Questions about pressure relief valves
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I’ve run into a problem in my design work, and I hope everyone can help me solve it. A chemical plant needed to recover the condensate water generated by the compressors in its tank area; therefore, we designed and installed an Armstrong condensate recovery pump of model PT-312, with an operating pressure of 0.4–0.8 MPa. When the pressure is below 0.4 MPa, the condensate water cannot be pumped out; when it is above 0.8 MPa, the condensate pump does not operate. The pressure source uses the heated steam from the booster. The pressure is 0.8 MPa. Therefore, we added a pressure relief valve, model Y43H-25. But after installation, a problem arose: the pressure of the heating steam was unstable, fluctuating around 0.8 MPa. It can reach up to around 1.1 MPa, and at lower levels it can be around 0.6 MPa. Therefore, when the outlet pressure of the pressure reducing valve is set at 0.4 MPa, the requirement cannot be met when the heating steam pressure is below 0.8 MPa ； When the outlet pressure is set at 0.6 MPa, it happens that when the pressure of the heating steam reaches 0.9 MPa, the pressure behind the valve exceeds 0.8 MPa, causing the pump to stop operating. I’m really confused. Given that such conditions fall within the operating range of a pressure relief valve, why is there not much difference in pressure before and after it? I’m really confused and hope that the more experienced folks here can give me some guidance. My email address is guojianbang@126.com. Thank you in advance; I hope everyone can help me out.
Piston-type pressure relief valves have quite a few problems; sometimes the piston gets stuck. Since Armstrong products are being used anyway, it’s better to use Armstrong’s pressure relief valves as well. A diaphragm-type valve would give better results
Personally, I think pressure relief valves have quite a few issues and are not very reliable. It is recommended to replace the pressure relief valve with a stand-alone control valve, as stand-alone control valves are relatively reliable. If a self-regulating valve is not desired, a safety valve can be installed at the outlet of the pressure reducing valve; this safety valve will release pressure when it exceeds 0.8 MPa.
Thank you both for your guidance; I once again thank you