DESIGN DEVELOPMENT AND TESTING OF NON-MODULATING PRESSURE CONTROL VALVES. VOLUME III

Abstract : A pressure regulator was analyzed. The regulator, designed to operate as an on-off device, tended toward proportional pressure control when subjected to certain inlet pressures and flow demands. As an on-off device, the regulator duty cycle was determined by inlet pressure and flow demand. Setting of the pressure dead-band influenced the frequency of limit-cycle operation. For purposes of analysis the regulator was considered as a lumped-parameter device and described mathematically by a linear set of differential equations and constraint equations. The static stability of the regulator (normally unstable for on-off operation) was investigated over the dynamic range of inlet pressures and found to be stable over a very limited region of operation. Although the pressure regulator functioned normally in a limit-cycle mode of closedloop operation, under specific conditions the regulator approached this stable region and performed as a proportional regulator. (Author)