Reasons and countermeasures for the outlet pressure of a centrifugal pump to drop after running for a period of time
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What are the reasons why the outlet pressure of the IS125-100-250 centrifugal pump drops from 0.5MPa to 0.35MPa after running for a period of time? How to deal with it? The water tank is at a high level 3 meters higher than the water inlet of the water pump. At present, the backup pump is stopped and started.
There are many reasons for this. First check the pipeline to see if your inlet filter is clogged. Are there any foreign objects in the pipes? Is there anything at the outlet? Specific to the pump, the biggest impact on pressure is the orifice ring. The wear of the orifice ring has the greatest impact on the outlet pressure. But I estimate that pumping water will not cause such a large pressure drop unless the pump's mouth ring is severely worn due to abnormal operation. So, check the pipeline.
I agree with the view of wear of the orifice ring. The head of a centrifugal pump will not fluctuate so much due to pipeline problems. Let’s check the impeller, mouth ring and booster plate.
If the operation is normal, it is unlikely that the mouth ring is worn. If there is a filter at the inlet, check the filter first.
I think there are several possibilities: the pump is not filled with liquid, there is air in the pipeline, there is leakage in the pump, or there is debris in the pipeline that is blocked, the orifice ring is too worn, and the mechanical seal is not installed properly (I think this should not be the problem, unless it is really installed wrong)
When the cause cannot be found theoretically, the best way is to disassemble the pump and check!
I don’t know how the motor’s current changes. If the motor’s current increases, it means the efficiency decreases. The reason may be internal leakage, mainly due to wear and tear that causes the mouth ring gap to become larger.； If the current fluctuation is large, it may be caused by the inlet flow rate.: Mainly include blockage, low liquid level, high temperature of the inlet medium, etc.
Bleed the pump first, and then check whether the pump is leaking internally.