| 摘要 |
A fluid control valve, which allows selective change of the flow rate of fluid through the valve in the face of high temperatures and high pressures without undue wear to the integral downstream sealing seat, includes a body, having a passageway which consists of a first section and a second section, and a ball disposed in the second section of the passageway. The ball is rotatable around a central axis and has a first through hole of one diameter and a second through hole having a minimum diameter which is smaller than the first diameter. A sacrificial annular upstream seat is disposed upstream from the ball and has an internal diameter smaller than both the diameter of the first through hole and the diameter of the first section of the passageway through the body. As a result of the difference in size between the diameter of the first section and the internal diameter of the sacrificial annular seat, a pressure differential is created, causing a reduction in turbulence and detrimental forces on the downstream seat, thereby protecting the downstream seat, which is an integral part of an end cap or end housing, and has an internal diameter larger than the internal diameter of the sacrificial annular upstream seat, from premature wear, erosion and other damage when the flow rate is varied. |
