Is it better to have a pump impeller with a large diameter and low speed, or one with a small diameter and high speed?
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I need to purchase a double-suction pump from three manufacturers. Two of them have basically identical specifications, while the third one has a significantly larger impeller diameter, but a lower rotation speed; however, the motor power is the same (the number of stages differs). I’m not sure which one to choose I would appreciate it if the experts could provide their opinions and analysis. Thank you!
Pumps with high rotational speeds are small, but they have a larger net positive suction head. At low rotational speeds, the net positive suction head is small. It depends on the net positive suction head of your unit. From a cost perspective, pumps with higher rotational speeds are definitely cheaper.
Check whether the NPSHr meets the requirements; if all conditions are satisfied, choose a pump with a smaller impeller diameter, provided that the fluid does not contain abrasive solid particles. No corrosion
Pump selection takes into account energy consumption, flow rate, head, and the medium.
If cost is not a factor, then definitely lower speeds are the better choice. For the same number of hours of operation, a 4-stage system completes half as many cycles as a 2-stage system; therefore, wear and other issues will be less severe, and the lifespan will be longer. Could the energy consumption also be reduced a bit? After all, less work is required for the shaft seals and bearings as well@ foam_ZPTK
The flow rate is the same as the head; what matters is the efficiency of the pump, as it determines energy consumption
The efficiency of the pump is definitely the factor that has the greatest impact on energy consumption. I remember reading that mechanical seals and bearings also contribute significantly to energy use. Therefore, for devices operating at 3000 revolutions per minute compared to those operating at 1500 revolutions per minute, the latter will certainly have lower energy losses in this regard. Does the moderator have any relevant data?
This post was last edited by foam_ZPTK on 2018-7-5 00:05. Pumps with low rotation speeds have larger shaft diameters and relatively larger seal dimensions. The graph shows the frictional power consumption curve for a balanced seal; the horizontal axis represents the pressure difference. The curve on the left corresponds to the seal diameter. In the graph, p = 20 bar, Dw = 70 mm, n = 1000 min–1, and PR = 215 W
Hello, where did the friction power consumption curve you shared come from? Could you please provide it?