PRESSURE ACTUATOR DIAPHRAGM CASING WITH AIR PASSAGES

摘要

A control valve pressure actuator (10) of the pressure-to-close type is provided with a housing in which an upper diaphragm casing (14) thereof includes one or more air passage channels (34, 36). Each of the air passage channels facilitates circulation of air above a diaphragm (20) within the pressure actuator (10) at all times, including when the diaphragm (20) is in a fully open position. By permitting the circulation of air above the diaphragm (20) even when in a fully open position, adjacent an inside surface to the top of the upper diaphragm casing (14), there is not a tendency for the diaphragm (20), biased toward the open position by springs (26), to stick to the inside surface of the top of the upper diaphragm casing (14).