A water pressure regulator is a device that works like an automatic valve to limit higher pressure to a desired constant lower pressure. An in-line pressure regulator contains a hollow cylindrical housing with a centrally-mounted stationary seat near the inlet. Inside is a movable tubular stem (throttling stem or t-stem) surrounded by a spring with a diaphragm attached near the downstream end. The diaphragm and O-rings isolate the spring to keep it dry. Water flows through the inlet, around the seat and through the t-stem. Water pressure acting on the diaphragm forces the spring to compress, pushing the t-stem toward the seat. The closing of the area between the seat and the t-stem reduces the water pressure on the diaphragm. The balance between the force on the diaphragm and spring resistance establishes the outlet pressure. Senninger uses springs with different compressive loads to deliver various preset water pressures from 6 to 60 psi (0.41 to 4.14 bar).
The Senninger PSR Pressure regulator shall maintain the predetermined operating pressure provided that the inlet pressure is at least 5 psi above the expected outlet pressure, but not exceeding the maximum inlet pressure as shown in above.