Question about water pump flow rate
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Pump model: KQL200/300-37/4(Z)； The flow rate is 280 m3/h, the head is 28 m, and the motor power is 37 kW. The outlet pressure of the pump during actual operation is 1.5 MPa with a current of 55 A. After adjusting the outlet valve, the pressure rises to 2.5 MPa and the current reaches 67 A. What is the approximate flow rate at this point?
Pump model: KQL200/300-37/4(Z)； The flow rate is 280 m3/h, the head is 28 m, and the motor power is 37 kW. The outlet pressure of the pump during actual operation is 0.15 MPa, with a current of 55 A. After adjusting the outlet valve, the pressure rises to 0.25 MPa and the current reaches 67 A. What is the approximate flow rate at this point?
Considering the outlet pressure of the pump during actual operation, which was 1.5 MPa, and the pressure after adjusting the outlet valve, which was 2.5 MPa, it can be seen that the outlet valve is closing. Looking at the current drawn by the pump during actual operation, which was 55 A, and the current after adjusting the outlet valve, which was 67 A, it can be inferred that the outlet valve is opening. Contradictions everywhere, confused? That teacher can clarify things based on the conditions mentioned by the poster.
The pump was selected by the user itself for use with our company’s machinery. I also feel that the head value chosen is too high; however, when the outlet control valve is reduced (with an opening degree of only 25 degrees at this point), the current rises to 67A. The pump manufacturer explained that the difference in head is too large and falls outside the specified range, which results in very low pump efficiency, and that’s why the current cannot increase. When the valve is closed further, the pressure rises and thus the current increases as well. So I’m quite frustrated and would like to ask for advice from all of you experts
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It’s all beyond the pump’s performance curve – and you’re still using it? I’m really impressed
Strange, when the outlet valve is closed to reduce flow, the current should decrease; so how could the value shown by the owner increase?
Is the pressure monitoring point for LZ selected incorrectly? Was it installed behind the outlet valve? :L
Personally, I think that regardless of the pump’s efficiency, reducing the outlet flow rate lowers the power consumption of the pump. If efficiency is indeed low, why does stress increase instead? Unless your motors are equipped with a variable frequency system linked to the flow rate. The flow rate is low, yet the motor is still under load! If it’s not variable frequency, then it might be the outlet back pressure that has changed. The 2 pumps in our plant share a common main pipe; when both pumps are in operation, the back pressure in this main pipe is high, which results in the outlet pressure of each pump being higher than when it is operating alone.