Gresham Gas Sampling products

When setting up test rigs it is important for the test engineer to be able to quickly and accurately adjust the settings of the safety relief valves without removing them the system or applying pressure to their associated loading actuator. To address this requirement FOX-VPS produce a detented, laser engraved, micrometer style adjustment conversion for standard Sun relief valves which has a graduated sleeve fixed to the relief valve body and an handwheel pinned to the valve adjustment screw. Each valve has approximately 100 detented positions covering the valve range with settings repeatable to +/- 1 division. These controls can be fitted to any of the relief valves incorporated into FOX-VPS safety manifolds, details of which appear in the Hydraulic Manifold section of this site.

Accurate load limiting of servo controlled asymmetric actuators has been problematic since the servo valve was invented over 50 years ago. Conventional relief valves, whether limiting the individual actuator chamber pressures or the difference between them (cross port), cannot be set to limit the actuator load because the output force is not proportional to the differential pressure across the piston.