Under what conditions will the inlet of a standby pump experience overpressure?
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As stated below, the standards require that, when a pump is used with another pump, to prevent the dangers caused by backflow, the inlet pressure rating of the pump should be the same as that of the outlet. May I ask: What is the opening status of the inlet and outlet valves of the standby pump under normal conditions? When does backflow cause overpressure at the inlet of the standby pump? Because regulations require the use of double check valves to prevent backflow in pumps that are in use, with these double check valves in place, when could it lead to overpressure in the standby pump? Specification: If a pump of the same model has a backup unit, the following measures should be considered at the pump inlet to prevent hazards caused by backflow. When the pump outlet pressure P is: a) P ≤ 4.0 MPa: the grade of the inlet valve should be the same as that of the outlet valve ； b) P > 4.0 MPa: A cost-effective solution can be chosen based on investment considerations and the condition of the mechanical seal, such as using the same valve grade for the inlet as for the outlet, or adding a safety valve without upgrading the valve grade.
It’s better to avoid word games; looking at the pictures is more straightforward. To prevent liquid from flowing back, check valves need to be installed. It has nothing to do with overpressure. The oil system uses safety valves as pressure relief valves, and it can also be adjusted with manual bypass valves. Describe what’s in the picture.
According to the actual design drawings, most of the reasons are human-caused