| 摘要 |
A control valve pressure actuator of the pressure-to-close type is provided with a housing in which an upper diaphragm casing thereof includes one or more air passage channels. Each of the air passage channels facilitates circulation of air above a diaphragm within the pressure actuator at all times, including when the diaphragm is in a fully open position. By permitting the circulation of air above the diaphragm even when in a fully open position, adjacent an inside surface of the top of the upper diaphragm casing, there is not a tendency for the diaphragm, biased toward the open position by springs, to stick to the inside surface of the top of the upper diaphragm casing.
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