The SAPCV, which monitors and controls the inlet pressure irrespective of variations in outlet pressure and flow rate are called as upstream pressure control valves. These are meant for controlling the inlet pressure at a precise set value or hold the line pressure or back pressure at its inlet and hence, often called as Pressure Holding Valve or Back Pressure Regulating Valves as well.

The U100 Series are Direct Acting Self Actuated Globe Type Medium Pressure Back Pressure Regulating Valves meant to regulate the inlet pressure at the pre-determined set value required for the processes / equipment protection.

As inlet / upstream pressure tend to rise, it pushes the diaphragm up, the stem & soft seat disc also moves up, an opens the port and relief the excessive pressure. As inlet / upstream pressure is compensated the spring force pushes the diaphragm down, the stem & soft seat disc also moves down and port opening closes affecting stoppage of flow.