In a backpressure regulator, when the spring force exceeds the pressure of the process
fluid, the downward movement of the piston causes the valve to close. In a pressure
regulator, however, when the spring force exceeds the fluid pressure, downward
movement of the piston causes the valve to open. Conversely, when fluid process
pressure exceeds the set force of the spring, it will cause the backpressure regulator to
open, and it will cause the pressure regulator to close. It is also important to know that