Several aspects and causes of centrifugal pump loss
Centrifugal pump volume loss
The loss caused by pump leakage is called volume loss. The ratio of pump power without volume loss to pump power with volume loss is called pump volume efficiency η v.
Mechanical loss
The loss caused by the friction between the high-speed rotating impeller and the liquid, as well as the mechanical friction between the bearing and the shaft seal is called the mechanical loss. The mechanical efficiency η m is generally zero point nine six reach zero point nine nine.
Hydraulic loss
When the fluid flows through the impeller and pump shell, the change of flow velocity and direction and the existence of reverse pressure gradient cause circulation and vortex, resulting in energy loss, which is called hydraulic loss. The hydraulic efficiency η h of centrifugal pump under rated flow is generally Zero point eight reach Zero point nine.
PS：
1. The main performance parameters indicated on the nameplate of the centrifugal pump are the values measured under the highest efficiency condition with 20 ℃ clean water as the experiment.
2. Understand and master the meaning and use conditions of each curve in the characteristic curve, and pay attention to the range of the highest efficiency area (η = 92% η max) and its use.
thus
The head produced by centrifugal pump at a certain speed has a limited value. The operating point flow and shaft power depend on the condition of the unit system connected to the pump (differential level, pressure and line loss). The head changes with the flow.
