Problem of excessively long outlet pipe in centrifugal pumps
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The outlet pipeline of the centrifugal pump is too long, with a nozzle at its end that dispenses the fluid into a tank at atmospheric pressure. As a result, when the pump is started for the first time, it takes some time for the process fluid to displace the air and reach the nozzle at the end. The pump takes quite a long time to develop its head – around ten seconds or so. During this period, the pump’s mechanical seal is prone to damage. The total resistance in the pipeline is taken into account in the calculation of the pump’s head, but could it be that the long length of the pipeline is the reason why it takes so long for the pump to develop its head? Is this the cause of the damage to the mechanical seal? I would appreciate it if an expert could analyze this issue. Thank you.
In addition to impurities in the water, there is another important reason for seal burnout: insufficient water supply, which leads to seal burnout.
Is the operating point of the pump close to the designed value? During the time from the pump to the nozzle, there should always be liquid inside the pump. A faulty mechanical seal is likely due to other reasons
How do you proceed with starting a centrifugal pump? Are the outlet valves fully open?
If this pump uses the medium at the pump outlet as the sealing flush medium, an excessive opening of the pump outlet valve before lift is established, along with low pump outlet pressure, may result in a lack of medium for sealing flushing, leading to damage to the mechanical seal. Start the pump and gradually open the outlet valve to ensure that the pump’s outlet pressure remains at normal levels.
Close the outlet first, then start the pump, and slowly open the outlet – is that how it’s done?