Pump Chart Basics Explained - Pump curve HVACR
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Date: 2023-11-17
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Comments and reviews: 30
Brendan
Is there a theoretical derivation for the shape of a pump curve?
I guessed maybe a centrifugal pump imparts constant energy per unit mass to whatever fluid passes through it. Then you'd get E = constant (for any given fluid density) = P + (1/2)dv2 (d is density, or h = E/(dg) - Q2/(2gA2. This has the shape of an upside down parabola (right basic shape, but when I try to compare it to real pump curves, the real curves turn downwards something on the order of 100 times faster than my theoretical model. Do you know why this might be? Am I making some unit conversion error, or is the whole thought process just wrong?
If the real pump curves turned down something like 10-50% faster than the theoretical one, I'd be happy, because I guess the pump doesn't conserve energy perfectly and it doesn't have the same efficiency at all operating ranges. But getting a result 10, 000% different than the theory is unsatisfying.
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Is there a theoretical derivation for the shape of a pump curve?
I guessed maybe a centrifugal pump imparts constant energy per unit mass to whatever fluid passes through it. Then you'd get E = constant (for any given fluid density) = P + (1/2)dv2 (d is density, or h = E/(dg) - Q2/(2gA2. This has the shape of an upside down parabola (right basic shape, but when I try to compare it to real pump curves, the real curves turn downwards something on the order of 100 times faster than my theoretical model. Do you know why this might be? Am I making some unit conversion error, or is the whole thought process just wrong?
If the real pump curves turned down something like 10-50% faster than the theoretical one, I'd be happy, because I guess the pump doesn't conserve energy perfectly and it doesn't have the same efficiency at all operating ranges. But getting a result 10, 000% different than the theory is unsatisfying.
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bajatoma
Explanation of flow rate vs head is somewhat lacking. The sentence say, if we want 6GPM, then on setting 1 we will get around 4. 2ft of head
Here is the thing - just because we wanted 6GPM, doesn't mean I'm going to get it. As far as I understand, it's other way around! IF you have 4. 2ft of head, the pump on speed 1 will be able to produce 6GPM. That's why I find this chart super confusing, because I'm just used to have on X input, and on Y axis outcome.
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Explanation of flow rate vs head is somewhat lacking. The sentence say, if we want 6GPM, then on setting 1 we will get around 4. 2ft of head
Here is the thing - just because we wanted 6GPM, doesn't mean I'm going to get it. As far as I understand, it's other way around! IF you have 4. 2ft of head, the pump on speed 1 will be able to produce 6GPM. That's why I find this chart super confusing, because I'm just used to have on X input, and on Y axis outcome.
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Omar
Amazing Video! Thanks guys you're doing amazing job. The way you explained it is very clear and easy to understand.
But I have to disagree with an info you mentioned at 1: 00, as I know pumps don't produce pressure, they produce flow only and the pressure forms from load and friction and the pump has to overcome it to deliver the desired flow.
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Amazing Video! Thanks guys you're doing amazing job. The way you explained it is very clear and easy to understand.
But I have to disagree with an info you mentioned at 1: 00, as I know pumps don't produce pressure, they produce flow only and the pressure forms from load and friction and the pump has to overcome it to deliver the desired flow.
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JoeySmig_Beats
How is it that if your NPSH is increased by a positive water supply that your pump discharge is also increased? I would have just assumed that since my impeller is rotating at a certain speed set by the motor that my pump discharge would have remained the same. Can anyone please explain for me?
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How is it that if your NPSH is increased by a positive water supply that your pump discharge is also increased? I would have just assumed that since my impeller is rotating at a certain speed set by the motor that my pump discharge would have remained the same. Can anyone please explain for me?
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shyam
I am predicting breakdowns in a water pump for my project I have taken the dataset from the kaggle website and I would not able to find out the parameters of the pump he used and what type of sensors he used for water pump. Could you please answer by questions. That will be helpful for my project.
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I am predicting breakdowns in a water pump for my project I have taken the dataset from the kaggle website and I would not able to find out the parameters of the pump he used and what type of sensors he used for water pump. Could you please answer by questions. That will be helpful for my project.
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Take
very clear, precise and informative. Do you have any info on mud pumps and their basic operating procedures would be most helpful if any info and if I applied to join the engineering mindset would i get the calculator sheets as excel provided and they covered under the membership fee? Thanks again
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very clear, precise and informative. Do you have any info on mud pumps and their basic operating procedures would be most helpful if any info and if I applied to join the engineering mindset would i get the calculator sheets as excel provided and they covered under the membership fee? Thanks again
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education
I have a question,
If a centrifugal pump flow limit is from 60 LPM to 535 LPM at 3500 rpm, does the low flow limit of 60 LPM changes with running the pump at lower rpm? Does this limit changes goes down when we run the pump at lower rpm?
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I have a question,
If a centrifugal pump flow limit is from 60 LPM to 535 LPM at 3500 rpm, does the low flow limit of 60 LPM changes with running the pump at lower rpm? Does this limit changes goes down when we run the pump at lower rpm?
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edfx
3: 50 I cannot see how Head value in meters apply here. Pump raises water, but the same water returns due the gravity, therefore head is always zero. How do you figure out head value in meters in closed system like here?
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3: 50 I cannot see how Head value in meters apply here. Pump raises water, but the same water returns due the gravity, therefore head is always zero. How do you figure out head value in meters in closed system like here?
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Mauricio
9: 18
you mention that the same pump would be able to perform at the maximum efficiency just by changing the flowrate/operating head. I'm assuming you meant same pump with different impeller size.
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9: 18
you mention that the same pump would be able to perform at the maximum efficiency just by changing the flowrate/operating head. I'm assuming you meant same pump with different impeller size.
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partyboy
Hey Paul I want to do more for you than simply buy you coffee; I am looking for a pump that can use for seawater desalination plant. A pump that can pump-out high pressure steam. can you help? :)
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Hey Paul I want to do more for you than simply buy you coffee; I am looking for a pump that can use for seawater desalination plant. A pump that can pump-out high pressure steam. can you help? :)
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Klint
Just a heads up in the animation showing the VFD the amplitude is changing when it should be the frequency. Basically the peaks should be getting closer to each other instead of closer to 0.
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Just a heads up in the animation showing the VFD the amplitude is changing when it should be the frequency. Basically the peaks should be getting closer to each other instead of closer to 0.
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al
pump head can also be measured in blondes and those using the metric system
it be measured in brunettes
so after a hard week one individual could have a head pressure of 2 blondes, ,
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pump head can also be measured in blondes and those using the metric system
it be measured in brunettes
so after a hard week one individual could have a head pressure of 2 blondes, ,
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Mirage
Can you clarify, the graphic at 4: 46 seems wrong or inverted? At max head, there will be minimum flow rate so the height of the water coming out of the pump should be at its max
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Can you clarify, the graphic at 4: 46 seems wrong or inverted? At max head, there will be minimum flow rate so the height of the water coming out of the pump should be at its max
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Jack
Thank youIm civil engineer and Im currently working water industry, I do lot of mechanical works, big pumps water treatment plantthis information very helpful to me. cheers
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Thank youIm civil engineer and Im currently working water industry, I do lot of mechanical works, big pumps water treatment plantthis information very helpful to me. cheers
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Jose
Energy goes where?
at 01: 25 there is no flow, yet the pump is stuggling it's maximum; where does the energy go to? just to heat up the water column?
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Energy goes where?
at 01: 25 there is no flow, yet the pump is stuggling it's maximum; where does the energy go to? just to heat up the water column?
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ZK
I would give you thousands of likes if I could. You literally explained the bloody thing soo much better than the walls of text in my lecture notes
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I would give you thousands of likes if I could. You literally explained the bloody thing soo much better than the walls of text in my lecture notes
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Vijil
Thanks for this interesting video. I have got one question. Can reducing the size of impeller and casing together maintain the pump efficiency?
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Thanks for this interesting video. I have got one question. Can reducing the size of impeller and casing together maintain the pump efficiency?
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Ahmed
Dear sir. I have amixed flow pump when i decrase the flow and pressure increase the power also (increase) what is the problem about this
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Dear sir. I have amixed flow pump when i decrase the flow and pressure increase the power also (increase) what is the problem about this
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CH
How can we calculate the flow rate of a split type centrifugal pump if we know the refrigerant flow rate through the chiller's evaporator?
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How can we calculate the flow rate of a split type centrifugal pump if we know the refrigerant flow rate through the chiller's evaporator?
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Durzo
11: 28 Australia and New Zealand also operate with the same Voltage and Hertz as European Union, however it's 240V / 415V typically.
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11: 28 Australia and New Zealand also operate with the same Voltage and Hertz as European Union, however it's 240V / 415V typically.
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dheya
Who & how to fill the gab in designing a system of fluid ( other than water ) & the pump curve out of water test by manufacturer?
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Who & how to fill the gab in designing a system of fluid ( other than water ) & the pump curve out of water test by manufacturer?
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engineering_mindset
As a complete novice to the subject matter this was the absolute perfect video. AND I CAN FOLLOW THE EXPLANATION!
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As a complete novice to the subject matter this was the absolute perfect video. AND I CAN FOLLOW THE EXPLANATION!
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Koh
1: 10 is mind blowing. As a fire sprinkler contractor i learned a new concept about understanding the concepts behind pump curve.
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1: 10 is mind blowing. As a fire sprinkler contractor i learned a new concept about understanding the concepts behind pump curve.
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Dr.
Thanks Paul. I did this course in my Electrical Engineering program and I am just understanding Pump Curve. great job.
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Thanks Paul. I did this course in my Electrical Engineering program and I am just understanding Pump Curve. great job.
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Brien
why would you want to machine down the size of the impeller? why wouldnt you just run with more power than you need?
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why would you want to machine down the size of the impeller? why wouldnt you just run with more power than you need?
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Riskan
Really great! This short video covers almost all the pump curve concepts I needed for my exams. Thank you so much.
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Really great! This short video covers almost all the pump curve concepts I needed for my exams. Thank you so much.
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Anil
I really love your video, i request to you that please upload video about mechanical seal design and selection
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I really love your video, i request to you that please upload video about mechanical seal design and selection
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Slengo
Is NPSH calc applicable for closed loop systems? I only saw open loop examples and nothing for closed system
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Is NPSH calc applicable for closed loop systems? I only saw open loop examples and nothing for closed system
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Gabe
Get a mechanical engineering degree and hit me up after you take fluid mechanics if this interests you.
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Get a mechanical engineering degree and hit me up after you take fluid mechanics if this interests you.
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Tomi
friction? i would have said gravity. and lil bit friction. generally pipes have nice smooth walls.
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friction? i would have said gravity. and lil bit friction. generally pipes have nice smooth walls.
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