FLOW RATE CONTROL AND METERING MEANS FOR SHEAR-SENSITIVE LIQUIDS

摘要

In a flow rate control apparatus, pressure of a primary, or controlled, liquid is reduced without application of shear forces thereto. Each of first and second piston and cylinder assemblies has a first port on one side of the piston and a second port on the other side. A secondary fluid path between the two second ports contains a controlling fluid directed through a pressure reducing valve. The rate of flow of the primary fluid from the discharge cylinder is controlled by the rate of flow of the secondary fluid through the pressure reducing valve. A four way valve couples the controlled liquid at relatively high pressure through the first port in a first cylinder, and the controlled liquid is discharged at relatively low pressure from the first port in the second cylinder. The first and second pistons are rigidly connected to assure synchronized motion and accurate metering of the controlled liquid and to provide for driving of both pistons in response to input pressure of the controlled liquid.