AIR FLOW CONTROL VALVE AND METHOD OF CONSTRUCTING IT

摘要

An air flow control valve, for example for control of air of a ventilating flow in a vertilation system comprises an axially extending valve casing having a venturi-shaped inner face, and an axially movable valve member movable within said valve casing to vary the air flow through the valve. In order that the control movement of the valve member may vary the volume of air flow through the valve according to the same predetermined function regardless of the pressure drop across the valve, or the system in which it is incorporated, the valve casing is shaped to compensate for the variation of the drag coefficient of the valve resulting from movement of the valve member. The invention also comprises a method for determining the required dimensions of a valve casing incorporating such correction.