Monitor regulator system provides overpressure protection for jurisdictional accounts with no release of gas like a relief valve would.

A monitor system consists of two regulators in series. The "worker" regulator controls downstream pressure during normal operating conditions. If the "worker" allows the pressure to build up downstream, the "monitor" regulator takes over control by sensing the higher pressure through the pilot control line and keeping the downstream pressure to a safe maximum pressure.

The "worker" regulator is usually set at 8-10 psi and the "monitor" regulator set at 13-15 psi. Because the monitor regulator is sensing the 8-10 psi setting of the operating regulator, it remains wide open due to its 15 psi set pressure. The "monitor" regulator will remain wide open unless the operating regulator looses pressure control and its outlet pressure climbs to 15 psi. The "monitor" regulator will start to function and limit the downstream pressure to 15 psi.