| 摘要 |
A ball valve assembly that is solids-proof, corrosion-resistant, will maintain seals even under large pressure differentials, and can operate from cryogenic levels to high temperature ranges. An annular recess is formed in the valve body adjacent the ball, and an annular valve seat of rigid material is disposed in the recess. Facing surfaces of the valve body defining the recess and the valve seat are shaped to define a region therebetween having a larger volume (and cross-sectional area) at the high pressure side thereof than at the low pressure side thereof with the transition therebetween. A solid elastic material annular body, such as a sponge graphite body, is disposed in the recess to positively elastically engage the surfaces along the transition upon application of high pressure to the high pressure side of the region, to bias the valve seat into tight sealing engagement with the ball. The surfaces may be beveled, with an angle of convergence of about 2 DEG to 20 DEG , may provide one or more right angle step portions, and/or may be provided as two, spaced, regions with an annular stop member disposed between the elastomeric body in each of the two, spaced, regions.
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