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 bymeasuring the upstream pressure, pressure differential, and fluid temperature across some type of flowrestriction. A different concept of pressure based mass flow measurement and control, introduced in thispaper, can an employ single absolute pressure and temperature measurement to control liquids and gaseswith constant outlet process pressure. An intrinsically safe, all mechanical volumetric flow producermaintains the fluid control while sensors in the device acquire temperature, absolute, and differentialpressure for mass flow calculation. The device maintains less than 0.5% stability for output andrepeatability, 100 msec time responses, and less than 0.004% change in flow per 1-psi change in inletpressure.