Volume loss
The loss caused by the leakage of the pump is called the volume loss. The ratio of the pump power to the pump's power when the volume loss is lost is called the pump's volume efficiency η v.
Mechanical loss
The loss of mechanical friction caused by the friction between the high speed rotating impeller and the liquid and the mechanical friction of the bearings and shaft seals is called the mechanical loss. The mechanical efficiency is η M is usually 0.96 to 0.99.
Hydraulic loss
When fluid flows through impeller and pump casing, the change of flow velocity and direction and the existence of inverse pressure gradient cause circulation and vortices, which cause energy loss. This loss is called hydraulic loss. The hydraulic efficiency of the centrifugal pump under the rated flow rate is η h is generally 0.8 to 0.9.
PS:
1. The main performance parameters indicated on the nameplate of the centrifugal pump are the values measured at the highest efficiency under the water of 20 degrees centigrade.
2, understand and master the meaning and use conditions of the curves in the characteristic curve, and pay attention to the range of the highest efficiency zone (η =92%η max) and its use.
Thus
The lift of a centrifugal pump at a certain speed has a limited value. The work flow and shaft power depends on the system connected with the pump condition (load, pressure difference and line loss). The lift is changed with the flow rate.
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