Flow rate controller

Abstract

Flow control of a shear-sensitive, i.e. pressure gradient degradable, liquid from a high pressure source to a lower pressure discharge is achieved by controlling the liquid's exposure to a degradation pressure gradient. Two displacement chambers are provided and connected by a control conduit. First and second movable barriers in the first and second chambers respectively contain a separate controlling liquid. A pressure and flow control valve is included in the control conduit. Incoming pressurized controlled shear-sensitive liquid flows into the first displacement chamber to displace the first barrier which displaces controlling liquid through the flow control valve. Shear-sensitive liquid is dispensed at relatively lower pressure from the second chamber in response to movement of the second barrier driven by the controlling fluid coming from the control conduit into the second chamber. The flow of controlled liquid to and from the chambers is selectively reversed to provide for continuous pumping from the high pressure source to the low pressure discharge. Indication of total flow and rate of flow of the controlled liquid through the discharge conduit may also be indicated. The flow control valve is adjusted to establish the pressure drop imposed on the controlling liquid and thereby the pressure drop in the controlled liquid without subjecting the controlled fluid to a degradation pressure gradient.