Regarding the flow rate issue of centrifugal pumps
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The pump’s outlet pressure is the same as the rated pressure, but the actual flow rate of the pump is lower than the required rated flow rate; the flow rate corresponding to the performance curve meets the rated requirements. What is the reason for this? I’m having issues with the manufacturer; experts, please help analyze this! Thank you! ! !
It mainly depends on the pressure difference between the pump’s inlet and outlet, right, not just the outlet pressure?
One cannot rely solely on the outlet pressure; it is also necessary to consider the properties of the medium and the inlet pressure. It is advisable to check the current as well and calculate the shaft power to determine whether the system is operating within its rated conditions
The test medium may have a different density from that used in normal operation
Import and export pipelines, as well as the medium. Are the inlet and outlet pipes the same diameter as those of the pump? I’ve had clients use pipes that are smaller than the pump’s inlet, and of course the flow rate is reduced as a result. It depends on the actual operating conditions on site. Also, is the performance curve provided by the manufacturer based on experimental values when the medium is clean water, or should I send the actual data to the manufacturer’s technical team for review?:)
1. Can the manufacturer’s performance test data meet the requirements of the rated operating point? If this condition is not met, it means there is a discrepancy between the actual pump provided by the supplier and the hydraulic model given. Supplier’s responsibilities. 2. The diameter of the impeller can be increased to achieve the flow rate at the rated operating point; in this case, the shaft power must be recalculated, which affects the selection of the motor
The performance curve is derived from clean-water experiments; the density of the actual medium is different； There is also the diameter of the inlet and outlet pipes
Addition 3: The actual density of the medium is lower than that of clear water. With a constant pump head and lower density, the outlet pressure is lower at the same flow rate (compared to the performance curve for water); p = mpγH. To achieve the desired pressure gauge reading, reduce the valve opening, thereby decreasing the flow rate
If plain water is used as the medium, it will meet the specifications provided by the manufacturer.~