How to solve low flow rate and low current in multi-stage centrifugal pumps
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Operation status of this station’s multi-stage centrifugal pump last week: return valve opening at 40%, flow rate of 160 cubic meters, current of 69A. After being shut down for 5 months and restarted, the status was as follows: return valve fully closed, flow rate of 140 cubic meters, current of 61A. No maintenance was carried out on this pump during the period it was shut down, and no changes took place. We seek expert assistance to determine the reasons for the decrease in flow rate and current
This post was last edited by WSRYLONG on 2018-9-19 08:45. Has there been any change in the opening degree of the inlet and outlet valves of the pump and related equipment? Has the outlet pressure changed? What are the rated parameters of the water pump?
The inlet pipeline of the pump does not have sufficient flow capacity, resulting in cavitation after the check valve is closed.
Check whether the clearance of the impeller mouth ring is too large, and whether the impeller is rusted or perforated
Check whether the inlet valve and pipelines are blocked; if the inlet is fine, the pump needs to be disassembled for inspection – there is likely a problem with the impeller
Checking the performance curve in the corresponding manual may help make a judgment
It seems the pipeline resistance is too high, so it’s being adjusted with a return valve. When the check valve is fully closed, the pump reduces the flow rate through the check valve; as a result, the flow rate decreases, the shaft power drops, and the current falls
When the check valve is fully closed, the pump reduces the flow rate through the check valve; as a result, the flow rate decreases, the shaft power drops, and the current falls