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How to deal with sudden power failure of magnetic gear pump in operation?

Update:30-06-2020
Summary:

In the use process of magnetic gear pump, if the power […]

In the use process of magnetic gear pump, if the power supply is suddenly blocked or suddenly cut off, if there is no correct operation, the equipment itself will form great harm. Pumps and prime movers generally require very small moments of inertia. As a result, the pump will stop quickly and steeply.
At the moment, unless the pipeline is very short, the inertia of the liquid will still make the liquid stop move forward forcefully, while the deceleration stainless steel magnetic gear pump has the same effect as the throttle valve. In some cases, the pressure at the pump outlet or along the pipeline at a certain height may be lower than atmospheric pressure.
The low pressure head which occurs in this movement phase is called descending wave. At this time, because the liquid column is completely separated, the pressure can be low enough to cause vaporization. Therefore, during the departure period, the pipeline will be damaged due to external atmospheric pressure, which has happened many times. When the liquid column is separated and combined from the beginning, its impact pressure may be enough to make the pipeline or pump break.

Closing the valve on the discharge line can only make the condition worse. Therefore, the valve should be operated according to the procedure. Even if the valve is closed at the beginning of reverse flow, it should be closed rarely.
Reverse flow can be controlled by a valve, perhaps by putting air into the outlet or near the outlet to empty the discharge line. If the backflow is not subjected to resistance ratio, the pump will stop, and then reverse acceleration rotation. After discharge, the stainless steel magnetic gear pump will rotate at the same runaway speed corresponding to the useful hydrostatic head reduced due to system collision and loss.
However, when the reverse flow has been formed, the reverse speed may exceed the runaway speed in the steady state and reach a considerable value. Large reverse speed increases with the increase of pump power and specific speed.
The calculation shows that the large reverse speed can exceed 150% of the additional speed. This point should be considered when selecting prime mover, especially when selecting large motor. In the case of backflow, a pressure rise in the discharge line called a rising wave occurs. The large ascending wave usually occurs in the large reverse direction.

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