3D Model Description

Please see our main Centrifugal Pump article for more information.

Video Lessons

3D Model Details
Fully Interactive 3D Model

Yes

Animation Working Function

Yes

Explode/Assembly Animation

No

Annotated

No

Cross Section

No

Quiz

No

Virtual Reality (VR)

Yes

Learning Interface

No

Podcast

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Video

Yes

Augmented Reality (AR)

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Written Content

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Video Transcript
- [Instructor] Hi, John here. In this video we're going to look at a multistage centrifugal pump. We're gonna look at some of the main components of the pump, we're gonna look at how it works, we're gonna look at some of the design factors associated with this type of pump, and then finally, we'll look at some of the common designs that you're likely to see. So before we go too far into the video, let's just do a little spin. Alright, we can see on this side we've got a cross-section of a multistage centrifugal pump. Let's go through some of the main components of the pump and some of the common terminology. On the left side of the pump through this pipe here, this is our suction inlet, and the suction inlet comes down and feeds into the eye of the impeller. The impeller has a wear ring, and on the outside it has a diffuser. This is the diffuser here. The diffuser is stationary, and the impeller rotates within the diffuser. We've got a sealing arrangement on the left. This is a mechanical seal. The mechanical seal is used to seal the space between the pump shaft and the pump casing. This prevents any leakage. We've also got a ball bearing, also referred to as an antifriction bearing, and if we go back we can follow the liquid through the pump. It's gonna come in, go into the eye of the impeller, it discharges through the impeller, out of the diffuser, and then it passes into each impeller one after the other repeating the same process. Once we get to our final impeller, the liquid will be discharged and it will go out of the top here, out of this discharge pipe. So that is the general layout of the multistage centrifugal pump, but let's now talk in more detail about how it works and what happens to the liquid as it flows through the pump. We're drawing the liquid in here and it is going down into the eye of the impeller. Play the animation. We can see the impeller rotating. Now the impeller itself rotates within a stationary diffuser casing. The diffuser is this item here, and we can see that surrounding each impeller is one diffuser. In this particular pump we have five impellers and five diffusers. The liquid enters the eye of the impeller and is then thrown outwards radially into the diffuser casing. Once it goes into the diffuser it is then gonna change direction and pass out of the diffuser. The purpose of the impeller is to reduce the velocity and increase the pressure. The purpose of the diffuser is also to reduce the velocity and increase the pressure. Once the liquid comes out of the diffuser, it is going to be discharged into a space in the casing. You can see it's gonna come out and around here, and then it is gonna be fed into the eye of the next impeller. We can see that we are just entering the eye of the next impeller here. If we push play, we can see the impeller turning, and it will go into the next impeller and the process repeats. The liquid is thrown out radially. It will pass through the impeller, through the diffuser, and again, we will get this reduction in velocity and an increase in pressure. We repeat the process five times, and finally, the liquid will be discharged from the fifth impeller, and the liquid will then exit the pump through this channel here and it will travel upwards and out of the discharge pipe. Each impeller and diffuser are classified as one stage. Our pump has five impellers and five diffusers, therefore it is classified as a five-stage pump. It's important to realize that at each stage we're increasing the pressure, but there is no change in the flow rate. Now we've seen some of the components and we know how it works, let's discuss some of the interesting aspects about this pump. Unlike single-stage centrifugal pumps, multistage centrifugal pumps do not normally utilize multiple volute casings. Installing multiple volute casings one after the other is impractical due to size considerations. Although our example shows ball bearings, typically you're more likely to see some type of thrust bearing in order that the axial movement created by the impellers of the pump can be compensated for. Our pump also has mechanical seals for sealing the wet and dry sides of the pump. Although it's also possible to use floating ring seal or labyrinth seals. Gland packing, also known as compression packing, is rarely used for sealing multistage pumps. There are two main type of multistage pump designs. One is the barrel type and the other is the ring type. The type of pump we're looking at in our example is a barrel type multistage pump. Barrel type multistage pumps are typically used for high temperature and high pressure applications. Ring section multistage pumps are also used for high temperature and high pressure applications, although there are some differences between the two designs. The barrel type pump allows for the internals of the pump to be removed without disconnecting the outer casing and much of the associated piping. The ring section design allows for more stages to be added or removed, although when maintaining the pump, the external casing and piping must be removed, and this can be considerably more work compared to the barrel type pump where only the internals need to be removed and the outer casing and piping can remain in situ. This video is part of an introduction to centrifugal pumps video course. If you liked this video then check the video description area where you can find a special discount link, and if you click on that link you'll be able to purchase the entire course at a discount price. If you liked this video, please do share it or like it on social media. It really does help us out and allows us to produce more and more content. Thanks very much for your time.