper is moved to the closed position. In one embodiment the compressible O-ring includes a toroidal helical wound spring disposed within a polymeric sleeve. The valve assembly provides increased control of pressure across a wide dynamic range, improved position resolution, is compatible with an array of chemistries and temperatures and has improved wear.</p> |
