VOLUMETRIC AND MASS FLOW CONTROL OF FLUIDS UTILIZING A VARIABLE PRESSURE RESTRICTION WITH A MECHANICAL DIFFERENTIAL PRESSURE BALANCING LOOP

摘要

Traditional pressure based mass and volumetric flow meters/controllers calculate a flow rate by measuring the upstream pressure, pressure differential, and fluid temperature across some type of flow restriction. A different concept of pressure based mass flow measurement and control, introduced in this paper, can an employ single absolute pressure and temperature measurement to control liquids and gases with constant outlet process pressure. An intrinsically safe, all mechanical volumetric flow producer maintains the fluid control while sensors in the device acquire temperature, absolute, and differential pressure for mass flow calculation. The device maintains less than 0.5% stability for output and repeatability, 100 msec time responses, and less than 0.004% change in flow per 1-psi change in inlet pressure.