METHOD AND VALVE FOR CONTROLLING FLOW RATE

摘要

PURPOSE:To control the flow rate of a liquid in a soft tube over a wide range, by opposing diaphragms to each other to pinch the soft tube through which the liquid flows and by expanding and compressing the tube depending on the magnitude of the output air pressure of a liquid flow rate controller to increase and decrease the distance between the inside portions of the tube. CONSTITUTION:An electric signal sent out from a flow rate controller 8 is converted into an air signal by an electro-pneumatic converter 9 so that the air flow is supplied to air chambers 6 in a main body 1 through a controlling air supply pipe 5 and an air pipe hole 10. Diaphragms 7 are attached as lids for the air chambers 6 and face each other so that a soft tube 3 through which a liquid flows is pinched on outside portions. The flow rate of the liquid is controlled by varying the force of the diaphragms 7 pinching the soft tube 3 on the outside portions. Since the wall of the tube 3 is displaced double by the expansion and compression of both the diaphragms 7, the tube of larger diameter can be employed.