This HSPRB cartridge is designed to be piloted by one or more HSLR relief valves, and can be used to provide multiple pressure settings and/or blocking.

When the cartridge is installed in its cavity, port 1 is connected to port 2. A HSLR pilot relief valve must be connected to via port 4 to the top (spring side) of the spool. The outlet pressure (port 2) is transmitted thru an orifice in the center of the spool and port 4 to the pilot valve. When the outlet pressure exceeds the pilot valve setting, the pressure on the top side of the spool is relieved, and a pressure imbalance exists across the spool. The spool tends to rise in its bore and throttle or shut-off flow between ports 3 and 2. If the pressure in teh secondary system drops below the relief valve setting,the pilot valves re-seats. The spool is again balanced, and the spring forces the spool downward to allow flow from port 3 to 2.

Used with one of more HSLR pilot valves, several repeatable, high hysteresis pressure ranges are available. Alternate orifices sizes and spring forces are available to further control sensitivity and speed of operation.

The cartridge is composed of steel parts, and all operating parts are hardened as required. The cartridge is designed for easy service or field repair.