Reasons for insufficient outlet pressure in centrifugal pumps
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I have a question for all the experts here: The 80AY100*2 centrifugal pump has developed a strange issue recently. Under normal conditions, the pressure should be 2.0 MPa. Due to corrosion in the pump, a new impeller, pump shaft, pump casing, pump cover, and other components were installed; in effect, it’s like a new pump head. However, after starting the pump, the pressure was only 1.2 MPa, with no change in pressure when the outlet valve was opened or closed. The influencing factors have been addressed: 1. The filter screen at the pump inlet has been cleaned. 2. The pressure gauge is functioning properly. 3. The check valve at the pump outlet is in good condition. 4. The dimensions of all spare parts are the same as those originally. 5. All gaskets are in order. Are there any other influencing factors?
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The issue should be considered from two aspects: oneself and the manufacturer. First, consider oneself: has the exhaust from the filling pump been properly handled?； Is the pump inlet pressure lower than before? ； Has the back-pressure been reduced? Next is the issue of the manufacturer: send it back to the factory for another test
Regarding the accessories, in particular, check whether the impeller model is correct and what the clearance between the impeller and the pump casing is; if possible, measure it yourself, otherwise turn to the manufacturer directly.
When a new pump is used for the first time, attention must be paid to venting the pump chamber and pipelines.
Original poster, please check whether the noise level of the pump head is too high during operation In the case of cavitation in a centrifugal pump, when the valve is fully open or partially open, the pressure remains unchanged; it is only when the outlet valve is closed to a certain extent or completely closed that the pressure rises, and at this point the noise inside the pump head also decreases.
Could the guide vanes or impeller be installed incorrectly? I remember whether it’s the export side or the import side; it’s different from the previous ones~!
Is this a two-stage centrifugal pump? The outlet pressure is quite high; I’ve never worked with one before so I’m not sure
If the dimensions of the spare parts are exactly the same, corrosion within the pump casing may lead to excessive gaps due to corrosion; furthermore, it is possible to determine whether exhaust is complete by checking for fluctuations in pressure and vibration.
A question to challenge the original poster: \"The pressure at the outlet valve remains unchanged\" – so what exactly is the range of adjustment? From 40% to 45% or from 0 to 100%? Inaccurate descriptions can lead everyone down the wrong path. If it is confirmed that the pressure of the outlet valve remains unchanged despite significant operation, then it is definitely a problem with the pump itself or with the feed. 1. Check whether the pump feed is unobstructed. Apart from disassembling, inspecting, and cleaning the filter, open the inlet valve fully and turn on the outlet backflow to check whether the pump can be filled properly. 2. Disassemble and inspect the pump body.