Arrangements for modifying the way in which the rate of flow varies during the actuation of the valve

Full Title

Lift valves , i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces ( ; diaphragm valves F16K7/00) > Details (details of more general applicability F16K25/00 - F16K51/00) > Arrangements for modifying the way in which the rate of flow varies during the actuation of the valve