Introduction to Centrifugal Pumps (Mechanical Engineering and HVAC) | SaVRee 3D | Skillshare

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Introduction to Centrifugal Pumps (Mechanical Engineering and HVAC)

teacher avatar SaVRee 3D, Where engineers go to learn.

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Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

Watch this class and thousands more

Get unlimited access to every class
Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

Lessons in This Class

34 Lessons (2h 36m)
    • 1. Centrifugal Pump Landing Page

    • 2. Welcome To The Course

    • 3. Course Overview

    • 4. Centrifugal Pump Components Explained

    • 5. How Centrifugal Pumps Work

    • 6. Centrifugal Pump Fundamentals

    • 7. Introduction To Centrifugal Pumps

    • 8. Impeller Classification

    • 9. Axial and Radial Loads Explained

    • 10. Centrifugal Pump Impellers Explained

    • 11. Centrifugal Pump Classification by Flow

    • 12. Radial Flow Pumps

    • 13. Axial Flow Pumps

    • 14. Mixed Flow Pumps

    • 15. Multi-Stage Centrifugal Pumps

    • 16. Centrifugal Pump Components

    • 17. Diffuser

    • 18. Wear Rings

    • 19. Stuffing Box

    • 20. Lantern Ring

    • 21. Mechanical Seal

    • 22. Centrifugal Pumps Summary

    • 23. Centrifugal Pump Operation

    • 24. Introduction to Centrifugal Pump Operation

    • 25. Cavitation

    • 26. Net Positive Suction Head

    • 27. Preventing Cavitation

    • 28. Centrifugal Pump Characteristic Curve

    • 29. Centrifugal Pump Protection

    • 30. Gas Binding

    • 31. Priming Centrifugal Pumps

    • 32. Centrifugal Pump Operation Summary

    • 33. Final Thoughts

    • 34. BONUS: How Multistage Centrifugal Pumps Work

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About This Class

Learn all of the centrifugal pump's components, how it works, common problems and how to solve them.

The centrifugal pump is the most common and widely used pump today. Its simple construction, low maintenance and low cost, have made it an ideal pump for widespread commercial application. In this course, you will learn:

  • How a centrifugal pump works.

  • All of the centrifugal pumps main components.

  • Different impeller and centrifugal pump designs.

  • How to read a pump performance curve.

  • How to identify pump faults.

  • And a lot lot more!

The course is designed to take you from zero to hero concerning centrifugal pump knowledge. Even if you already have some background knowledge, this course will serve as an efficient refresher. Whatever your level of understanding, or engineering background (HVAC, oil and gas, marine, power etc.), I can guarantee you will have never taken an engineeringĀ course like this one (unless you have taken one of my other courses!).

Interactive 3D models are used extensively to show you each individual pump component and how these components work together to complete useful work.Ā 

TheĀ course is packed with 2DĀ images, 2D animations, interactive 3D models andĀ 3D animations.

Written content has been read aloud so that you can 'learn on the go' without needing to watch the screen constantly.

Don't waste more time reading this course description, check-out the curriculum, then make an informed decision. I hope to see you on the course!

All the best,


Meet Your Teacher

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SaVRee 3D Where engineers go to learn.


saVRee produces high quality video courses for the engineering market. Our courses are taught by subject matter experts (SMEs) with years of experience in many different industries.

If you are interested in HVAC, Mechanical, Electrical, Automobile, Chemical, Power or Industrial Engineering, we have courses for you!

Courses are presented using interactive 3D models and 3D animations. The 3D models can be exploded into their parts and a cross section feature allows you to see exactly what is happening inside the machine.

We also read written content aloud so that you can learn 'on-the-go'

If you are a professional engineer, or a student preparing for entry into the exciting world of engineering, we guarantee you will find our courses of great benefit.

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1. Centrifugal Pump Landing Page: Hi, John. Here, in this course, I'm gonna teach you about centrifugal pumps. Now, centrifugal pumps have found widespread application in many different industries all over the planet. That the most common type of punk that you're likely to see. But what is it that makes them so special? Why can we use them for so many different processes and so many different applications? Well, in this course, we're gonna look at the center fuel pump. We're gonna look at how it works. Will discuss some of the theory behind how it works. Well, look, all of the main components of the punk on, then we're gonna look how you can properly maintain a centrifugal pump and identify different problems such as capitation. Throughout the course, I'm gonna be using freely animations and interactive three D models to really get inside the centrifugal pump on show you exactly what's happening. By the end of the course, you'll be able to identify a centrifugal pump. Just by looking at it, you'll be able to identify all of the main components. You'll know how it works. You'll know the theory behind it. On the theory, you can also apply to different machinery items in order to better understand how they function. So if you're working in industrial plan already, or maybe you're preparing for a job in the industrial maintenance industry and this is probably useful course of you to take. But don't just take my word for it. Check out some of the free preview lessons. Have a look see if my teaching style agrees with you. See if the content is on your level on it. Make an informed decision. If you want to purchase, of course, thanks very much for your time. 2. Welcome To The Course: Hi, John here. I just wanted to do a short video just to say thank you very much for purchasing this course. This is a welcome video of put in all of my courses, and it's just a way of saying thank you. I know there's a 1,000,001 other things that you could be doing with your time right now on the fact that you've taken time out on actually spent some money to purchases, course and invested time it takes to learn from it is really great and trauma say thanks. The other reason I want to say thank you is because your purchase helps me personally produce more more content on this is something that I really enjoy. I enjoy helping people learn. I enjoy teaching. A new perch in this course helps me continue. So without further ado, let's start the course. Its get stuck right in. I really hope you enjoy it. If you've got any feedback, please do let me know because this is really valuable. It helps me improve the course, the courses in static. I'm going to continue to improve it, change things on feedback is always, always welcome. 20 questions then, please, do you shoot them off to me? I'll answer them as quickly and thoroughly as I can. Great. Thanks very much for your time. 3. Course Overview: So before we go too far into the course, let's just have a quick look at what we're gonna be learning so we can get an overview. So an introduction to pumps these courses actually about centrifugal pumps only. We've got another one coming about. Positive displacement pumps on, essentially, in order for a fluid or gas to flow is going to have to be a pressure difference. This is actually known as Delta P or Pressure Differential. Now, in order to get this Delta P, we need to use a pump so we use a pump to create a Delta P or differential pressure on this thing causes floats. That's the purpose off a pump. Let's have a look now at the lessons. See, we've got here an introduction. Send fuel pumps. We talk about the diffuser. Bernoulli's principle. Then we'll look at impeller declassification. Well, look also at the different types of centrifugal pump designs, such as the radio axle on mixed flow pumps. Then we'll have a brief look at a multistage centrifugal pump. Well, look at all of the centrifugal pumps components. This is going to include things such as wear, rings, stuffing, box, lantern ring, mechanical seals, impeller, shaft and perhaps briefly on the bearings. Then we'll do a short summary on that section on. After that will look at the centrifugal pump on how it operates, so I would look at things such as capitation will discuss how you can prevent capitation. Will also look at protecting the pump on things such as gas binding on, then finally would talk about prime ing the centrifugal pump, so there's quite a lot of stuff to cover in a short space of time. However, we're going to teach lessons in a fair amount D so and hopefully by the end of the course, you should have a very good understanding of exactly how it centrifugal pump works. The different types of Pump Onda also, when you're likely to use different types of pumps for different applications. So let's get stuck in 4. Centrifugal Pump Components Explained: in this video, we're gonna look at the centrifugal pump on. We're gonna look at all of its main components, and I'm going to give you a brief overview of what each of these components are doing later on the course. We're gonna look at each of these components in a lot more detail so you can see we've got a centrifugal pump. This is a cross section side on the opposite side. We have a view that you would normally see when the pump is installed. In other words, when you're walking around the plant, this is how the pump will look. This is its exterior appearance. Normally, a lot of these parts would be painted, so it would look slightly different to this. But let's spin around to a cross section side again so we can see all of the components. And then let's do a quick run through all of the components, and then we'll go back through them and I'll give you a little bit of information about each of the components individually. So on the end off the pump, we've got what's referred to as a veloute casing that is this item all the way around you on the veloute casing is shaped a little bit like a snail. It's a very important part. The centrifugal pump on it houses the impeller within the veloute casing is an impeller. That's this item here. The impeller has wear rings. Two located roughly here. Andi, we've also got on the opposite side A ceiling arrangement that is this section around here , Andi, After the ceiling arrangement, we've got some bearings. In this case, these are anti friction bearings or more comical ball bearings on we've got two of those. The pump itself is set up in a cantilever arrangement. What they referred to is an overhung pump. But let's just pulls the animation for a moment and then we'll go back through those components. Andi, I can give you a bit more information about each component. So the veloute casing, as you can see, a very distinct shape, a lot like a snail. The veloute casing turns to kinetic energy that's been imparted on the liquid from the impeller into pressure energy. So we're exchanging velocity for pressure. There are two different types off veloute casing on these are single flutes and double veloute sauce. The double veloute design has the advantage that the radial loads imparted on the impeller on bearings are far less compared to when using a single veloute. It's also possible to use a diffuser on the diffuses job is much the same as that of a veloute. We're gonna convert some of that kinetic energy or the velocity of the fluid into pressure energy. The actual science behind this is known as Bernoulli's principle. Let's move on to our wear rings, where rings are used to stop leakage from the discharge side back to the suction side because there's a pressure difference is always gonna be a tendency for the discharge fluid , which is a higher pressure. You want to go back to the suction side off the impeller, which is a lower pressure wear. Rings are used to reduce the amount of leakage passing from the discharge side to the suction side of the pump. After the wear rings, we come to the impeller. The impeller consists of a series of veins and can have are the one, two or no shrouds. We can see the front trout in this section here. We can see the rear shroud in this section here, there are three different types off impeller used for centrifugal pumps. These are the open, semi open and closed type in pillars. Liquid is drawn in through the center of the impeller through an area known as the impeller Roy. The liquid is enthrone outwards away from the center. I of the impeller, due to centrifugal force, notice that the impeller vanes are angled away from the direction of rotation. On that, the distance between the veins gradually increases as the liquid passes towards the discharge side of the impeller. This changing area converts the velocity or kinetic energy imparted on the liquid to pressure. As with most pumps and valves, there's gonna be a central shaft or a spindle that penetrates through the casing and connects onto an actuator or drive. In our case, we're using a pump on the main shaft, comes out from the back of the impeller, passes through several bearings and then would connect onto the prime mover, which is normally a type of electric motor for industrial applications. It's almost always going to be a free phase electric motor. We can see the ceiling arrangement in front of us now. We've got five layers of compression packing on in the middle with got a lantern ring. Compression packing is more or less like rope that's been soaked in some form of wax or soap. We wrap the packing around the shaft on. Then we compress the packing together in order to get a tight seal, the area where the packing and the land to bring sits. He's known a stuffing box, the concept behind packing his thousands of years old. But it's still employed today as packing his relatively cheap, although, as we'll see later in the course, does have some severe disadvantages compared to a different kind of ceiling arrangement known as a mechanical seal. Because the backing is more or less rope or is usually made of a fibrous material, it will gradually heat up as the shaft is rotating. In order to prevent damage to the packing, we're going to need to cool the packing on. This is done through the lantern ring. The land to bring itself has holes on. We're going to allow liquid to pass through the holes in the land to ring, then through the fibrous material of the packing itself. On this liquid is then going to cool the packing. The liquid used is usually the process liquid being pumped and can be taken directly from the process itself. However, it's not possible to take the process liquid for cooling of the packing if the process liquid itself could be considered either corrosive or ihr oh sieve. If this is the case, then an external source for the cooling liquid must be found. As we come along the shaft, we can see we also have a gland follower. This item is used to tighten the packing in order that we can get an effective seal. There's always going to be liquid dripping out from the underside of the packing in this area. Here, pump manufacturers will typically detail how Maney drops should be dripping out for a minute. Over time, the packing will become worn and it's necessary to tighten up the gland follower in order to compress the packing still further. It's easy to identify when the packing has been completely worn out, because tightening of the gland follower will no longer reduce the leakage rate through the packing, we go further along, we can see two bearings for supporting the weight of the shaft on the impeller. The two bearings were using for this pump are called anti friction. Bearings, more commonly known as ball bearings, can see that we've got two of them. These types of bearings are good around bearings. They can handle very iradio loads on, and some axle loads resume in. We conceive the bearings in operation can see the bearings rotating. Now the balls themselves are retained within a spacer, and the bulls in the space of rotate within an inner and outer race. We've also got the main drive shaft. In our example, the chef connects to an electric motor and allows us to mount all items necessary to operate the punk along one main axis of rotation. We're gonna mount the bearings, the packing, the lantern ring, the impeller on the chef key all onto the main drive shaft. The shaft itself is usually going to be manufactured from stainless steel. As this material has very good erosion and corrosion resistance properties as well as being very strong. We'll spend the bump around so we can see again from the outside will from its external appearance, notice that you'll only see the shaft coming in on the left side. Then you see the bearing housing. And if we zoom in, we can see that we've got access to the gland follower. This allows us to tighten the follower up in order that we can reduce the leaking or regulate the amount of leakage through the packing, resume out within, got the attachment to the veloute casing, and we come back around, we can see the eye of the impeller. So we're looking here at the suction side of the pump on If we got to the top here, we are now looking at the discharge side off the pump. 5. How Centrifugal Pumps Work: in this video. We're going to look at the centrifugal come, and I'm going to explain to you how it works. So it's diving. Still a little spin here is the exterior view of the pump Again, if we spin around the other side, we've got a cross section now. I'm not going to go through the terminology in the components because we covered that in another video. But let's just go through the components that we actually need to talk about. And the components are the impeller on the veloute casing. So how is it that the centrifugal pump works you can see from the design and the animation that the pumps construction is quite simple. Essentially, we've got an impeller rotating within a veloute casing, and as it rotates with a liquid, we're creating pressure on this pressure differential. That is, the difference between the substance side of the punk on the discharge side of the palm is what causes the liquid to flow well in order to understand, out of Centerview upon works, we need to have a very quick look at some of the theory. So let's first pull up a open centrifugal pump impeller so here we are. We're now looking at a centrifugal, semi open type impeller. So the type of so really was in close type and this one is a semi open type with semi closed depend on how you look at it, as you can see is rotating in a clockwise direction. We'll give it a little spin we can see. Also, there's a shaft in the middle of the impeller on a shaft key which connects the shaft to the impeller itself. The suction side of the impeller is this middle area here. That's what we call the eye of the impeller. And as we draw the liquid in, we're going to create a negative pressure at the eye of the impeller. And then we're going to throw the liquid outwards radio early, away from the center of the impeller towards the outer periphery off the impeller. The reason the liquid is frying out was radiantly away from the center of the impeller is because of the friction between the impeller on the liquid. As the impeller moves, some of this movement is imparted onto the liquid on because the impeller is rotating from a center axis, the liquid has a tendency to be thrown outwards away from the eye of the impeller. Now the force that causes this is Mona Centrifugal force on. Because this type of pump uses centrifugal force, it's called a centrifugal pump. If you've ever driven around a corner very fast in your car, you'll know that if you're driving around a corner and turning into the left, you have a tendency to be thrown outwards to the right. And this is centrifugal force. Now the impeller does the same job, although on a much smaller scale. It rotates very fast from a center axis of rotation on the liquid that is drawn into the center is thrown outwards to decide radiantly away from the eye of the impeller. This centrifugal force gives us a large increase in velocity, which weaken later, turn into pressure. So let's just pulls the animation, and I can show you the flow path off the liquid. But the animation is now paused. Zoom in liquid would come. In fact, let's just do as a liquid would flow. We would flow into the middle, like so the liquid is then thrown outwards. Radio early on, it's gonna go between these two veins or between a set of veins, I should say between a pair of veins and then it's gonna flow up along here. It's gonna be thrown outwards, and then it's gonna leave the impeller. So let's do this time. But this time we just had some arrows to mark the flow. So, as you can see now, the liquid would flow out. Radio Lee. And as it does so as it flows out through the channels, the Flow Path area is going to gradually increase. And as it increases, we're gonna get a reduction in velocity on an increase in pressure. So that is essentially what the centrifugal impeller is doing, its converting velocity into pressure. And that's what we need in order that we can get flow. But let's now have a look at the theory behind this on the theory behind it is known as Bernoulli's principle. Okay, so here we are. This is our newly principal simulator. You can see we've got an underground pipe. We can assume this is gonna be an underground water pipes. I'm gonna turn the dots off, but you can see that the flow is from left to right and If we take a speed gauge, we can put a speed gauge on the point. Another speed gauge here and we can see factor raises up to services slightly. We can see that these two points the flow is constant on the speed remains the same, irrespective of where we put our speak. Ages conduce like this. And this makes sense because we've got a constant flow. Now this constant flow is required in order to apply Bernoulli's principle. Bernoulli's principle states that if we have a constant flow and we change the flow path area, then we get a corresponding change in pressure. Andi velocity. So let's put the theory to the test. I'll take my pressure gauge and I'm gonna install it, but we can install it roughly here, so it's slightly in front of the speed gauge in relationship to the flow, and I'll take my pressure gauge and I'll try and do roughly the same thing again. So it's a bit further down here, and there we go. We've got the exact same pressure on the exact same speed. So Bernoulli's principle states that if the flow is constant and we're just the flow Pap area then we'll get a change in speed on pressure. So I'll extend the pipe and I'll make the point a little bit bigger in diameter and we can see already. Speed has dropped its now 0.7 meters per second instead of 1.6 on. The pressure is increased. Could do also here again. The speed has dropped 0.4 meters per second on the pressure has increased again. So we know that if we increase the flow path area, we get a reduction in speed on an increase in pressure. And that's what Bernoulli's principle states. If we go the opposite way, we can try and make the float by fear slightly smaller. In fact, I have to extend it a little bit because otherwise you don't get a pressure reading and we can see the speed on the left is 0.4 meters per second. But the speed on the right has increased. Just take this handle, reduce it and now we can really see that if we create a massive restriction in the pipeline , then we get a huge reduction in pressure on a massive increase in speed. Conceal your speed is waas about 5.65 point seven meters per second. So quick recap if the flow path becomes larger, the speed reduces and the pressure increases. If the flow path becomes smaller with speed increases and the pressure reduces and you can see we've got quite a lot of pressure reduction when we compare both the left and the rights. So let's not go back to our impeller on. Apply the new lease principle in order to figure out how it works. So here is our impeller again and we can see that the flow path area increases as the flow flows out. Radio Lee away from the center of the impeller on We know now that this increase in flow path is going to cause a reduction in velocity on an increase in pressure and that is essentially how a centrifugal pump works. Now after the impeller, usually there'll be a veloute casing or a diffuser. But the concept behind the design of the veloute casing and diffuser is the same as for the impeller. We know that we need to increase the flow path area in order to increase the pressure. And as you can see on the diagram now, the value casing does just that. As the liquid is discharged from the impeller, it's gonna flow around the veloute casing and we're going to get a reduction in velocity on an increase in pressure. And that is essentially how a centrifugal pump works. There really is nothing more to it. So let's go back to our main centrifugal pump model on. We'll do a very quick recap. So here we are. We're looking at centrifugal pump. Let's imagine we are the flow, the centrifugal pump Impeller is spinning. We're gonna be drawn into the impel awry because it's creating a negative pressure. So we've bean drawn into the impel awry. We're now going to flow out off the veins. You can see the veins just on the inside off the impeller. We'll see if I can actually get through the veins. Could be quite tricky. Excel things pretty tight that was flowing through here through here, Friend. Further, further further being thrown out radial e on. Then we're gonna exit the impeller and go to the veloute casing. Now we're inside the veloute casing and look as we are thrown out of the impeller, we enter the flu casing and notice how much more space theories as we move towards the discharge pipe. That's this pipe that we can view at the top of the screen compared to how much space there is on the opposite side. And C is getting continually narrower if we wanted to flow back the other way. So down this side here is quite narrow. The diameter of locating is gradually increasing until we get onto this side here, and that means that flow path is gradually getting bigger and all of a sudden we got lows of space, and that means the velocity has decreased on. The pressure has increased on. Then we can move on our way through the rest off the system. So that's it. That is how the centrifugal pump works. 6. Centrifugal Pump Fundamentals: in this video, we're going to look at centrifugal pump designs and classifications. We're going to look at how you can classify the centrifugal pump based upon the impeller used the flow type, the support given to the impeller, the suction type on stage type. By the end of the video, you'll know what radio axle and mixed flow pump types are. You'll be able to identify and overhung on between bearings. Pump, as well as being able to identify a closed semi open on open type in Palo in the final part of the video. Well, look at the difference between a single stage, a multistage centrifugal pump. Centrifugal pumps could be classified by the type of impel oh they use, or the flow tie in palace could be on the fully enclosed, semi closed or open in closed typing. Pillows are ideally suited for pumping foods with a small amount off suspended bodies. This would include freshwater or seawater. Open typing pillars are used to pump fluids with a large amount of suspended bodies. Typical applications for open typing pillars would include sewage treatment systems. In addition to classifying the pump by appellate type, we can also classify the palm based upon the flow. Centrifugal pumps are categorized based upon three flow types. These are Radio axel on missed radio flow. Centrifugal pumps are the most common of the three used in industrial applications. Radio flow pumps discharge fluids perpendicular to the main pump shaft. That is to say, they discharged the fluid at a 90 degree angle compared to the orientation of the pump shaft. Radio flow pumps are ideal for many pressure and flow applications. Mixed flow pumps discharge Florida and angle exceeding 90 degrees relative to the pump shaft orientation axel flow pumps used for low pressure, high flow applications. Almost no radio forces imparted onto the flowing fluid, but the pump is still classified a central fuel because some small part of the fluids movement is radio. It's also possible to classify centrifugal pumps as being on the single stage or multistage . The example we're looking at now is a single stage centrifugal pump. The pump consists of only a single impel. Oh, the example we're looking at now is a multistage centrifugal pump. The pump consists of five in pillars and is thus classified is a five stage centrifugal pump. We're going to be discussing this type of pump later. In course, centrifugal pumps could be classified as overhung or between bearings and overhung. Palm has an impeller that is only supported by a chef. On one side between bearings, Pump has an impeller that is supported on both sides by a common shaft. We can see an example of an overhang pump on the left side of this diagram, and we can see an example of between bearings type pump on the right side of this diagram. We can also see on the diagram that the impeller on the left is a single suction type impeller, whereas the impeller on the right is a double suction typing pillow. Single section typing pillars have a suction inlet on only one side. Double suction typing pillars have suction in Let's on both sides of the impeller. So if we put together all that we've learned from this lesson, we can see that the pump that we're looking at now is an overhung radio flow, single stage, single suction, fully enclosed centrifugal pump 7. Introduction To Centrifugal Pumps: introduction to Centerview will pumps centrifugal pumps, the most common type of pumps found in many facilities. Centrifugal pumps enjoy widespread application, partly due to their ability to operate over a wide range of flow rates. On pump, it's you can see I've got a centrifugal pump. We've got the suction side, which is in the middle, and then we've got the precious side. The top here, which is also known as a discharge side, can see the impeller within the casing of the pump on the drive shaft fledge, which is attached to descend over here. So that is essentially a centrifugal pump or one of the designs that you're likely to see. Centrifugal pumps consist of a stationary pump casing on impeller mounted on rotating chef . The pump casing provides a pressure boundary for the pump and contains channels to probably director suction and discharge float. The bomb casing has suction and discharge penetrations for the main flow path of the pump, on normally a small drain and then fittings to remove gases trapped in the pump casing or to drain the pump casing for maintenance. What I'm gonna dio, I'm gonna read through each of these lessons that should have backed him into Not the star will go through. They're not particularly long on. Once we've gone through the entire lesson are gonna go back. And I'm gonna comment on me to the paragraphs on add some more notes and perhaps somewhere in experience so that you get more from the lesson. And if we just sit here reading through the lesson and try to make an audiobook out, of course. The below image shows a simplified diagram of a typical centrifugal pump that shows the relative locations of the pump. Suction impeller veloute on discharge. The pump casing guides a liquid from the suction connection to the center or eye off the impeller. The vein to the rotating impeller in part radio and rotary motion to the liquid, forcing it to the outer periphery of the pump casing. Where is collected in the outer part, the punk casing called the veloute. So here we can see absolute placing shaped a little bit like a snail. You're gonna hear me say that quite often for out this course, The impeller is item A. That's this section here on the veloute casing. You see, outer piece. We're gonna discuss this in more detail. Well, let's just carry on and finish the lesson. The veloute is a region expands in cross sectional area as it wraps around the pump casing . The purpose of the flu is to collect a liquid discharge from the periphery of the impeller at high velocity and gradually cause a reduction in fluid velocity by increasing the flow area. This converts the velocity had to static pressure. The fluid is and discharge from the pump through the discharge connection, so suction always in the middle of the centrifugal bump on discharge on the outside. So such as here, centrifugal pumps can also be constructed in a manner that results in two distinct the lute's eat, receiving the liquid that is discharged from 180 degree region of the impeller. At any given time, pumps of this type pickle double veloute pumps and there may also be referred to his split flu pumps. In some applications, the double veloute minimizes radio forces imparted to the shaft and bearings due to imbalances in the pressure on the impeller. A comparison of single and double veloute centrifugal pumps is shown on the image below, so you can see here a single veloute casing that's image on the left hand side on a double veloute casing that is image on the right hand side. Let's just go up to the top and we'll work our way down again. So here first we're looking at centrifugal pumps. The type of centrifugal pump we're looking at here is a single stage pump. The resigned one impel. Oh, it's also what they refer to is an overhung pump because it's only supported on one side What I mean years. The impeller is only supported by one singular shaft, so it has a canti lever arrangement. That's what they referred to is an overhung pump. So there's different types of century were bumps, although this one is very common as a single veloute casing and a single impeller and it's supported are only one end. Irrespective of the pump, design is always gonna be a rotating shaft. That attach is to the impeller or the imp Ellis, and this is what gives rotary motion to the impeller or in palace bun. Casing itself is a pressure boundary. It's essentially just a way for us to contain the process fluid that's being pumped although it serves another function as well. Let's go down and look at this diagram. We can see it's got a very unique shape. Look at the distance here between the impeller and the casing on. Then look at the distance here between the impeller in the casing, you'll notice that it gradually increases. If you also look here on the impeller, you can see the distance here between the two veins is far less than the distance here between the two veins. So why are we always increasing the flow path or the flow area? You can see we've increased the flow area and we've increased the flow area here between the veins or in the channels specifically. Well, the reason is, if we increase the area, then we get a velocity reduction on a pressure increase. This is known as Bernoulli's principle, which we're gonna look at later in the course. But essentially, if you increase the flow area, you'll get a velocity reduction on a pressure increase. Inversely. If you decrease the Flow Path area, you will get an increase in velocity on a decrease in pressure. So keep that in mind pressure and velocity, an area they will have a relationship in fluid dynamics on. If you know these relationships, you'll often be able to understand our machinery works just by looking at it and understanding the principles or the theory behind its design. Let's go down a bit further. We can see here a centrifugal pump. Its exterior appearance We'll do is a lotus model up in the moment and we'll talk through roughly how it works. Although we're also gonna look at that later in the course as well, along with all of the components. So we got a single veloute on with discharging their directly from the impeller to the casing. A double veloute is discharging from the impeller to the casing, but the casing has been split into two separate sections. Now the reason we do this is because it allows us to balance the radio forces that are imparted to the impeller and bearings radio forces of those forces air imparted at 90 degrees to the shaft itself. In other words, radio forces of those perpendicular to the chef Axel forces of those parallel to the shaft . So that's the different types of forces that we're gonna get. We're gonna get radio or we're gonna get actual. So let's go up. Will load Pump. This one's slightly different from the other model we use. This one's a little bit older. In the next couple of lessons, you're gonna actually see how the pump works on. We're gonna get run down all the components. So you go. You can see a center fuel pump attacked, exploding into various parts. I'm gonna assemble the pump, and that's how it is normally going to look when you're walking around the plan. I want to get into details here, but will point out the interesting bits that you will see when you're walking around your plan or whenever you're staring at one of these pumps on a day to day basis. So this is our exterior appearance. Could see we got the chef coming in on the left hand side. This is gonna be connected to a prime mover. This might be a diesel engine on electric motor Pepsi steam turbine. It depends if using a turbine, you're likely to use some sort of gearbox. We then got out bearing housings, and then the casing connects on to the end here onto the veloute casing itself and you could see the blue casings got a very unique shape. It's also got these fins sticking out beside these could potentially be acting as he exchanges. I don't know the exact intricacies with this pump, but I'm guessing that could perhaps be what they used for, or perhaps for maintaining some form of balance. If we zoom in, we can see that we've also got a inlet. This is the suction side off the pump. So we're gonna be drawing the liquid in here on into the center, off the impeller, an area that's known as the eye of the impeller. This is gonna be where negative pressure is created. So in this spacey, we're going to create a negative pressure. When we spend the food around, we're gonna increase the pressure on. We're gonna discharge it or destroys the fluid through this discharge report here on, the pressure is going to be higher than at the suction poor. So suction in the center for the impel awry discharge from the side of the impeller. And then out of this point here, let's just have a very quick look at the impeller self satirical called large impeller here , that is. You saw it from here. I will look at the construction of the impeller of it later on. But I should concede. Sits directly in the casing. Assemble the model again. We can see the veloute casing this very unique snail like shape. And that is essential as far as we didn't go in this lesson. Because I want to do it in a logical manner of work through the pump on its components. In the theory as we go through the course. Ideally, we wanted to do here is just show you the exterior appearance so that you'll be able to identify Centrifugal come just by looking at it as mentioned previously. They're different designs, but this one is an overhung pump notice here, the chef comes in from only one side on the weight of the impeller is then held by two bearings which are installed about here on Dhere. So overhung pump. If we had a chef that came in from both directions, then we would call this a between bearings. Pump right. Let's move on with the next lesson 8. Impeller Classification: in pellet gasification in Bella's of pumps, a classified based on the number of points that the liquid can enter the impeller and also in the amount of webbing between the impeller blades in palace could be other single suction or double suction. The single suction impeller allows liquid to enter the center of the blades from only one direction. A double suction impeller allows link between to the center of the impeller blades from both sides. Simultaneously, the below image shows simplified diagrams of single and double suction in palace. So let's have a look Now we've got single suction. The liquid is being drawn in on the left side for the impel awry is going to be thrown out radio early on, it's gonna exit through these veins on the other side. We've got a suction on the right on a section on the left. So was sucking the liquid in from both sides. Notice. However, we've also got one common shaft here, going directly through the entire impeller on. We've got one shaft here, also going through the entire impeller. So where is before? If we had a chef coming in here and then it was holding up the weight of the impeller but there was no shaft coming out on the left hand side. Then this would be an overhung pump were supporting the impeller on only one side. That's typically how you're going to see a single sumption impeller you're not likely to see with a shaft going through by offsides. However, if we have a suction on both sides of the impeller, then we might very well have a Shafik comes directly through the impeller from both sides. Now this is a between bearings pump because without bearings on this side, I would have bearings on this side if we had a overhung bump, then we would need only bearings on this side because we would have a shaft that goes to the impeller and connects from only one side. So overhung pump the shop comes in on only one side of the impeller and then for a between bearings pump the shaft is going to go through both sides off the impeller. However like a say single suction I, then you're likely to have an overhang pump double such and I Then you are likely to have a between bearings. Pumps can actually see the difference here on this image or go to the center. Got the casing year around the side on the flow of the impeller is coming in Withdrawing the liquid in has been thrown out Radio Lee pressure is increasing and then we will discharge the liquid. The impel on this side were drawing the liquid in from both sides on the left. On the right, we throw the liquid out Radio Lee increased the pressure on in the flow carries on along its journey within the system So I take it from type single assumption on double suction in palace could be open semi open were enclosed the opening bell A consists only of blaze attached to a hub. The semi open impeller is constructed with a circular plate attached to one side of the blades. The enclosed impeller, a circular place attached to both sides of the blades enclosed impel, is often referred to as shrouded in palace. The blow image illustrates examples of open semi open on enclosed in palace. So here we can see an open impeller notice that we just got the veins on this model. So the vein to during the work go to the semi opening Pella Now the semi open Impeller has the veins as well. But this time we're gonna have a back place or what they refer to as a shroud and we will mount the veins onto the shroud being closed. Impeller What? I also call a closed impeller, his one as to shrouds one here on one on the other side We're gonna have the veins sandwiched between the two shrouds can also see We've got an enclosed in Pella here. I semi impeller here and they open impeller here Now the open impeller is actually quite structurally weak. The semi in Bellary is like stronger and then closed Impeller is mechanically mawr strong or is stronger than the opening Pell. Oh, this is simply because the open impeller does not have much of a support structure. There are also other differences such as when and for what purpose You will use each of these types of imp Ellis So what I've done, I've created a separate video It's gonna be the next lesson where we discuss only in Pelous The appellate sometimes contains balancing holes that connect the space around the hub to the suction of the impeller. The balance in holes have a total cross sectional area that is considerably greater in the cross sectional area of the annual space between the wearing ring On the whole, the result is such an pressure on both sides of the Impeller hub which maintains hydraulic balance of Axel Frost. I'm gonna load up a model on. I'm gonna explain Teoh exactly what we talked about. When we talk about Axel thrust on why we get Axl Thrust due to the pressure differential created by the Impeller. So in the next lesson will look at the impeller in greater detail. We're gonna look at all three of these designs open semi Andi enclosed. But for now, let's just kind of a quick look at Axel on radio loads. 9. Axial and Radial Loads Explained: So let's just have a quick chat about Axl and radio loads. So if you've got an axle load, an actual load is going to be a load that is applied in parallel to the direction of the chef. So we're going to be applying the load either to the right or to the left. That is an actual load. A radial load is a load that is applied perpendicular to the direction of the shaft or the alignment of the shaft. We're gonna apply the load, and it's gonna be going, for example, off here or two left or down or to the right. That is a radial load. Now we create excellent radial loads at the impeller. A typical axle load will be creative because of the pressure to friendship on the backside of the impeller. Compared to the front, a radial load will be created because we're throwing the liquid outwards rarely. So it's coming away from the center of our impeller section here, Andi, it's gonna be thrown out regularly to absolute casing. So that is our radial load on our axle load is created used to the pressure differential across the impeller. If the pressure difference is quite high, which happens sometimes it's start up, then we're gonna have to have special bearings in order to deal with this. And these bearings and owners thrust bearings designed specifically to be able to handle axle loads. Ball bearings like the ones we're looking at now. These types of bearings are used to handle high radio loads. Andi have rich or medium axle loads, so they're a good all round bearing. But they're not gonna be able to handle very high axle loads. And that's why we sometimes have frost bearings installed instead of ball bearings. So that is Axl and radio loading as promised. Let's not get on and have a look at the different types off pump Impeller. 10. Centrifugal Pump Impellers Explained: in this video, we're going to look at centrifugal Pump in Pelous. We're going to look all of the main components that make up an impeller. We're gonna look at how the impeller works and then we're going to look at different types of impeller designs on the pros and cons associated with those types of in palace. So here is ah, centrifugal pump. I'll do a little spin. You can see the exterior appearance here and if we spend back the other way, we can see a cross section of the pump as well. Impeller is housed within the veloute casing on the imbalance of rotating item that we're looking at now. Before we have a look at how the impeller works, let's go and have a look at the parts that make up on impel. Oh, as you can see, we've got quite a spiral e shape. This is the impeller view from the top. We've got a bore in the middle that allows us to connect the shaft to the impeller on the angular rotary motion from the shaft can then be transferred to the impeller. The items indicated now called veins and the gaps between the veins on owners channels. On the back side of the impeller is a base plate. On this plate is what they refer to as a shroud. It's possible for Intel is to have 21 or no shrouds. It's just rotate back around the other side. The type of impeller we're looking at now is called a semi open impeller because he only has one shroud. There are two other designs of impeller and these referred to as closed well open. We're gonna look at these different designs later in the video. Now that we know the names of all the impels main components, let's have a look at how exactly the impeller works. Well, the impel its job is to change kinetic energy into pressure energy. So we're exchanging velocity for pressure. We use a prime mover such as an electric motor. In order to rotate the impeller, the impeller rotates within a fluid and as it does so, it creates a negative pressure around the impeller oil, which is located at the center of the impeller. This negative pressure draws fluid into the impeller. Because the impeller is rotating, the fluid is thrown outwards. Radio early due to the centrifugal force that's imparted on it from the impeller notice that each of the veins has a gradually increasing gap between it and its neighbor. For example, we can see here that the gap is quite small and when we get to the outer periphery, the gap has become quite large. This change in dimension is the reason the in pelican change velocity to pressure. Her new lease principle states that if we have a constant flow on a change in area, then the velocity will be correspondingly changed as well. So if we have a steady flow and we have an increase in area, will get a corresponding reduction in velocity. If we have a steady flow on, a decrease in area will get a corresponding increase in velocity notice. Also, that the impeller has a certain number of channels on the number of channels varies depending upon the fluid being pumped for fluids with few or no suspended bodies such as freshwater, the impeller will have between 5 to 10 separate channels. As the number of suspended bodies within the fluid increases, the number of channels will decrease, varying the number of channels depending upon the flowing medium will ensure the best possible pump performance. Once the fluid leaves, Impeller is going to be discharged to every veloute casing or a diffuser, both of which help convert more of that kinetic energy into pressure. Let's now have a look at the different impeller designs. As already mentioned, it's possible to have an open impeller that's one has no shrouds, such as the one we're looking at now. A semi open impeller, which has one trout and a fully closed impeller, which has a shroud both on the top and the bottom opening fellers are ideally suited for handling fluids with a large amount suspended solids. However, they are also structurally weak and inefficient. Semi open or semi closed, Impeller is have a greater mechanical strength than opening pillars due to the shroud where the veins amounted. This type of impeller is ideally suited to handle fluids with small amounts of suspended solids, closed type in pillars of the most efficient type of impeller. Compared to descend the open and fully open designs closed type in Bella's employees, a front and a back shroud on this use of shrouds gives a closed impeller and much greater mechanical strength compared to the open and send the open impeller designs. Although closed impeller is can punk stories or fluids with a large amount of suspended solids. The wear A on the impeller will be excessively high. Closed type impeller is typically used for fluids with a very low number of suspended solids in pellets were also classified by suction type. This could be a have a single or double a single England impeller allows the fluid to enter on only one side off the impeller. The single in the impeller is the most common type of impeller used for centrifugal pumps. The double inlet impeller allows fluid to enter from both sides off the impeller. It's also possible to classify and pellets by the flow type radial in pillars are those in palace that we've been looking at for at this video. These are in pillars that you centrifugal force to throw the fluid out radiantly away from the center. I off the impeller mixed blowing pillars use a combination of radio and actual flow. Axel flowing pillars rely almost exclusively upon axial flow, although some off the fluid is thrown out radiantly due to the centrifugal motion of the impeller. That is why Axel Flowing Pillars is still classified. A centrifugal impeller 11. Centrifugal Pump Classification by Flow: centrifugal pump classifications by flow send fuel pumps could be classified based on the manner in which fluid flows through the pump. The manner in which fluid flows through the pump is determined by the design of the punk casing and the impeller, the three types of flow through a centrifugal pump. Our radio axel on next. 12. Radial Flow Pumps: radio flow pumps. These are the types of pumps that we've been looking out already to standard centrifugal pump can see one here very similar in design to the ones that we looked at previously in a radial flow pump. Liquid enters at the center of the impeller and is directed out along the impeller blades in a direction right angles to the pump shaft, the impeller of a typical radial flow pump and the flow through a radial flow pump is shown below. So this is our radial flow pump, conceded blue casing in Bella, the flow coming in through the center being thrown out. Radio Lee into the blue on. Then it goes out the top, so that's a radial flow pump we don't need to discuss out. I think in much more detail because we really talked about that quite a lot in the course. Let's have a look at the other two types off pump design 13. Axial Flow Pumps: actual flow pumps in an actual flow. Punk in Pella pushes the liquid in a direction parallel to the pump shaft. Actual flow pumps is sometimes called propeller pumps because they operate essentially the same as the propeller of a boat. Impeller of a typical axes flow pump and flow for an actual flow pump is shown below. So you were looking at an actual flow impeller, and you can see how it's installed here. It's quite tight clearances between the impeller on the pipe into which has been installed or the casing on. The interesting thing about these pumps is that there is very, very little centrifugal force actually passed on to the liquid itself. Actual flow pumps are good for handling large volumes off liquid or fluid, but they're not very good for increasing the pressure off the fluid. So, in other words, we're gonna be able to pump a lot, but we're not going to be able to have a very high pressure. It's interesting that they're classified a centrifugal pumps because they simply don't transfer much energy or they do not impart much centrifugal force onto the liquid itself. And you can see this because the pipe or the construction that this in palace sitting is straight. Now, this is just going to continue upwards. Now, if we had a lot of radio motion or radial force imparted on the liquid and we'd essentially be just throwing it against the side off this pipe or this casing so we obviously don't have so much radio force invited onto the liquid, the force is more just drawing the liquid further through the pipe for the casing. So keep that in mind when you look in a different pumps. If you see that where the impeller sits, there's gonna be a big casing almost perpendicular to the direction of shaft. Then you know that the impeller they're using is gonna be one that uses radio flow. However, if you've got impeller such as this one here where there's very little space given to throw the liquid out Radio Lee, then this is no gonna be a radio flow pump. It's most likely to be axel flow. Let's not go have a look at a mixed flow type pump 14. Mixed Flow Pumps: mix flow pumps. Mixed flow pumps borrow characteristics from both radio flow and axel flow pumps as liquid flows through the impeller of a mixed flow pump. The impeller blades pushed the liquid out away from the pump shaft onto the pump. Suction on angle greater than 90 degrees, the color of a typical mixed flow bump on the flow for, um, explode pump is shown below, so we've got a mixed fly. Pampuro explore Impeller, since they were drawing the liquid here into the pump, is passing across the impeller on it is being thrown out again racially, but also actually into the discharge or into the veloute casing. Mixed flow pumps are just a compromise between a standard radio flow of centrifugal pump on an axle flow pump. As a previously mentioned axel flow pumps of very good when you need a high flow rape, but perhaps not a very high head of pressure. Radio flow bumps very good. Achieving a high pressure, providing that you put them in Siris one after another on the mixed flow bump is anywhere in between. I should also mention, though, that there's gonna be other characteristics that dictate when you're going to use each of these types of pumps. And some of the biggest characteristics are gonna be things such as what pressures you need to achieve what sort flow rates you need to achieve on what sort of temperatures is the pump gonna be operating at on. What's the effect this is gonna have on the pump on its ability to create a pressure head or to maintain afloat? 15. Multi-Stage Centrifugal Pumps: multistage centrifugal pumps a centrifugal pump with a single impeller that can develop the differential pressure of more than 150 p. S. I between the suction and discharge is difficult and costly to design and construct. A more economical approach to developing high pressures with a single centrifugal pump is to include multiple impel is on a common shaft within the same pump, casing internal channels in the pump casing route, that discharge of one impeller to the suction of another impeller. The low shows a diagram of the arrangement of the in pillars of a five stage pump. The water enters the pump from the top left passes through each of the five pillars in Siris go from left to right. The water goes from the veloute surrounding discharge of one impeller to the suction of the next impeller. A pump stage is defined as that portion of the centrifugal pump, consisting of one impeller on disassociated components. Most centrifugal pumps are single stage pumps containing only one impeller. A punk containing seven pillars within a single casing would be referred to as a seven stage pump or generally as a multi stage from so let's have a look at a multistage pump. We load up the freedom model and then we can have a proper look. Okay, so here we are. We're looking at a multistage centrifugal pump, as promised. I told you would see a diffuser on. You can see one here. This is a diffuser. You follow my house. So diffuse a ring or diffuser casing on its mounted around the impeller. The diffuser itself is stationary, mounted into the casing of the pump. But notice the veins of the impeller on the right. Here, when the mouse is are sloped away, just get a better view. This lighting here, upwards on the veins on the diffuser are sloping downwards. The case as we talked about earlier direction, off rotation or not, the direction of rotation but the direction with relationship to each other between the appellant diffuser, they are opposites again stuff. Quickbooks, if we can get a better view, this vein comes downwards. Andi, you just go here. Here we go. So here it comes from here, sloping that way on the other side, on the diffuser ring from here. Sloping that way. So we know that we got diffuser on we've got an impeller. We're using diffuses here on a multistage pumps to save space. If we had a multistage pump that relied on a series of veloute casings in this part would be very large. We've got five in pillars and these five impels require five pollutes. So no, only do we need a larger pump because the flu itself is much larger than diffuser. But we also have to worry about the radio loads imparted onto the bearings. The radio lows from a diffuser are quite balanced because we're throwing the liquid out on its then existing the diffuser for here through here and then through here three year. And it's quite balanced if we have a veloute casing and the pressure is going to gradually increase around the veloute casing or as the fluid flows around the flu casing, this gives us on uneven radio load, whereas here on diffuser, we have quite an even radio load because the diffuser ring is the same all the way around. So if we using diffuser rings, we save on space Onda, we can also reduce the radio loads imparted onto the bearings. So that's the reasons why we would use diffuser rings, especially for multistage pumps. So let's follow the flow. I got the flow coming in here on. Then it's gonna be drawn in to the I off the impeller. It's coming in here. It's gonna be discharged. Rady out was through the diffuser and then it's gonna come back around around here into the next impel awry. We're going to repeat the process, can see again on again, uh, again into the final. I thrown out Radio League on, then into he discharged line. Which is this one here. No ideas. We've got a diffuser ring on all of these in pillars. You don't have won the last stage. I'm not sure the reason for this, but let's just go up when we can have a look at the flow path again. This one's a bit easier to follow. Coming in the left into the impeller disguised out into another and Bella into third stage four stage fifth stage on doubt. I'm always done. There is increased. The pressure increased, the pressure increased the pressure, increased the pressure on then how it goes to the discharge flying. This one is actually multistage centrifugal pump used for a boiler feed water system. So that's where we got the design from, and that is essentially how a multistage centrifugal pump works. 16. Centrifugal Pump Components: centrifugal pump components. Centrifugal pumps vary in design and construction from simple pumps with relatively few parts to extremely complicated pumps with hundreds of individual parts. Some of the most common components found in centrifugal pumps are wearing rings, stuff in boxes, packing and lantern rings. These components are discussed in more detail in the following lessons. So we look. All of these will look at wear rings, stuffing box packing lantern rings with discussed the impeller already. But now we're gonna go through some of them or intricate pieces that you're likely to see on a centrifugal pump. 17. Diffuser: diffuser. Some centrifugal pumps contained diffusers. A diffuser is a set of stationery veins that surround the impeller. The purpose of the diffusion is to increase the efficiency of the centrifugal pump. By allowing a more gradual expansion and less turbulent area for the liquid to reducing velocity, the diffuser veins of designed in a manner that the liquid exit in the impeller will encounter an ever increasing flow area. As it passes through the diffuser. This increase in flow area causes a reduction in flow velocity, converting the kinetic energy into flow pressure. So I have diffuser is essentially doing the same job as the flute casing. In fact, the installation that we're looking at now using impeller in the middle This is pink Item on then we've got a diffuser here. That's these black lines. These black lines are stationary on the diffuser itself looks a lot like an impeller, although the blade will be in an opposite direction to those of the impeller itself. So I noticed that if we go from the impeller outer periphery here, we're moving along to the right, whereas if we go from the other proof for year, we're moving foul going from here on the diffuser, we're moving to the left. So the vein did A diffuser in the impeller are reversed in relation to each other or the direction is reversed in relation to each other. The fellow will be spinning around like this. Fluid would flow out into the diffuser. Andi with increased the pressure not only within the impeller, but also then within the diffuser on our bump, actually, as a veloute casing as well, which is slightly unusual. Conceive using a diffuser, you'll tend to not use a veloute casing. But anyway, if the flow comes out and it'll pastor veloute casing on, we'll get a further increase in pressure. So we got free. Things are increasing the pressure there. The impeller, the diffuser on the veloute casing itself. The fuses are typically used on multistage pumps where you don't want to have a series of veloute cases all next to each other. Multistage pumps are where you have a Siri's off Impeller is all mounted onto the same shaft. Now we'll look at mommy stage comes a bit later on, but essentially in order to have them all mounted on the same shaft, you're going to need to save a lot of space on veloute casings of quite large. So having all of those mounted one after the other 1 to 1 common chef is gonna be a little bit of hard work, and they're gonna take up a lot of space. So I know what it's get around this problem. You use diffuses instead and get rid off the flu casing. Typically, if you've got a diffuser, you won't have a veloute casing. This is very to a multistage pumps. However, I don't see any reason why you wouldn't have that or what You couldn't have that, theoretically, a diffuser Anna Veloute. Although it's less common. I just remember, though, essentially, we're going through what we talked about earlier, that if we can increase the flow path area, then we'll get a reduction in velocity. An increase in pressure will have a look a proper diffuser when we look at our multistage pump later in the course 18. Wear Rings: wear rings. Centrifugal pumps contained rotating impeller is within stationary pump casings to allow the imperative rotate freely within the pump casing. A small clearance is designed to be maintained between the impeller on the pump casing to maximize the efficiency of the centrifugal pump. It's necessary to minimize the amount of liquid leaking through the clearance from the high pressure with discharge side of the pump back to the low pressure or the suction side. So here we can see a diagram of the centrifugal pump. We've got the casing when my mouse is now, and then we got the impeller. Follow a mouse again, but notice on the back of the impeller We've got an impeller wearing ring or in a paella wearing, I know we just say wearing on upon casing wearing the idea off the wearing is that we can reduce the leakage from the discharge to suction side. If we can reduce the leakage, then we have a more efficient. If you have a fully enclosed impeller, then you're going to need a wearing mounted onto the out of rim of the impeller on the suction side, and you're also gonna likely have a casing wearing. What happens is we reduce the clearance as much as possible on these wearing Czar Mawr, less rubbing against each other. There's a fine clearance between them, but you can think of them is just rubbing against each other. That's what you call them. Wear rings. They're disposable or consumable items. By the time the wearing is literally gonna where, away and we need to replace the wearing now, it's a lot easier to replace a wearing on. Abella, then is to replace the entire impeller. NY knew that, but it's also cheaper, so there are some factors to where you reduce wear rings. One of them is to maintain the best possible efficiency off the pump. On the other reason is you want to cut costs because you don't need to replace expensive parts such as the impeller or the veloute casing. There's also another problem with wear rings or problem they send me solve. If you were to put a stainless steel impeller against the veloute casing, which is perhaps also made of some sort of steel, if they were to rub together, you may get something referred to as galling. Galling is when you brought two medals together very quickly and you get micro weld. Now. These worlds can actually quite large, and they can cause the pump to seize now if you use a softer material as the wearing and you won't get steel rubbing on. Still, you have perhaps brass rubbing on steel. If any world and occurs, the wearing will literally break apart or a little bit of its that's welded will break off . It's far better than that occurs. Then you seize the entire pump because of it world into the casing. So that's another good reason to have wear rings installed. Typically, you'll actually heat up the wearing before you put it onto the impeller, because as it cools down, it's gonna shrink onto the impeller itself. Let's just continue on with the lesson here to make sure I'm not repeating something that we discussed later on. Somewhere or erosion will occur at the point where the impeller and the pump casing nearly come into contact. This where is due to the erosion caused by liquid leaking through this quite clearance and other causes as where occurs, the clearance has become larger and the rate of leakage increases. Eventually, the leakage could become unacceptably large and maintenance would be required on the pump so you can see with guy wearing this looks actually like me. Bella wearing would heat that up will push you onto the suction side of the impeller. It'll cool down and then we'll be clamped onto the impeller. You can also screw them onto the Abella. Usual Screw Fred, or you can attach them using threaded screws to minimize the cost of pump maintenance. Many centrifugal pumps the design we wearing rings wearing rings of replaceable rings are attached to the impeller on all the pump casing. To allow a small running clearance between the impeller on the pump casing without causing wear of the actual impeller will pump casing material. These wearing rings are designed to be replaced periodically during the life of pump and prevent the more costly replacement of the impeller or the casing. As I mentioned, you may get wear rings that come into contact with each other, in which case you'll get galling and micro welding. Or perhaps the ring will just wear over time due to erosion. But one thing I didn't mention is that where the wear rings are almost touching each other . Assuming they're in very close contact to each other, you're gonna get some flow between the wear rings. For example, the Abella wearing in the case and wearing on this flow may erode the wearing over time. This is particularly true if you have a very erosive liquid or a slurry on. It's going to flow continuously from the discharge side to the suction side, through the wear rings or through the gap between the wear rings. So it's going to erode away at the wearing is over time. If the clearance between the wear rings becomes too large, you're gonna get a drop in. Efficiency on this could be quite costly. This drop inefficiency might be anywhere up to 4% so this is quite large. When you consider your operator in the pump perhaps 24 7 almost every day of the year, you're effectively paying for electricity to rotate that impeller on 4% off the electricity that your purchasing is wasted energy because you know, actually pumping anything. So it's important that if you do have wear rings, they're properly maintained on that. The clearances maintained as stipulated by the manufacturer 19. Stuffing Box: stuffing books in almost all centrifugal pumps. Rotating shaft that drives impeller penetrates the pressure boundary of the punk casing. It's important that the pump is designed properly to control the amount of liquid that leaks along the shaft at the point of the shaft penetrates upon casing. There are many different methods of sealing the shop penetration of the pump. Casing factors consider when choosing a method include the pressure and temperature of the fluid being pumped the size of a pump on the chemical and physical characteristics of the fluid being pumped so we can see here. We've got a lantern ringed, the packing the shaft. The gland follower on the entire section where the packing is installed, is known as the stuffing box. One of the simplest types of shaft seal is the stuffing box, the stuff in boxes, a cylindrical space in the pump casing surrounding the shaft. Rings of packing material placed in this space. Backing is material in the form of rings or strands that is placed in the stuff in Box two former seal to control the rate of leakage along the shaft. The backing rings are held in place by gland gland is in turn held in place by studs with adjusting nuts as he adjusting not to tightened. They moved the gland in and compress the packing. The actual compression causes backing to expand raid early, forming a tight seal between the rotating shaft on the inside wall of the stuffing box. The high speed rotation of the shaft generates a significant amount he, as it rubs against the packing, brings. If no lubrication cooling are provided to the packing, the temperature of the packing increases to the point where damage occurs to the packing. The pump shaft and possibly nearby pump bearings stuff in boxes will normally designed to allow a small amount of controlled leakage along the shaft to provide lubrication cooling to the packing. The league's rate could be adjusted by tightening and loosening the packing gland. So let's load up freedom model again on. We'll look specifically at the stuff in boxes, all of its main components. So here we are. We're looking at our old faithful centrifugal pump will come around. We can look at the stuffing box stuffing box is the arrangement where my mouse is now for the outline, so it's essentially a space where we can put the packing within the pump casing notice. Shaft penetrates through this side of the packing and also on the other side. The packing itself is a fibrous material, a little bit like rope in some form of grease soap, etcetera in order that it's not very dry, so it's gonna be quite well lubricated. The lantern ring is receiving cooling water. Let's have a look or former cooling from here. So on the back side of the impeller is coming through here, coming down here again. I couldn't liquid. It's going to the land to ring. It's passing through the land of ring through the holes, and then this liquid is being spread out between the shaft and the packing on that is gonna cool on lubricate space between the packing and the shaft. This prevents the packing getting too hot on Ultimately, then, if it gets hot, the lubrication properties that they're packing is impregnated with this sort of grease and fat. That sector that we talked about that's gonna wear away. So if we can keep the temperature down, it's going to prolong the useful working life of the packing. So we'll do that by tool in the packing down you can see we got five layers off packing. So we put a layer in here, All these two on the left. We put another three layers into the other side off the lantern ring. We would have put these, you know, wrap them around the shaft or the space within the stuffing box. I should say on during the installation, they're gonna be sitting quite loosely within the stuffing box area. So in order to get them press and tightly against shaft on also the casing, that is essentially what stops are leakage. Then we're going to use a gland. Follow up. Let's decide from here and you can see on the other side we've actually got him. Not if we try to miss not up on B one on the other side, you can see the screw threads. We're gonna push this clan following inwards into the pump. It's gonna squeeze the packing together, and we're gonna get expanding out radio early. But compressing actually. So actual compression radial expansion. And that means we're going to get a good seal then between the shaft on the casing. However, the problem with packing is no obtaining a good seal. The problem of packing is that when you've attained a good seal, you like me to generate heat. I can tie in the packing up a lot, usually gland follower. But unfortunately, if a tiny out too much I'm going to generate more heat, and if a key tiny off I'm going to generate a lot of heat as the shaft rotates, I'm also potentially going, aware. Aware of the shaft. The packing itself as it becomes hot becomes quite hard, and it's gonna eat away at the chef or it's going to erode the chef. This is not good, because the shaft is quite expensive. So given a choice, I'd much rather replaced the packing than the shaft. So it's very important. Don't over tighten the gland follower on that. You tighten up only as needed. Now, in order to do this, you'll check the leakage rate underneath the gland follower. So around here we can have ah liquid leaking out in this space here, and we'll measure the amount of drops per minute and then in order to ensure that we got the correct leafy, Drake will check out pump manufacturer Manual on. If you got the correct leaky draped, then we just need to maintain that. And over time, the packing will start to dry out and lose some of its ceiling properties. So in order to combat this on, get a good seal again, we're gonna tighten up the gland follower even more so Just imagine, for a moment we installed the pump. We tightened up the gland follower. We ran a punk on. We notice under here that the leakage rate is, for example, 15 drops per minute. So we go away and a month later we come back. When we measure, the leakage rate is being 50 drops a minute. Now, this is too much. We've got too much leakage. So we tighten our clan follower and it will compress the packing. Still further on will get leakage rate back down to 15 drops per minute. We can keep repeating this process, but at some point, the properties that allow the packing to seal, such as this soap, in fact, that we talked about are gonna wear away. And when they're worn away, it doesn't matter how much we tightened up the gland follower. We're not gonna be able to get a good seal on. Also, we're gonna be generating quite a lot of heat, so we need to replace the packing. At that stage, the heat itself is gonna be absorbed by the casing. And if the bearings amounted nearby, some of that heat may also transfer to bearings and damaged bearings. So it's very important that we replaced the packing when we're supposed to replace it on. We also need to keep our leaky Dre or run off rate through the packing to the correct amount. For example, 15 drops per minute if it's not possible to cool the packing using the process liquid, as we saw here with just drawn out process liquid from this side for this space here. If we can't do that, then we're going to need to find external source for a cooling liquid. The reason we might not be able to draw the process liquid directly to the lantern ring is because it simply may not be on appropriate liquid. If we're pumping something corrosive or erosive or something that has a very high temperature, then there's no point passing that through the space between our packing and our chefs so we'll set up on external cooling liquid source on. Then we'll use this to transfer liquid to slandering on, then to the packing. I should also mention that the packing itself here is writing directly on the shaft. However, that may not be always the case. As I've mentioned previously, packing might get quite hot, and then it will become quite hard, and it's going to erode the chef. So what we'll do, we'll actually put sleeve on the shaft. And you can think that this has been a large wearing so long sleeve. It's it's between the packing and the chef on overtime. If the backing does start to heat up and become very hard, it's gonna wear the sleeve away, which is sacrificial instead of the shaft. This means that we can replace the shaft sleeve, which costs very little instead of replacing the shaft itself, which costs a lot. So that is a central fuel pump, compression packing or more commonly referred to as the centrifugal pump packing 20. Lantern Ring: in this lesson. We'll look at the lantern ring, so we're going back over the ground. We covered in the previous video a little bit, but it's quite a short lesson, so I think it's worth doing. Lantern ring. It is not always possible to use a standard stuff inbox to seal the shaft of a centrifugal pump. The pump suction maybe under a vacuum so the outwards leakages impossible or the flu. It may be too hot to provide adequate cooling of the packing. These conditions require modification to the standard stuff in box. So here we can see Atlanta ring and see where the food would come in and go through these holes or four holes on this lantern ring looks like it's manufactured from stainless steel . One method of adequately cooling the packing under these conditions is to include a lantern ring. Atlantan ring is a perforated hollering located near the center of the packing box that receives relatively cool, clean liquid from either the discharge of the pump or from an external source on distributes, illiquid uniformly around the shaft to provide lubrication and cooling the fluid enter in the lantern. Rincon cool the shaft, unpacking lubricate the packing or seal the joint between the shaft and packing against leakage of air into the pump. In the event the pump suction pressure is less than that of atmosphere. So as discussed previously, the lantern ring is allowing a cooling fluid to pass to the packing, and that allows us them to cool the packing and to lubricate the space between the packing in the shaft is quite important piece because without the Lanson ring, we wouldn't be able to lubricate and adequately cool the packing if we can't take the cooling liquid from the process liquid itself. In other words, if we use in fresh cool water or Sweetwater moderate temperature, then we can just use that water to cool down the packing. And that's not a big issue. If we using the pump for a sewage treatment plan for a serious treatment process, then we're not going to be able to use the sewage, which is perhaps raw to lubricate the packing. So in that case, we're gonna have to find an external cooling liquid, and we might just tap this straight off our fresh water connection nearby, or perhaps will use a different cooling fluid such as oil. It really does depend on the process, though, on what is acceptable to use. Obviously, using oil has its own problems, especially concerning environmental pollution. So whatever oil you're using to cool the packing and lubricated, you're gonna have to try and recapture that, or to put it into a storage area rather than discharges straight to a river or the environment. So as a ways is always different elements that we need to be aware off on different systems , we need to be aware off in order that we can better manage the pump itself. Another consideration here is that if we're tapping directly onto a fresh water connection and we can assume we're always gonna have a three bar of pressure supply or a constant supply of pressure, however, if we using something else, such as an oil cup or some other source, then we may have to replenish that source periodically. That means someone's gotta go around and pour oil into the oil cups or the oil reservoir on this oil then leaks down into the packing. If somebody forgets to fill up the oil cup, then obviously you've got no lubrication cooling you're packing will burn away on. Then you'll have to change it, or at least shut down the pump so effectively you've got downtime. I should also mention that I talk about water has been cooling and lubricating fluid, but you may also have kerosene or steam or oil or any other number of things that you may be using to call and lubricate the packing. So it really does depend on the system served. So keep that in mind, you know, always gonna be using water you may be using a dose of steam on that dose of steam may be used to clean the packing or to get rid of anything that may have settled on the packing on may be causing it not to seal correctly. If we're piping a cooling liquid to the pump, you'll often hear people talk of flush. Systems on were effectively flushing out the packing, so we're sending a cool, clean liquid to the stuffing box on. Be real cool that a flush system or a flushing liquid 21. Mechanical Seal: as I mentioned previously, there are alternatives to using packing on. The main alternative available is called a mechanical seal. Where is packing? Use very old Mechanical seals are relatively new. Let's just have a really food lesson now and then we'll take a look at a mechanical seal, and I'll briefly explain how it works. Mechanical seals in some situations, pack unity released. No adequate for sealing the shaft. One common alternative method for sealing the shaft is with mechanical seals. Mechanical seals consists of two basic parts. A rotating element attached to the pump shaft on a stationary element attached to the pump casing. Each of these elements has ah, highly polished sealing surface. The Polish faces of the rotating and stationary elements come into contact with each other to former seal that prevents leakage along the shaft. So mechanical Seal is doing the same Job was packing, although it looks totally different. Andi functions in a totally different manner, so let's just load up a free D model of a mechanical seal. So here is our mechanical seal. Still a little spin. As you can see, we've got a number of different parts that make up a mechanical seal. We've got a primary ceiling face, which is probably the most important bit on that is around here and around there on the other side. We got another prime receiving face and then we've got a stationary seat or estacion. Lucille, that's actually gonna be this one on the right. And then we got the seal that rotates, which is this one on the left. The material that the ceiling faces are made out off or the material the primary seals made out off this one Here on on the opposite side. This material is gonna be very, very hard. It may even be tongue stone or some form off ceramic on. I'll tell you why we choose our material for that in a moment with singularity. China Spring on another spring, retained on the end or back plate. So what's gonna happen here? You see, Impeller is gonna be installed on the left. This PC is going to go into our pump casing. So actually, just going toe push that into a recess in the pump casing is going to sit there. Sometimes it'll lock in place to have a locking pin or a weird shape that stops it rotating . So that is a stationary ceiling face on the opposite side. We gotta have rotating ceiling face. This one rotates with the shaft as the shaft rotates. And then we got a spring which is used to maintain a constant pressure from the back of the impeller onto the to ceiling faces. So as the shaft is rotating, it's just imagine the chef runs through here for the middle of the mechanical seal. So straight down there as the chef is right, tasing this Syrian face here is gonna spin on the one the right is gonna be stationary on the impeller, which may move back and forth slightly or from left to right due to axle loading. Some of that movement is gonna be taken up by the spring, and the spring is going to ensure that the ceiling faces are always pressed together so normally that we pressed together. And if the impeller slides a little bit to the left, or if the whole shaft moves to left or right slightly, we're still gonna have enough pressure to push these two ceiling faces together. So keep that in mind. You fellas here on the left will clamp it all together on the spring, maintains the pressure pushing the seats or this evening face the primary season face together. When the primary ceiling faces have pushed together, they have a very, very, very, very, very, very small amount of clearance between them. And what's gonna happen is, as the rotating part of the mechanical seal spins is gonna rotate very fast on any liquid that leaks between the prime resealing faces. He's going to more or less evaporate. It's gonna be heated up on. Then it's gonna evaporate, and we're not going to get any visible leak each through mechanical seal. Notice that I said, we're not going to get any visible leakage. It's not that the mechanical seal is not leaking. It's just that you can see it as the tiny amount of process liquid gets between the primary sealing surfaces. It's gonna evaporate, so we're not gonna see any leakage. Mechanical seal itself is leaking to some degree, but you just don't notice it. And it's a very small amount. Big benefit with a mechanical seal compared to packing is that we're not damaging the shaft . We don't generate any heat. As a rule, mechanical seals last a lot longer than packing does, however, there's simply no, it's cheap packing. If you get a problem, you can just replace it. Whereas Mechanic pursues, you can also replace them, but they're a lot more expensive. The other problem in mechanical seals, which you may sometimes see or experience, is that if you get anything on the primary ceiling faces, they're gonna leave. So you have to be very, very careful when you're installing mechanical seals in order you don't get any leak it on . I mean, really, really, really careful. The primary ceiling service is a very hard, so it's quite difficult to scratch them. However, if you get a small amount of dust or perhaps a hair that runs across the ceiling faces or just about anything else, you're gonna get leakage. So when you're handling mechanical seals and when you're installing them, they have to be immaculately clean, installed them a few times, and admittedly that have leaked. And it's been very frustrating because you have to then disassemble the entire pump, which may me and you need to remove the pump in order to check the seal again or replace it so you're gonna be very careful when you're installing these mechanical seals. If you have a leakage with packing, normally should just try in the packing up and it solves issue. That's not the same of the mechanical seal. So keep that in mind, however generally if they're installed correctly, which they always should be, then you're gonna get a youthful working life out in the kind of Basile, which probably far exceeds what you would get with packing. And you're also not gonna get source where you may get a high temperature rise or damage on the chef, etcetera. So there are a number of advantages with mechanical seals. But as with everything in life, if engineers know that it's a good solution, but it costs a lot more initially, then they always advocate for using it. However, a purchasing department who only sees the initial cost will tend to go for the cheaper option, which is gonna be packing 22. Centrifugal Pumps Summary: centrifugal pump summary. The important information in this chapter is summarised below. Thean Pellet contains rotating vanes that Empire Radial Rotary motion to the liquid. The veloute collects the liquid discharge from the impeller, acquired velocity and gradually causes a reduction. The fluid velocity by increasing the flow area, converting the velocity head to a static head. A diffuser increases the efficiency of the centrifugal pump by allowing a more gradual expansion in less turbulent area for the liquid to slow as the flow area expands, packing material provides a seal in the area where the pump shaft penetrates the pump casing wearing rings, a replaceable rings are attached to the impeller on door, the pump casing to allow a small running clearance between the impeller and pump casing without causing wear of the actual impeller pump casing material. The lantern ring is inserted between brings packing in the stuffing box to receive relatively cool, clean liquid on distribute a liquid uniformly around the chef to provide lubrication and cooling to the pattern. So that's essentially what we've just learned. When we were looking at each of the components of a centrifugal come in the next section, we're gonna learn a bit more about how you can operate the pump successfully on how you can identify problems with centrifugal pumps, such as when a pump is capitated. If you know entirely comfortable with the components of a central figel pump or what each bite is doing, then an adviser just to go back, perhaps in a week on doing other refresher on, you'll find that if you do a refresher in a week's time, just watch the videos again on then. Perhaps a month later, the information that you're absorbing will really start to stick Andi. After that, you should be fine. You should be able to remember pretty much everything that you've learned for at least the important bits on. Then you'll be able to apply that knowledge so it's going with the next section. I hope you're enjoying the course thus far. If you got questions or comments, please do send them off to me on more than came to answer any questions you may have. I never pretend to know absolutely everything about engineering. I've also got a lot of stuff that I need to learn, and whenever people ask me questions, it's a good chance for me to check If I really do know what I'm talking about. Really do appreciate it. Anyway, let's get on with the course. 23. Centrifugal Pump Operation: so, as mentioned previously in this section, we're going to look at how you can successfully operate the centrifugal pump and also how you can identify problems with a centrifugal pump. So let's get started. Centrifugal pump operation Improper operation of centrifugal pumps can result in damage to the pump and loss of function of the system that the pump is installed him. It's helpful to know what conditions can lead to pump damage, to allow better understanding of pump operating procedures and how the procedures aid the operator in avoiding pump damage. So if you don't maintain the centrifugal pump correctly, there's a chance that you might get downtime on. If there's one thing that every engineer hates, and especially the guys in accounting, it's downtime. So if you can operate the pump successfully for a long period of time, on it reaches its next maintenance interval. Then you can assume to your practices. Best practices on a pump itself is gonna have a long, useful work in life 24. Introduction to Centrifugal Pump Operation: introduction to centrifugal pump operation. Many centrifugal pumps are designed in a manner that allows the pump to operate continuously for months or even years. These centrifugal pumps off the rely on the liquid that they are pumping to provide cooling and lubrication to the pump bearings on other internal components of the pump. If flow through the bumpy stop while the pump is still operating, the pump will no longer be adequately cooled on. The punk can quickly become damaged. Pump damage can also result from pumping a liquid whose temperature is close to saturation conditions. Saturation conditions here are usually referring to when you reduce the pressure of a liquid on, then it becomes a vapor or a gas. I should say so. Keep that in mind. I'm going to refer to that also later on in the course. But yes, do keep in mind that when you're pumping a liquid, the pump manufacturer may have accounted for the fact you're pumping that liquid on. They're gonna shoot that liquid flowing through the pump of removing some of the heat generated by the pump. If the pump is in operation and it's pumping nothing, then it will have a tendency to get hot and the motor as well. However, it's very easy to identify when you're no pumping using the centrifugal pump because you simply won't have any discharge pressure or a very small amount. 25. Cavitation: capitation. The flow area at the eye of the impeller is usually smaller than either the flow area of the pump, suction piping or the flow area through the impeller vanes. When the liquid being pumped enters the eye of a centrifugal pump, the decrease in flow area results in an increase in flow velocity, accompanied by a decrease in pressure. The greater the pump flow rate, the greater the pressure dropped between the pump suction on the eye of the impeller. If the pressure drop is large enough, or if the temperature is high enough, the pressure drop may be sufficient cause a liquid to flash the vapor When the local pressure falls below the saturation pressure for the fluid being pumped. Any vapor bubbles formed by the pressure drop in the eye of the impeller swept along the impeller vanes by the floor of the liquid. When the bubbles enter a region where local pressure is greater than saturation, pressure father out the paella vein, the vapor bubbles abruptly collapsed. This process of the formation and subsequent collapse of vapor bubbles in a pump is known as capitation. We can see that actually going here increased static pressure we're gonna have stage 1234 and then you're gonna have a collapse off the bubble itself. And this is capitation affecting a vapor bubble. Let's read through the entire lesson, and then we'll go back and discuss this in more detail. Capitation in the centrifugal pump has a significant effect on pump performance. Capitation degrades the performance of a pump, resulting in a fluctuating flow rate and discharge pressure. Gravitation can also be destructive to pumps internal components. When a punk cava Tates vapor bubbles forming the low pressure region directly behind the rotating impeller vanes these vapor bubbles and move toward the oncoming impeller vein where they collapsed because of physical shock to legion edge of the impeller vein, This physical shock creates small pits on the leading edge of the impeller vein. Each individual pit is microscopic in size, but the cumulative effect of millions of these pits, formed over a period of hours or days, can literally destroy a pump. Impeller Oh, gravitation can also cause excessive pump vibration, which could damage from bearings, wear rings and seals. A small number of centrifugal pumps are designed to operate under conditions where capitation is unavoidable these pumps must be specially designed to maintain to withstand a small amount of capitation that occurs during their operation. Most sent fuel pumps are not designed to withstand sustained capitation. Noise is one of the indications that sent for your pump is capitated a capitated pumpkin sound like a can of marbles being shaken? Other indications that can be observed from a remote operating station of fluctuating discharge. Pressure flow rate on pump motor current. I should actually say have fluctuating Puntland's current. But if you've got capitation, it's so extreme that it sounds like a kind of marbles being shaken. Then you really do have problems. Capitation is a big, big, big, big no no. You'll also hear people talk about capitation is when they're talking about propellers on a ship. If you get capitation on a propeller, worship, the capitation effects will gradually more or less. Eat away at the propeller on. This gives you a result. Drop in efficiency. On this drop, inefficiency could be quite costly. Imagine that you are on a ship and you want to sell across the Pacific Ocean. Let's say, on a container ship 50,000 tons. You start off on the West coast of America, and you want to go to Japan. So you're looking at around 10 14 days of travel, probably 14 days now. That is a lot of travel 24 hours a day, seven days a week for two weeks on. If you've lost, imagine 234% of the efficiency on your propeller, the Nats 234% of additional cost over time. This could be considerable. So it's important that if you have capitation on the propeller or the impel off, you really need to take care of it on solve the issue as quickly as possible. With the pump, you can look at it in the same manner if you got capitation on the impeller or on the pump itself. Then over time you're gonna get a drop in efficiency on your more or less throwing money away. Because if you've got a 4% drop in efficiency, you're incurring the same cost, but you're getting less work out so economically, it's a bit of a disaster. However, let's go back and have a quick look. Capitation as we worry mentioned, capitation is effectively where you get a bubble or a gas bubble behind the impeller. Why, as it travels through the impeller, you're going to get an increase in pressure and a reduction in velocity. This bubble is then going abruptly collapse. And if it collapses next to the impeller, it's gonna take a tiny bit of vessel with it, perhaps, or gonna cause damage to the metal on overtime. If you multiply that by millions of bubbles, you're going to eat away at the impeller and it does literally looked like that. It looks like somebody's bitten little bits out of the impeller, so it's not a very nice thing to look at it. It's very easy to identify when you've got capitation, especially when you're maintaining the pump. No, only you couldn't get physical damage on the impeller, which gives you a drop in efficiency. You're also going to get perhaps excessive vibration, which is going to stress the bearings on the wear rings on this again is an additional cost . If you need to take the pump apart, replace all of these parts if you're looking to identify capitation and yet noise is one of the big factors, you may be able to do things such as condition. Monitoring like vibration analysis of the pump that will probably pick up gravitation. An early stage. You're also going to be able to see a fluctuating discharge. Pressure fluctuated flow, rape and fluctuating motor amps. If you have a nap gauging stored on the motor than your belt to see jumping up and down slightly When the motor is running consistently, you should have a relatively consistent amount of them's when you start the motor. Initially, you often see that the amps jump up to six or seven times their normal load. Current. This is acceptable. However. The AM pH will drop back down over time, and when the pump is running normally, it's gonna consume a normal amount of amps. So start up six or seven times for low current on. Then, when it's running back down to normal operating condition or normal low current so that capitation if you ever get capitation and I do advise you to try and take care of it as quickly as possible. Obviously, sometimes this isn't possible, but in the next lesson, we're going to look at how you can treat capitation, or at least reduce its effect until you can maintain the pump 26. Net Positive Suction Head: net positive suction head in this lesson. I'm actually going to just briefly go over the first section this bit here. Andi are not going to go into the theory too much. I'm just going to try and explain. A couple of concepts on them will apply that in the next lesson. Net positive. Suction head to avoid capitation, centrifugal pumps the pressure of the flu it'll point within the punk must remain above saturation pressure. The quantity used to determine if the pressure of the liquid being pumped his adequate to avoid capitation is the net positive. Suction head or MPs hatch the net. Positive suction had available MPs age. A. It's the difference between the pressure of perception of the pump on the saturation pressure for the liquid being pumps net positive suction had required MPs page are is the minimum net positive suction head necessary to avoid capitation. The condition that must exist to avoid capitation is that the net positive suction had available must be greater than or equal to the net Positive suction head required. This requirement can be stated mathematically is shown below, So in order to avoid gravitation, we need to have an MP s age pay that is greater than an NPS H r. Now don't go further through this lesson because I think goes into a bit too much detail for an introduction course. But the most important thing you need to realize here is that the net positive suction had available MPs, Age A is the difference between the pressure on the suction side upon on the saturation pressure for the liquid being pumped. Remember that if we're approaching saturation pressure, we're going to allow the liquid to turn into a gas or of a pra on. This means we're gonna get capitation if we've got no gas bubbles within a flow within a liquid in trained within our liquid, I should say then we can't have capitation. As soon as we get bubbles, we can have capitation. So we've always gotta maintain the difference between the suction side of the pump and the saturation pressure of the liquid. The net positive suction have required MPs. H r is the minimum net positive suction had necessary to avoid capitation. In other words, if we can keep MPs h a above NPS age are we're not going to get capitation. That's all. When you take away from this lesson because MPs A, J and I, it's quite lot taking. But just remember that if you can keep the net positive such ahead available greater than the net positive suction had required, you will be able to avoid capitation, so that's the most important thing from this lesson. 27. Preventing Cavitation: preventing capitation. If a centrifugal pump is capitated, several changes in the system designer operation may be necessary to increase the MPs. Hate a above the MPs age are and stop the capitation. One method for increasing the MPs A. J is to increase the pressure of the suction side of the pump. For example, if a pompous taken suction from an enclosed tank are the raising the level of the liquid in the tank or increasing the pressure in the space above the liquid increases suction pressure. What I'm gonna do for our this lesson is just explain each of these paragraphs as we go through, because otherwise it's quite a lot to take in. So we already know that if we can increase nps h A and keep it above nps h r, then we're going to avoid capitation so effectively in order to avoid capitation or if we've got capitation and we want to reduce the gravitation, we're gonna look at raising the NPS page A. So we know that if we can increase the suction pressure, then we're going to raise the value of NPS age A. So how are we gonna increase that? Such a pressure. Well, one way we're gonna be able to do it as seen in this example Here. We've got a closed tank on as we are drawing the liquid and we're gonna have a certain amount off pressure. However, if we raise the level of the liquid in the tank, then we're going to have a greater pressure due to the weight of the liquid acting on the liquid itself on this is going to raise that nps hate? A. So if we raise the level of the liquid in the tank, we increase the MP s A J or alternatively, if we can't raise the level in the tank, maybe we can connect a pressure vessel to it. Or a pressure source. Imagine we connect to bar of Compressed there and we pressurize the entire tank. I'm not saying that you should do this, but just keep in mind. So we pressurize the top off the tank, and this gives us a pressure on top of the liquid on this. Pressure is exerted through the liquid on. It also raises our MP S H A. Keep in mind, there are seven pressurized tank, but this is not something you would normally do on a day to day operation unless the tank specifically designed to do this in order to add pressure to a tank or to apply a press to the tank, the tank itself needs to be a rated pressure vessel. There's a lot of laws and governance around pressure vessels and when you can and can't use them and after what pressures. So I don't just go around pressurising tanks if you don't know what you're doing. So just a bit of a disclaimer there. In this course, it is also possible to increase the MPs age A by decreasing the temperature of the liquid being pumped, decreasing the temperature of the liquid, decreases of saturation pressure, causing the MP S H A to increase. So we've already seen gave increases suction pressure in pshh rises and then we increase in B s, A. J, which overly puts us above nps h r. However, if we reduce the temperature of the liquid being pumped, weaken create the same trick again, we increase nps A J, which hopefully puts us above and be shr. And this means we will have no capitation if the head losses in the pump such and piping can be reduced. The MPs A J will be increased. Various methods for reducing head losses include increasing the pot damage, sir. Reducing the number of elbows, valves and fittings in the pipe and decreasing the length of the pipe. So in this example, here, I'm just gonna pick one of these. Increasing the plight, dammit. Same again. The Bernoulli effect increased the area reduction in velocity. Increasing pressure on this increasing pressure gives us a higher nps A J and hopefully that will put us above nps h r on. Then we will have no capitation because we're not gonna get any gas bubbles of forming. It may also be possible to stop capitation by reducing the MPs HR for the pump. The MPs HR is not a constant for a given pump under all conditions, but depends on certain factors. Typically, the MPs HR pump increases significantly as the flow rate through the pump increases. Therefore, reducing the flow right through the pump by frightening a discharge valve decreases the MPs HR MPs. A jar is also dependent upon pump speed. The faster the impeller pump rotates, the greater the MPs HR. Therefore, if the speed of a variable speed centrifugal pump is reduced. The MPs HR of the pump decreases. However, since it pumps flow rate is most often dictated by the needs of the system on which it is connected. Only limited adjustments can be made without starting additional parallel pumps if available so we can regulate the MPs HR by more or less fraught Erling the disguise valve on the discharge side of the pump. When I say falling falling is where you move the valve handle position anywhere between fully open and footed closed. So if you regulate the discharge valve, if we close it slightly, then we're gonna get a reduction in MPs H r. Same again. If we can reduce MPs HR below en psh a, then we're gonna have no capitation. Important to remember, though, that when you're throttling the flow for a pump, you can only do this so much before you have an effect on the system. If the centrifugal pump is being used for cooling applications, then when you reduce the flow, you're going to reduce the amount of cooling that is being supplied to the process. If you reduce the amount of cooling that is supplied to process that it may be that the process itself needs to slow down. So, for example, if I got a nuclear reactor and I'm supplying to the water to the nuclear reactor, if we're generating X amount of electricity than we need, why amount of cooling? However, if I reduce the amount of cooling, then I can no longer generate that much electricity because I'm generating too much heat. So the whole power station has to reduce the amount of electricity that's being generated because I can no longer cool down the nuclear reactor, so it has an effect. And cooling water pumps are often centrifugal pumps because they are very good for handling relatively clean fluids such as fresh water or river water that's been treated etcetera. So keep in mind, yes, you can regulate the flow through the pump in order to reduce MPs HR, but only to a certain point. And then at that point you're going to need to start on an additional pump to maintain an adequate flow rate. But just to recap, in fact, before we recap, let's just finish the lesson. I'll go for again on do a very short summary. The net positive suction have required to prevent capitation is determined. Free testing by the pump manufacturer on depends upon factors including the type of impeller, inland impeller design, pump flow rate, impel of rotational speed on the type of liquid being pumped. The manufacturer typically surprise curves of MPs. Age are as a function of the pump flow rate for a particular liquid, usually water in the vendor manual for the pump. The reason that they did a test on water is simply because water is a very good reference point. If you were using sea water, which you could say seawaters arguably easier to get because there's much more off it. But unfortunately, the salinity amount of salt within the sea changes depend upon location. So if you're taking a sample from the Mediterranean Ocean and used as a reference point, the salinity is gonna change when you compare it to, for example, the Pacific Ocean. When you change the solemnity or if you varies, then that means you've got a different amount dissolved salts on this ultimately means that the water has a different density. That's why on ships, sometimes you'll see something called a plum cell line on the lips of line is more or less there to say how much you can load the ship depending upon the different densities of the water. In other words, depending upon the salinity of the water. So let's just go up. Will do very quick recap. We've got to keep MPs h a above MPs h r. We can do this by increasing the level of liquid in the tank, for example, on the assumption side, or by applying a pressure onto the top of the liquid in the tank. Or we can pressurise the tank. We should say we can also change the pipe work to the pump itself, such as increasing the part damage on assumption side, reducing them rive elbows, changing the types of valves or fittings, etcetera. Some valves have larger pressure drops and others a gate valve, for example, as a very low pressure drop and would be ideal for a centrifugal pump. In some respects, however, a globe valve which has a larger pressure drop, may not be the best type of valve to install on the suction side of a pump. If we go on the opposite side rather than try and raise the MP S, H A and well drawn reduce MPs a jar instead, and we can do that by regulating the flow. So we've got a couple of things here. Reduce the temperature, regulate the flow through the pump, reduced the impeller velocity. All of these options that we can use to reduce capitation. You'll notice also here that we talk about variable speed. A variable speed centrifugal pump is a type of pump. They use the frequency drive, sometimes called a variable speed drive or VSD on were just a frequency in order to regulate the speed of pump. These types of pumps are quite useful in some respects because it means you can slowly start the pump on. We don't get a huge increase in AMP it when we start the pump, but it also allows us to regulate the flow through the pump. So rather than having a simple on off pump where we are producing the maximum flow rate or no flow, we can regulate the flow through the pump. And generally this is a lot better than if we just simply have a non or function. So that's another way we can reduce the MPs HR on hopefully keep the MP S h a above MPs HR . That's as much as I want to cover in this lesson. I appreciate it a lot to take you. There's a lot of terms being thrown around in this lesson, but hopefully it's clear. If not, then shoot me a message and I'll try and break this lesson down into different components on Maybe that will make more sense going forward. 28. Centrifugal Pump Characteristic Curve: central few upon characteristic curves for a given centrifugal pump operating a constant speed. The flow rate for the pump is dependent upon the differential pressure or had developed by the come the lower the pump it, the higher the flu. Every a vendor manual for a specific pump usually contains a curve of pump flow. Rape versus pump Head called a punk characteristic curve. After a pump is installed in the system, it is usually tested to ensure that the flow rate and the head of the pump are within the required specifications. A typical centrifugal pump characteristic curve is shown below. There are several terms associate with the pump characteristic curve that must be defined. Shut off head is the maximum head that could be developed by centrifugal pump. Operating a set speed don't run out is the maximum flow that could be developed by a central pump without damaging the pump. Centrifugal pumps must be designed and operated to be protected from the conditions of pump right now or operating it shut off head. So here we've got a pump curve, and essentially what we're looking at is the maximum flow we can have out of the pump is the pump run out without damaging the pump on the maximum pressure that we can achieve from the pump on this is referred to as the shut off head. So pressure on the Y axes and flow on the X axes normally will say, Okay, we want a specific pressure, Let's say four bar on, we need a certain outflow and then we'll go along the line here on, We'll find out what I flow would be at a certain pressure or vice versa. If we have a certain flow rate, what are pressure should be. So that's what we're using a pump curve for. If you want to think about this a different way, you can think of the shut off head as being a very long pipe that comes out of discharge side of the pump, and it goes up vertically at some point, the liquid being pumped upwards vertically through the pipe. He's no longer going to rise upwards vertically, and at that point we've reached their shut off head. So in other words, if we have a point that goes up vertically, 10 meters on the pump pumps up to a height off, say free meters, then that is shut off. Hit the pump cannot pump the liquid any higher on the other end. You we got pumped, run out and this is our maximum flow rate through the pump that we're gonna get before we start damaging the pump. As flow increases, the pressure decreases. As the pressure increases, the flow decreases. So there's a relationship between the two, as I've already mentioned, if we had a very long vertical pipe connected to the dish outside of the pump when we reached the shot off head, all we're going to see is the liquid not moving anymore. It's just gonna be under a certain amount pressure. Let's say it's gonna be free meters into the discharge pipe all three meters in height, and it's not gonna move anymore. If we shut off the pump, the liquid will drain back down again under its own weight. On, if the pumps primed and return it back on again, it's going to reach up to free meters in elevation again because that is it Shut off head. But notice that when we read the shut off head, there's no flown on. We can see that also on the punk curve. You shut off head. No flow on. As the flow increases, the pressure will decrease. So that's why punk characteristic curve is used for, although people just call them pump curves. 29. Centrifugal Pump Protection: centrifugal pump protection. The centrifugal pump is dead headed when it is operated with no flow through, for example, with a close discharge valve or against a CT check valve. If the discharge via was closed and there is no overflow path available to the pump, impeller would turn the same volume of water as it rotates in the pump casing. This will increase the temperatures a liquid due to friction in the pump casing, to the point that it will flash the vapor. The vapor can interrupt the cooling flow to the pumps, packing and bearings, causing excessive wear and heat. If the pump is running this condition for a significant amount of time, it will become damaged. When a centrifugal pump is installed on a system such that it may be subjected to period, it shut off head conditions. It is necessary to provide some means upon protection. One method for protecting the pump from running dead headed is to provide a recirculation line from the pump discharge line upstream of the discharge valve back to the pump supply source. The recirculation line should be sized to allow enough flow through the punk to prevent overheating and damage to the pump. Protection may also be a complete by use of an automatic flow control device. Centrifugal pumps must also be protected from run out. Run out can lead to capitation and can also cause overheating of the pumps motor due to excessive currents. One method for ensuring that there is always adequate flow resistance at the punk discharge to prevent excessive flow through the pump is to place an orifice or a throat a valve immediately downstream of the punk discharge. Properly designed piping systems are very important to protect from run out, so let's go back up to the top will work away down again. So we're talking here about one term, which is called dead Heading or sometimes dead headed. A dead headed pump is a pump that is discharging to a closed discharge. In other words, we're running the pump were trying to discharge the liquid, but unfortunately the discharge valve is closed. And so the impeller is just spinning. We're maintaining the pressure, but the discharge valve is closed, so we're just recirculating or returning the water that is in the casing. So that's when we are dead headed or when we are dead heading the pump. Occasionally, it might be that we have to run the pump periodically. Dead headed on in this case will have a recirculation line, which goes from the discharge outside of the pump. Back to the assumption side on this means we're not joining the same liquid over and over again within the case in Iraqi, circulating the liquid for a small circuit on this prevents a liquid from overheating or becoming too hot right now is where we have a situation where the flow through the pump is excessively high. And this can happen when we have a very lives discharge pipe on. In order to avoid this, we want to reduce the size of the discharge pipe or put an orifice within the pipe in order that we can reduce the flow rate for the pump. So one term is called run out. That's where we have a very excessive flow right through the pump, and we try to reduce that by throttling valves or installing a or AFIS, etcetera. On another term that we need to be aware off is called Dead heading with dead headed, and that is where we operate the pump with the discharge valve closed or where we operate. A pump on the pump cannot discharge liquid on. This means that returning the liquid within the pump, I actually have one instance where we left to send fuel pump running on. We must have left it running for quite some time because the fresh water that we had within the pump was turned so much that it actually turned to steam and we blew discharge and suction pressure gauges such and discharged gauges are usually mounted just before or after the pump on the liquid got that heart that it turned to vapor or steam on. Then we shattered pressure gauges, so that shows what can happen when you're totally dead. Heading the pump. I shoot in this situation I remember fully, but I imagine both the suction and discharge side off the pump were closed, and we re literally just rotating the impeller with a small amount of liquid, and we hear the liquid up until it turns to steam on This steam ultimately caused, our board engages to shatter 30. Gas Binding: gas binding gas binding of a cent fuel pump is a condition where the pump casing is filled with gases or vapors to the point where the impeller is no longer able to contact enough fluid to function correctly. The impeller spins in the gas bubble but is unable to force liquid through the pump. This can lead to cooling problems for the pumps packing and bearings. Century re pumps a design so that pump casings air completely filled with liquid during pump operation. Most think fuel pumps can still operate when a small amount of gas accumulates in the pump casing. But pumps in systems containing dissolved gases that are not designed to be self venting should be periodic, prevented manually to ensure that gases do not build up in the pump casing. A gas binding is essentially where we don't have enough liquid within the Centerview upon in order to get a suction on to pump liquid. When we talked about simply re pumps, you have to imagine that the liquid is within the pump is essentially a working part of the pump itself. If we don't have any liquid within the pump, then we cannot use the impeller to pump centrifugal pumps and no self prime ing. That means they can't pump gas before they pump liquid. They need to be primed with a liquid in order to function correctly. So if we have gas in a centrifugal pump, then we simply won't get enough suction or ahead of suction in order to pump the liquid. That's one reason why century well pumps a normally mounted below the liquid being pumped or whenever possible. That's what we choose to do, because that means we've always got a positive head of pressure on the substance side. If a tank is mounted higher up, or if liquid is higher up than the pump, the liquid will flow down due to gravity. Andi is gonna fill up the pump casing on our pump is m primed. If we use in the centrifugal pump on the liquid being pumped is below the centrifugal pump , then we have to have enough suction pressure to draw that liquid up and into the pump. If the pump is not primed, then you simply will not have that negative pressure. It won't be possible. You have to prime the pump first. If you've got a century of a pump that is mounted above the liquid being pumped, you'll often have a prime, a pump on the prime in pumps. Job is literally to draw the liquid up to the pump in order to prime the centrifuge upon. And at that stage, when it's primed, you can start the centrifugal pump. The prime and pump itself is going to be what they call a positive displacement pump. We're going to cover that in a different course. So if you like, of course, about centrifugal pumps and advisers to check out the course on positive displacement pumps as well. So just keep that in mind. No, you cannot pump the gas with the centrifugal pump is in my mind it's biggest weakness positive, despite pumps kampung gases. But they have other little intricacies that makes him quite interesting as well. And one of them is that if you shut discharge valve, in other words, if you deadhead positive displacement pump, you'll get an ever increasing pressure on. This is one reason why you always need to have a safety relief valve on a positive displacement pump. Where is the centrifugal pump? You don't need to have a safety really felt 31. Priming Centrifugal Pumps: prime ing centrifugal pumps, most centrifugal pumps and not self prime ing. In other words, the pump Casey must be filled with liquid before the bumpy started. While the pump will not be able to function is the pump casing becomes filled with vapors or gases? Pump impeller becomes gas bound and incapable of pumping to ensure that a centrifugal pump remains primed and does not become gas bound. Most interviewer pumps located below the level of the source from which the pump is take consumption. The same effect can be gained by supply liquid to the pump, suction under pressure supplied by another pump placed in the suction line. So it's essentially just going back to what we talked about. In the other lesson, you have to have a liquid in the pump in order for it to work, and that's what we call it Primed pump. What's also interesting is that once you've pumped out certain volume of liquid, if you should suddenly not have the liquid there anymore. So let's imagine that the pump is primed. But the pipe after the pump or before the prom story on the suction side is not primed. There's no liquid there. Then you'll effectively pump the liquid out of the pump, and it will continue on its way along the discharge piping. Now, if it continues along its way, there's a chance it may draw in more liquid into the pump. However, there's also the chance that won't be enough suction there to draw in more liquid. Another way. Think of this very basic example is Imagine that you want empty the fuel tank on a car so you'll put a hose into the fuel tank, and then you'll put the hose discharge end lower down, well below the higher the fuel tank, and then you'll create a negative pressure on the hose by sucking in words. Now, if you can draw enough fuel in that, you can get that fuel line for it's gotta go up and then back down again because you've put the hose into the same place where you would normally refuel the fuel tank. So you gotta have enough pressure, enough negative pressure that you can get over the little loop that you've created. But once the fuel starts to flow downwards, he should draw in war. Fuel on this, then will allow you to empty. The entire tank on the concept is the same for much the same. For a centrifugal pump, you have to have enough negative pressure that you can continue to draw the liquid in. And if that negative pressure drops, then the liquid will no longer be drawn in and you will no longer be able to use the centrifugal pump. 32. Centrifugal Pump Operation Summary: centrifugal pump operation. Summary important information is chapter is summarised below. There are three indications Essentially, will pump is capitated noise. Fluctuating discharge pressure and flow have fluctuating pump motor. Current steps that can be taken to stop pump capitation include increased the pressure of the suction side of the pump. Reduce the temperature of the liquid being pumped. Reduce head losses in the pump. Suction piping. Reduce the flow right through the pump and reduce the speed of the pump. Impeller. Three effects of pump capitation are degraded pump performance, excessive pump vibration damage to pump impeller bearings, wear rings and also seals to avoid bump gravitation. The neck positive suction head available. MPs A. J must be greater than the net positive suction had required in psh are net positive. Suction had available is a difference between the pump suction pressure on the saturation pressure for the liquid being pumped. Gravitation is the process of the formation and subsequent collapse of vapor bubbles in a pump. Gas binding of a cent for your bump is a condition whether pump casing is filled with gases or vapors to the point where the impeller is no longer able to contact enough fluid to function correctly. Shut off head is the maximum head. It could be developed by centrifugal pump. Operating at a set speed run out is the maximum Flory. It could be developed by centrifugal pump without damaging the pump. The greater the head against, which is centrifugal pump, operates the lower the flow right through the pump. The relationship between pump flow rate and head is illustrated by the characteristic curve for the pump. Centrifugal pumps are protected from dead heading by providing recirculation from the pump discharge back to the supply source off the pump. Century pumps a protective run out by placing an orifice or fertile valve immediately downstream of the punk discharge on through proper piping system design. So that's a short summary of everything we've just learned in this section of the course concerning pump operation. We'll do a very quick with you free indications that centrifugal pump is capitated noise, fluctuates and discharge pressure and flow flood tracing Puntland's current all science of capitation. The noise. Remember the marble noise shaking marbles in a can steps that could be taken to stop pump gravitation. Remember, all of these steps relate to the fact that MPs Hey J must be kept above nps Age are so increasing the pressure on the suction, sire, reducing the temperature of the liquid being pumped, reducing the head losses. This might be, for example, by changing the piping or by using different valves. Reduce the flow rate for the pump. That's where we frost all the flow through the pump and we throw it on the discharge side. Reduce the speed of the pump impeller. And for that we can use a variable speed drive or a frequency drive. The free effects off punk gravitation are degraded pump performance, excessive pump vibration on damage to pump impeller bearings, wear rings and seals. So all of these are very bad. And that's the reason why you want to reduce capitation to zero if possible. As we said earlier, the MPs a J must be greater than then be S H R. Gravitation is process of formation and subsequent collapse of vapor bubbles. This is due to the pressure difference created by the impeller itself from the impeller royal the way through to the outer periphery of the impeller. Gas binding refers to the fact that if we have gas in this centrifugal pump we can know pump a liquid. The liquid itself is considered a working part off the pump Shut off head The maximum pressure that we can achieve it a certain operational speed again. Come back to a discharge pipe. Example. We have a long discharge pipe on the pump can pump up to a height of, say, three meters at that pump the punk and no longer pumping the higher we're not gonna have any flow. And would you see the top of the water within the pipe? And it's not gonna be moving up or down. Just could be maintained by the pressure. If we shut upon down, the war level will drop due to its own weight in the effect of gravity pump run out. This is the opposite more or less of shut off where shut off head first to pressure pump run out refers to flow and that's the maximum flow we can have through the bump without damaging it. If we increase the pressure, we're going to need to reduce the flow and if we increase the flow, then we're gonna have a corresponding drop in pressure. Dead heading is where we operate the pump with a discharge valve closed or where there's a blockage on the disguise line on this means we're gonna churn the liquid that's within the centrifugal pump. Unless we have a recirculation system from the discharge side to deception side. And you can protect centrifugal pump from run out by placing an orifice or photo valve immediately downstream of the pump discharge on through proper piping system design. So that is all of the important points for this section. We've now gone through the entire course. What I'm gonna do is to a shore wrap up in the next lesson, and then the course is finished. 33. Final Thoughts: Why me again? I really hope you enjoyed the course well done for finishing it. I think it was quite a lot of information in the course that we had to cover, ranging from theory to operation to different components. But I hope you find it'll useful. My main goal for teaching in life is that I wouldn't teach people to not just learn the theory and how to repeat stuff. Parrot fashion. That's something that always Bannon school. Quite ridiculous. If I'm honest, What I want to do is teach you to think logically on in an engineering manner, and then you'll be able to take the knowledge that you've learned, for example, in this course and apply it for out your engineering career on different machines in different industries, and you'll be able to come to logical solutions based upon your math, physics and general engineering knowledge. So that's my main goal. I really do hope now you can think through common problems that you might see in the real world and find real world solutions. Thank you very much for your time, the time that you invested in this course and once again well done for finishing I think it's quite a good thing that you've done here. You invested a lot in your career on the knowledge of game that can guarantee will be very useful hopes to you on the next course bye for now. 34. BONUS: How Multistage Centrifugal Pumps Work: in this video, we're going to look at a multistage centrifugal pump. We're going to look at some of the main components of the pump. We're gonna look at how it works. We're going to 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 we can see on this side. We've got a cross section of a multistage centrifugal. Let's go through some of the main components of the pump and some of the common terminology on the left side of the pumped through this pipe. Here, this is a suction inlet on the suction inlet, comes down and feeds into the eye off the impeller. The impeller has a wearing on the outside. It has a diffuser, this diffuser here, the diffusers stationary on the impeller rotates within the diffuser. We've got a ceiling arrangement on the left. This is a mechanical seal. The mechanical seal is used to seal the space between the pump shaft on the pub casing is prevents any leakage We've also got a ball bearing also referred to as an anti friction 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. The discharge is through the impeller out of the diffuser on. Then it passes into each impeller one after the other repeating the same process. Once he gets are finally impeller, the liquid will be discharged on. 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 not talk in more detail about how it works on what happens to the liquid as it flows through the pump, withdrawing the liquid in here on it is going down into the eye off 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 Heller's five diffusers. The liquid enters the eye of the impeller on its then front outwards, radiantly into the diffuser casing. Once it goes into the diffuser, it isn't going to 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 is going to be discharged into a space in the casing. Conceit is gonna come out on around here and then it is gonna be fed into the eye off the next impeller. We can see that we are just entering the eye of the next impeller. Here we push play, we can see the impeller turning on. It will go into the next impeller on the process repeats The liquid is thrown out. Radio Lee, It will pass through the impeller through the diffuser on again. We will get this reduction in velocity on an increase in fresh up. We repeat the process five times and finally the liquid will be discharged from the fifth Impeller on the liquid will then exit pump through this channel here and it will travel upwards. And that is a discharge pipe each impeller and diffuser are classified as one stage. Apple has five in palace and five diffusers. Therefore, it is classified as a five stage pump. It's important to realize that 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 veloute casings. Installing multiple veloute 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 frost bearing in order that the actual movement created by the impeller is 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 seals or labrum seals. Plan packing, also known as compression packing, is really used for sealing multistage pumps. There are two main type of multi stage pump designs. One is the barrel type. On the other is the ring type, the type of front we're looking at, in our example is a barrel type multistage pumps, barrel type multistage pumps that typically used for high temperature and high pressure applications. Ring Section multistage pumps are also used for high temperature, high pressure applications. Well there. There are some differences between the two designs. The barrel type pump allows for the internals of the pumps to be removed without disconnecting the outer casing on much of the associated piping. The ring section design allows for more stages to be added or removed. Although we're maintaining the pump, the external casing and piping must be removed on. This could be considerably more work compared to the barrel type punk where only the internals need to be removed and the outer casing and piping from remain in situ.