Why is the normal flow rate of a centrifugal pump less than its rated flow rate?
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When selecting a pump, the rated flow rate is generally 1.1 to 1.15 times the normal flow rate. Why was this choice made? If chosen in this way, wouldn’t the flow rate corresponding to the pump’s optimal efficiency point be higher than the normal flow rate? The pump won’t be operating at its optimal efficiency point either, right? Looking forward to answers from the experts!
In my opinion, the pump designed does not take into account losses that occur during actual operation; as a result, the optimal efficiency value determined in the design is higher than normal
Because after the pump operates for a long time, its flow-related components wear out, resulting in a decline in performance; as a result, the performance curve of the old pump changes and becomes different from that of a new pump. At this point, the operating point of the new pump Qbep or its rated point shifts to the left, becoming a normal operating point, while still maintaining sufficient flow rate, head, and efficiency.
The rated flow rate is generally measured in terms of water; since the density of the actual fluid differs from that of water, the flow rate will vary