When shutting down a centrifugal pump properly, is it necessary to first close the outlet?
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What are the dangers of stopping directly?
1. It is usually done to prevent the check valve installed at the outlet from failing to close, which could lead to backflow of the medium, reversal of the centrifugal pump, and such backflow of materials could also cause other process accidents； 2. If the outlet valve is not closed when the pump is stopped and there is a sudden power outage, it will cause the check valve to close suddenly in an impulsive manner, which can reduce its functionality or even damage it ； 3. Shutting down the pump without closing the outlet valve constitutes shutting it down under load, which can cause stress on the electrical system and is therefore not advisable. Therefore, before stopping the pump, the outlet valve should be gradually closed to reduce the pump’s load step by step until the pump is stopped.
It should be turned off； Prevent the outlet check valve from failing, which could cause the pump to rotate in the reverse direction ； Since the pump has stopped rotating and thus lacks energy, the backup pump starts operating or there is pressure in the subsequent pipelines, causing the pump to rotate in the reverse direction ； This can easily cause the impeller backing to loosen, damaging the equipment ； It also has an impact on the motor due to the reverse rotation ；
Before shutting down the pump normally, it is necessary to close the outlet valve to prevent the medium from flowing back and impacting the flow-through components of the pump (mainly the impeller), which could cause the impeller nuts to loosen, the impeller to fall off, or other components to get damaged.
In addition to what those experts mentioned, there is also the issue of backflow pressure
The outlet valve must be closed before shutting down the pump normally; that’s what the operating procedures state.
After stopping the pump, the inlet valve must be closed first to prevent backflow of the medium, which could cause accidents or damage to the equipment
In the case of normal shutdown, simply close the pump outlet valve.
Strict regulations require that the outlet valve be closed first, followed by shutting down the pump, in order to prevent the equipment from reversing and causing the rotor to loosen; generally, a check valve should be installed at the pump outlet.
During normal shutdown of a centrifugal pump, it is necessary to first close the outlet valve, stop the motor, and then close the inlet valve. First, close the outlet to prevent the flow direction of the medium after the pump stops, thereby avoiding the pump from reversing, which could lead to the impeller becoming loose or even falling off. For transporting liquid hydrocarbon media, it also prevents the vaporization of the medium inside the pump when the pump is stopped, thereby reducing the time required for exhausting and filling the pump during the next start-up.