The head of the water pump at its rated flow rate does not match the values obtained from field tests
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This post was last edited by wang527746 on 2017-4-13 at 10:14. It is a horizontal end-suction pump with a rated flow rate of 300 cubic meters and a head of 70 meters. The factory test results are consistent (the tests were conducted in an open circuit). However, in actual use within a closed circuit, the system’s static pressure is 2 bar. After the pump is started and adjusted to the rated flow rate, the outlet pressure is 7.5 bar while the inlet pressure is 1.5 bar, giving a pressure difference of 6 bar. This results in a head that is 10 meters less than the specified value. I would like to ask everyone for their insights on this issue ?
It’s quite simple – this indicates that you’re not operating the pump under its rated conditions. The head output has decreased by 10 meters, which means the flow rate must be higher than the rated 300 cubic meters per hour. It is recommended to consult the performance curve provided by the manufacturer and also measure the pump’s flow rate. . .
How can it be said that the head is incorrect when there is no flow? ?
Adjust to rated flow rate of 300
You can ask the manufacturer of the pump to see if it’s possible to increase the diameter of the impeller. If it’s possible, it means the impeller might be too small; if not, it indicates that the selected model is a bit too small and lacks sufficient headroom
Your pressure difference is 6 bar, which is equivalent to 0.6 Mpa. To calculate the head required, use the formula 0.6*102 divided by the specific gravity of the medium. You also need to take into account the rotational speed, as Q=300 and H=70 are values obtained at the rated speed; however, the actual speed of the motor will certainly be different from the rated speed.
Measured with a stroboscope; the rotation speed is roughly the same as that indicated on the nameplate.