The Solution to Pressure Mixing in Pressure Relief Valve
Pressure mixing in adjustable pressure relief valves is not a common problem but is nonetheless a problem. As users, we still need to have a good understanding of it and know the analysis of reasons and solutions.
Why does pressure mixing occur in the process of using an adjustable pressure relief valve?
As the pipe network at the rear end of the pipeline in sanitary pressure relief valve ruptures, close the valve at P1 or overhaul it, pump A in the pump station stops running, causing the water pressure at the rear end of the pipeline in pressure relief valve to become very low or even an empty tube.
When the normal water supply is restored, when the valve at the front end of the pipeline is suddenly opened or pump A in the pump station is opened, the pressure at the front end of the pipeline rapidly increases, and there’s a large pressure difference between the front and rear end of the pipeline in a short period of time.
The pressure relief valve is too busy working, and the pressure at the upper chamber of the valve is very small. The pressure relief valve is forcibly opened under such big pressure, causing the pressure at the front and rear end of the pipeline to be equal, and the valve experiences short-lived failure, that is, pressure mixing.
Solutions:
1. Based on the mechanism of the pressure relief valve, install a safety valve behind the pressure relief valve. When the pressure of the pressure relief valve is above P2, open the safety valve to relieve pressure, ensuring normal water supply pressure.
2. Shorten the time of pressure mixing, making it close to zero.
3. According to the mechanism of the adjustable pressure relief valve, properly increase the diameter of the pilot valve and shorten the time for the upper and lower chambers to reach balance, making it even close to zero.
As practical experience shows, the second solution is the most practical and economical. It can be quickly opened through the drain valve, making the upper chamber pressure bigger than the lower chamber pressure to expedite the recovery of the valve. The time of pressure mixing is basically zero.
