How Multistage Centrifugal Pumps Work

In this article, we will learn about multistage centrifugal pumps. We'll look at some of the main components of a multistage pump and how they work.

A multistage centrifugal pump is a rotating device that converts kinetic energy into a liquid head. This is one way of defining a centrifugal pump. There are many more, but for us, this is enough. In simple language, you can say that it is a machine used to transport fluids from one place to another. Multistage industrial pumps are used in all facilities such as refineries, oil production platforms, petrochemical plants, power plants, etc. Of course, multistage pumps are also used in other industries such as agriculture, food processing and residential construction as well as water supply.

Here is a cross-sectional view of a multistage centrifugal pump, let's take a look at some of the main components of the pump and some common terms

On the left side of the pump is the suction port of the centrifugal multistage pump, which descends and enters the eye of the impeller. The impeller has a wear ring, and the impeller rotates inside the diffuser.
We have a seal on the left. This is a mechanical seal. Mechanical seals are used to seal the space between the pump shaft and the pump casing. This prevents any leaks. We also have a ball bearing, also known as an anti-friction bearing
The liquid comes in from the suction port, enters the perforations of the impeller, exits through the impeller, and enters each impeller one by one, repeating the same process. Once we get to the final impeller, the liquid is drained and it goes out the top here, out of this drain.

This is the general layout of a multistage centrifugal pump, but now let's talk in more detail about how it works and what happens to a liquid as it flows through the pump.

We suck in the liquid at the inlet and the liquid goes into the eye of the impeller. The impeller rotates, and the impeller itself rotates within a stationary diffuser housing. We can see that around each impeller is a diffuser.
In this particular pump, we have 7 impellers and 7 diffusers. The liquid enters the impeller's orifice and is thrown radially outward into the diffuser housing. Once it enters the diffuser, it changes direction and leaves the diffuser.
The purpose of both the impeller and the diffuser is to reduce speed and increase pressure. Once the liquid comes out of the diffuser, it will be drained into the space in the housing. It will then be fed into the eye of the next impeller. Repeating this process the liquid is thrown radially. It will go through the impeller, through the diffuser, and then again we will get a reduction in speed and an increase in pressure. We repeat this process 7 times, and finally, the liquid will be discharged from the 7th impeller, and then the liquid will leave the pump through the outlet.

Each impeller and diffuser is classified as a stage. Our pump has 7 impellers and 7 diffusers, so it is classified as a 7-stage pump. It is important to realize that at each stage we are increasing the pressure but the flow rate is not changing.

Let's take a look at some of the multi-stage pumps produced by An Pump Machinery

Motor-driven multistage pump

Diesel engine driven multi-stage pump with 4-wheel trailer

Learn more watch the video

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