Pump selection
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Parameters of 1 vertical centrifugal multi-stage water pump: flow rate of 4 m3/h, head of 64 meters, motor power of 1.5 kW, rated current of 3.5 A, speed of 2900 revolutions per minute, with 8 stages. Actual operating conditions: The inlet pressure of the water pump is 2.5 kilograms, and the outlet is at a height of 7.5 meters; there is a tower with a pressure of 3 kilograms inside. The inlet pipe has a diameter of DN50, while the outlet pipe has a diameter of DN32. Fault phenomenon: The valve cannot be opened fully while the water pump is running; otherwise, the motor will trip due to overcurrent. Therefore, it can currently only operate with the outlet valve slightly open. Do any of you sea friends have any good suggestions?
The flow rate is too low; slightly opening the valve might already result in a high flow rate. Even if it’s not a fault with the pump itself, it’s still very likely that the system will shut down.
There is no pressure gauge on the outlet; how do you adjust it then?
This post was last edited by CHANGBAISHI on 2018-12-30 08:17. A pressure gauge should be installed at the outlet, or the flow can be controlled to remain within the rated range; the maximum rated current represents the maximum operating capacity. Furthermore, the opening degree of the outlet valve does not indicate whether its operating capacity is normal.
A typical mismatched operating condition, with only a small outlet shut-off valve~~~
The pump’s rated flow rate is 4 m3/h, with a head of 64 meters. Under actual operating conditions, the inlet pressure is 2.5 bar, while the outlet is at a height of 7.5 meters; there is also a pressure of 3 bar inside the tower. The actual head of the pump (calculated in terms of water) = (3 – 2.5) × 10 + 7.5 = 12.5 meters (the 7.5-meter flow resistance is not taken into account). A pump with a rated head of 64 meters actually achieves only a head of 13 meters; thus, the remaining 50-plus meters of head has to be overcome by the outlet valve, otherwise excessive flow will occur and lead to overcurrent. Recommended solution: Replace this multi-stage centrifugal pump with a single-stage cantilever centrifugal pump, choosing one with a capacity of 4 cubic meters per 20 meters~~~~~~~
For an import volume of 2.5 kilograms, at a height of 7.5 meters there is 3 kilograms in the pressure vessel; accounting for a head loss of 10, the head height is 7.5 + 30 + 10 – 25 = 22.5 meters. You can just choose a 25-meter pump.