Multi-stage pump

The multi-stage centrifugal pump is a variation on the "standard" single-stage or single-impeller centrifugal pump. Depending on the pressure/capacity, multi-stage centrifugal pumps all have the same structure: the first impeller (the rightmost impeller in terms of cross-section) has the function of initial suction of the liquid.

Multi-stage pump operation

The outlet of the first impeller in a "standard" single impeller pump would be led directly to the press. In the case of a multi-stage pump, the output is sent to the suction of the second consecutive impeller. As a result, the pressure is increased, the discharge pressure of the first impeller is the suction pressure of the second impeller, this second impeller will generate a pressure increase above this, this process is repeated with each successive impeller.

Very simply put, if a pressure of 3 bar can be achieved per impeller at a certain capacity, the pressure for five impellers, 5 x 3 bar, could be 15 bar if there were no pressure losses. Because this is the case, the pump will see a higher pressure loss with each additional impeller. With sufficient numbers of impellers, at a certain point no real measurable pressure increase will be generated.

Horizontal and vertical versions

Multistage pumps are available in both horizontal and vertical versions.

Also in this type of pump, the pump can be divided into three parts; the bearing bracket, the fluid part and the shaft seal(s).

• The bearing seat;
• The shaft seal;
• Liquid part;