I have a question regarding the start-up and shutdown of a shielded pump
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When starting a canned motor pump, some sources suggest slightly opening the outlet valve, while others recommend keeping it closed at the time of startup. Could you experts please clarify which method is correct for starting the pump? Is there any difference in the startup procedures depending on the model of the canned motor pump?
When starting the pump, the outlet valve should be opened slightly first, and then the inlet valve after it has started running
The purpose is to allow the fluid to exit as quickly as possible, because the bearings in the shielded pump rely on the flow of the medium to dissipate heat; if the medium does not leave the pump body for an extended period, it can easily cause the bearings to burn out
The several experts I consulted today all said that the outlet valve is closed when the machine is started, and this has left me puzzled for a long time as to whether it’s feasible to start the pump in such conditions
We encountered high-power shielded pumps (from Germany); after much trial and error, we managed to start them using the recirculation method. The valves need to be opened to half their flow capacity – with ordinary centrifugal pumps, this is simply not possible, and even some staff at pump manufacturers may not be aware of this.
So don’t rely on superstitions; by thoroughly understanding the principles and characteristics of pumps, you can find appropriate solutions. Relying solely on experience can also lead to situations where it’s not effective
In practice, slightly open the outlet valve; after the motor is activated, the outlet valve will open more easily. Theoretically, the outlet valve is in the closed state
Shielded pumps belong to the category of centrifugal pumps, right? Is the starting current high? As long as the motor current does not exceed the specified value when the outlet valve is fully open, then there should be no problem.
Close the outlet valve and open the minimum return line
Our company first opens the inlet fully, starts the exhaust system, and then gradually opens the outlet.
First, fully open the inlet valve, start after venting, then gradually open the outlet.