Pressure reducing valves require a minimum pressure differential across their ports to operate properly. This differential pressure required by most valves limits the minimum pressure they can obtain and hold accurately. The ABS supplier needed an unusually low pressure of 15 psi — far below the minimum 75 psi they could maintain with their current system.

Aside from its inability to accurately work at pressures down to 15 psi, the testing system was well designed and reliable. We suggested they just add a 65 psi check valve in line after the pressure reducing valve’s outlet to provide an additional pressure drop, thereby reducing the outlet pressure to the needed 15 psi. Such a simple idea, but it did the trick!