The GEMÜ back pressure valve ensures constant back pressure in process engineering systems. If the inlet pressure rises above a preset value, the diaphragm is raised against the spring force. The valve opens and the excess pressure can escape into the outlet line. If the pressure on the inlet side is reduced, the valve closes as the spring force pushes the diaphragm against the seal seat. The spring force can be adjusted as required using an adjusting screw and secured with the lock nut.