A pilot operated main relief valve not showing pressure can be due to?

When considering why a pilot-operated main relief valve might not be showing pressure, contamination on the valve seat is a crucial factor. A pilot-operated main relief valve relies on a small pilot pressure to control the larger system pressure. If there is contamination such as dirt, debris, or other obstructions on the valve seat, it can prevent the valve from seating properly or moving as it should. This can result in the valve failing to open or close, which in turn can keep the pressure from rising as expected, leading to the observation that no pressure is shown.

Effective functioning of hydraulic components depends on cleanliness and proper maintenance. Contamination can impede the fluid flow, altering the expected operation of the valve. Regular maintenance and monitoring for contamination are essential practices to ensure hydraulic system components perform effectively. By addressing the problem of contamination, you ensure that the valve can operate correctly and accurately reflect the system pressure.

The other options, while theoretically plausible causes for pressure issues, do not directly contribute to the specific scenario of a pilot-operated valve failing to show pressure in the same immediate and direct way that contamination on the valve seat does. A closed center valve, a closed inlet line, or low fluid levels could cause larger system disturbances, but they are not the most immediate concern