FIXED VOLUME VALVE SYSTEM

摘要

Embodiments of the present invention provide valves that provide for uniform holdup volume. An embodiment of the present invention provides a valve comprising a valve body (e.g., one or more pieces) that defines a valve chamber having a valve seat, an inlet flow passage, an outlet flow passage and a diaphragm control flow passage intersecting the valve seat. The valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage. The valve further comprises a diaphragm movable towards and away from the valve seat. According to one embodiment of the present invention, the valve seat can have a semi-hemispherical shape to which the diaphragm conforms when a minimum vacuum is applied to the diaphragm control flow passage.