If you adjust a pilot operated pressure reducing valve and experience no pressure change, what could be the issue?

A pilot-operated pressure reducing valve relies on various components to function effectively and maintain the desired pressure downstream. When no pressure change is noted despite adjustments, it indicates that there may be structural or operational issues preventing the valve from responding correctly.

If the valve is installed backwards, the flow direction could be reversed, preventing the valve from reducing pressure as intended. Hence, the system would not respond to adjustments because it cannot operate under incorrect flow conditions.

Similarly, if the external drain is plugged, it can create a buildup of pressure in the control area of the valve. This blockage stops the pilot diaphragm from sensing the downstream pressure correctly, leading to a lack of pressure modification when adjustments are made.

Lastly, dirt or debris on the check valve seat can obstruct proper sealing and function. The check valve is crucial for the pilot system to maintain pressure, and any obstruction could prevent the valve from opening or closing as needed, thus negating the effect of any adjustments.

Each of these potential issues contributes to the overall malfunctioning of the pressure reducing valve, which is why identifying any one of them—or all together as a possibility—helps in diagnosing why no pressure change is observed.