The pilot-operated relief valve is another noteworthy component in the concrete pumping system. It looks so small that users are easily to be fooled into thinking it is unimportant. However, the improper functioning of the relief valve often leads to big problems, such as sharp noise, severe vibration, or in extreme cases, the pump failure.
A pilot-operated relief valve that is going bad has several symptoms that will let you know it is in bad condition. When users turn the hand wheel to tighten the pressure adjusting screw, the pressure on the valve seat is not increased or can not reach the pre-determined set value. In another case when the hand wheel is turned to loosen the pressure adjusting screw, the pressure on the valve seat is not decreased but keeps increasing. Other valve problems are listed in the following.
I. The piston or disc of the pilot valve is stuck. As a result, the pressurized oil can not force open the pilot valve seat. This means the pilot valve loses its ability to control the pressure routed to the dome above the main valve.
II. The piston or disc of the main valve is stuck. The result is that the pressurized oil can never push open the main valve, which means the main valve loses its ability to control the pressure of the whole piping system.
Some of the above problems can be avoided if the valve parts have been machined more precisely and the valve assembled with more care.