Do Pumps Create Pressure or Flow? 

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Explaining how pumps produce both pressure and flow with some fun water demonstrations.
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There’s a popular and persistent saying that pumps only create flow in a fluid, and resistance to that flow is what creates the pressure in a pipe. This video goes into some details about how two kinds of pumps work: centrifugal pumps and positive displacement pumps.

Practical Engineering is a USlift channel about infrastructure and the human-made world around us. Hosted, written, and produced by Grady Hillhouse. We have new videos posted regularly, so please subscribe for updates. If you enjoyed the video, hit that ‘like’ button, give us a comment, or watch another of our videos!

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This is not engineering advice. Everything here is for informational and entertainment purposes only. Contact an engineer licensed to practice in your area if you need professional advice or services. All non-licensed clips used for fair use commentary, criticism, and educational purposes.

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Source: www.youtube.com/watch?v=U6fBP...
Producer/Host: Grady Hillhouse
Assistant Producer: Wesley Crump

Published on


May 4, 2021




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Practical Engineering
💧 Give me your best pump mantras. I'll meditate on the best one. 📺 Don't forget to jump on this great Nebula/CuriosityStream deal. curiositystream.com/practicalengineering
Deeksha Rathour
Please make more videos on different types of pumps
It won't work without water.
electric 11 days ago
The amount of flow a pump creates is based of the conditions in which it is placed
Blake Lonsdale-Cook
Primed pumps promptly provide persistent pressure, persistent pressure permitted to propagate provides pouring particles.
Nathan keller
Nathan keller 14 days ago
Pumps create flow that becomes pressure
Kevin A.
Kevin A. 5 hours ago
What is crazy for many to see is that if you put a pressure gauge between the pump outlet and gate valve, as you close the gate valve the pressure goes up. Okay, that is normal but look at the amp meter! It goes down! It's because the work the pump is doing is moving water, but when you stop the flow, you're also stopping the work. The pump impeller is just free-spinning without a load. I've won many bets on that one! The normal thinking is that if the pressure goes up so does the amps. Just like the fans, take their work away, you take their load away.
More Cowbell
More Cowbell 6 hours ago
As soon as i saw the VSD, i knew this was going to be good =)
Misael Moreno Luna
I enjoy watching your videos, I find them very informative! I came here to watch the video, and in the process, I just signed up for a year of Curiosity Stream😂😌🙂🧐
Kyle Alexander
Kyle Alexander 2 days ago
I wanna know how the pumps change when theyre pumping into a 95% full 495k gallon tank. Specifically 25 hp pumps.
Kyle Alexander
Kyle Alexander 2 days ago
As someone who has moved a pretty large volume of wine and juice for wine i can tell u this is all true. If u suck air u lose pressure
Michael Verde
Michael Verde 3 days ago
Booster pump systems will run and then shut off based off of pressure readings. When the pumps shut off, no ones using water and all components are working right, the pressure will remain in the system. Pumps made that pressure baby
KeijoAmbersson 3 days ago
If we go to machinery hydraulic systems, we start to get variable displacement pumps that actually do determine how much flow they provide at any given time. But the displacement of them in given moment is usually controlled by the system pressure. Certain pressure threshold is reached, and pump displacement is lowered to lower the flow, and in turn lower the pressure. The pump is controlling itself, within the system parameters. I sometimes scratch my head and wonder what kind of person originally came up with this. It's brilliant and kind of silly at the same time.
More videos about pumps.
Austin Schwebel
Austin Schwebel 5 days ago
I'm upset you didn't bring up the huge change in pump flow if you change RPM from 2/4/6 pole and along with impeller trim relative to the pump curve.
Dallas Arnold
Dallas Arnold 8 days ago
I have to argue the point. How much pressure is there at the point of discharge from the pump ? Well you can not measure that without creating some type of restriction or resistance which is actually where the pressure is created. If the fluid discharges into a pipe it is already incurring a restriction.
Park Nelson
Park Nelson 8 days ago
You just summed up ME 460 in 10 minutes.
Mr. Kips
Mr. Kips 10 days ago
As an electrician, I laugh when someone says “ It’s not the voltage that kills you, it’s the current”. ElectroBOOM has also covered this subject.
sandesh honmane
sandesh honmane 11 days ago
If the motor RPM can be varied then positive displacement pumps can also deliver variable flow.
Al To
Al To 12 days ago
Creo que la tecnología de los taladros de aire podría mejorar las motocicletas pues desde ser mejores y más fuertes explosiones a usar hidrógeno en explosiones de combustible, sino el principio de motores de aire por compresión y no contaminantes, junto de eléctrico a aire comprimido o de esa tecnología a ser en vez de taladro para concreto también en motocicletas y transferencias de energía, eléctrica a neumática o usar como cámaras que soporten hidrógeno de combustible, según quieran opciones de tecnología sugerencia.
Al To
Al To 12 days ago
Las cadenas de transición que usan bicicletas y motocicletas, creo que se puede mejorar, con diseño de ciertos animales vertebrados como representar en una cadena de metal y engranes, la tecnología de hecho de engranajes imposibles aplicada a cadenas de transición que permita poco desgaste y fricción en cadenas que parecen engranajes alien, pues casi no fricción an dientes sino empujan como los videos de engranajes de cubos de rugbik con engranes, engranes no convencionales y hasta de formas de óvalos y no círculos para ser más dientes del engranaje y empujar más que friccionar y desgastar en circular, incluso las orugas de tanques servirían en parte en cadenas de transmición, también la tecnología de rotulas de caderas o huesos por forma de sus uniones en serie asemejando dientes de engranajes, sugerencia.
John Morgan
John Morgan 12 days ago
Ok, the experiment at 2:52 is such a wonderous experimental demonstration to be able to find with ease. Bless your heart. Now, what happens when the experiment is done using different gauges of tubing? Or just someone tell me what would happen?
Renegade50deuce 13 days ago
Pumps create neither pressure or flow, they provide energy. Pressure and flow being a consequence of that energy.
bassamatic 13 days ago
the pump creates a pressure DIFFERENTIAL, creating flow from high pressure to low pressure.
Alexander Wlad
Alexander Wlad 13 days ago
If this video reaches 40k likes Grady will shoot a video on him doing 100 chest pumps
Tonic Artos
Tonic Artos 13 days ago
If you want to remove the pressure from the equation, don't you to separate it into positive flow and negative flow? As in, you have a degree of slip (negative flow) in the centrifugal pump dependent on the potential in the body of water in the output.
Amit Borkar
Amit Borkar 13 days ago
Make demonstration of multiple pump how effective it is.. Will increase flow or head with same head pump if placed in parallel or series
Sagan The Khajiit
Sagan The Khajiit 13 days ago
"It's not the voltage that kills you, it's the current" kinda sounds like "it's not falling that kills you, it's hitting the ground"
Ticked Off Sheikh
Ticked Off Sheikh 13 days ago
Great video. I love the subject myself. Can you do a comparison between centrifugal pumps vs Archimedean screw type pumps? I have seen a drainage centrifugal pump with a bore of 60 inches delivering 600 tons per minute. Which is more efficient for drainage applications? Thank you in advance.
Blake Lonsdale-Cook
Primed pumps promptly provide persistent pressure, persistent pressure permitted to propagate provides pouring particles. If you're willing to give up the alliteration at the end, then instead use: Primed pumps promptly provide persistent pressure, persistent pressure permitted to propagate provides flow.
RenchesAndSords 14 days ago
por que no los dos
BaronZ 14 days ago
As an electical engineer this rings a lot of bells. The behavior of diodes/transistors and motors can be characterized through intersecting functions of intrinsic and extrinsic behavior of the system in response to a change in voltage/current.
Riku Lappi
Riku Lappi 14 days ago
Please more videoes on pumps! Pleeeeeees! Here in Finland most folks own a fraction of a family summer cottage by a lake or have access to one through friends or access is a fringe benefit provided by your employer. Practically every cottage with electricity has a fixed water pump, often submersible ones for winter when the primary pump and pipes are empty and dryed, consequently inoperable. (I recall people in Texas had pumps and pipes destroyed by freezing water recently😭). The video was great. I will pass it on to my kids. Cars have multiple pumps, aquariums have pumps, an air compressor is a pump. Pumps are cool. However, elementary understanding may save you a lot of money...
meowmeowbobo 14 days ago
Erm so basically impeller pump obey ohm's law? The flow is depended on the pressure (pump characteristics) and reaistance(pipes)
dragonatorul 14 days ago
"This isn't rocket science". I'm not a rocket surgeon, but I'm pretty sure pumps and fluid dynamics are a big part of at least designing rocket engines and fuel tanks.
Stefs Engineering
Stefs Engineering 14 days ago
0:30 it isn't rocket science, but a large part of it for sure. Take for example the new SpaceX booster that has to distribute fuel and oxidizer to 29+ engines at quite a significant rate.
warren osborne
warren osborne 14 days ago
Thank you for your very clear and concise explanation of physical properties without going over the heads of the majority of viewers. I don't think that it would be detrimental to slip in just a bit of math. (gently)
Sylvia Duke
Sylvia Duke 14 days ago
May father was a steam engineer during WWII and worked for Memphis, TN Light, Gas & Water over 25 years. I got to see him check the plumps every few minutes and walk the plant! He was very careful about this job. He tried to explain it but I was only 7 at the time.
chris thorney
chris thorney 14 days ago
would a positive displacement pump not slow down as it reaches higher head heights, because it would slow down until the motor driving it stalls out and cant pump against so much head pressure, so thus its flow rate would decrease as head height increases because its pumping against a higher backpressure
Practical Engineering
Depends on the motor and drive. Many pumps use synchronous motors that can’t slow down
thokim84 14 days ago
Pumps suck.
MrBabyBitch666 15 days ago
It is absolutely the voltage that kills you
Blake Lonsdale-Cook
No, it isn't. It's the wattage that kills you. Wattage is a function of amperage and voltage in accordance with Ohm's Law.
Earl Lighthill
Earl Lighthill 16 days ago
Where were your safety glasses for this demonstration?
G0sentrick 16 days ago
"Tide goes in, tide goes out. You can't explain that." - Bill O'Reilly
Kent Freeman
Kent Freeman 17 days ago
One way to look at this is if the pump is turned off is there any system pressure?
Ames Doe
Ames Doe 18 days ago
thanks for the graphs about the different curves! i also appreciate the video editing. you're a wonderful resource, Grady.
Steve Clayton
Steve Clayton 19 days ago
how about a show on PD pumps? blackmer and corken pumping a pressurized gas like propane and or NH3
mbc1994 20 days ago
Could you make a video of Water Pressure Regulator Valves, and espceially how they work, in detail.
DJ Deckard Cain
DJ Deckard Cain 20 days ago
Grady! Have you thought about doing a video about the Gigapress that Tesla had Idra build for them? That thing's a modern engineering marvel! 430,000 kilonewtons of force!!!!!! That's over 1,300,000 lbs of force!
Blake Lonsdale-Cook
I'm very curious as to what it's used for now.
A B 20 days ago
A. What is the best water pump design & motor to use to do the following: 1. Pump water from a lower elevation to a higher elevation using a battery operated pump (e.g. ~7 ft H via .5" ID tubing) 2. Maintain the proper water flow rate based on the user's adjustment of H & C water faucets (e.g. .5 gpm to 3.5 gpm) 3. Minimize battery energy usage at various user defined water flow rates B. What type & size pump would be ideal for such an application? C. Would a one-way check valve reduce energy usage or is that unnecessary? D. Is a variable speed pump ideal or would a less expensive fix speed pump be a better choice? E. What would be be an ideal pump (brand & model) for such an application?
It Has Been Written
I’ve had a lot of friends who are engineers, i myself am a mechanic, and I always smile when i see Grady puts little eyeballs on the action pieces knowing full well how special it is for an engineer to humanize things for the rest of us emotional non-Vulcans. It’s a special breed who can bridge that gap. 🖖🏽 And amazing how much of a difference they make! 👀
cesar ortiz
cesar ortiz 20 days ago
The cooperative mouth densply trouble because meeting spectacularly happen excluding a embarrassed chick. racial, lying loss
BlueParadise 21 day ago
I have enjoyed your channel, would you do a video on lifting water. Pulling water up via suction vs pushing water via pressure. single stage lift, vs multi stage lift. 1" pipe vs 4" pipe. Love to see it. Thanks
Grass Geese
Grass Geese 21 day ago
Wow, the comparison to voltage/current was actually very helpful for me!!! I'm learning about electricity at the library lately, and i am shocked (lol) at how similar flow of electrons and flow of water can appear
seasong 21 day ago
I hate it when I accidentally choose the wrong pump for my city's water supply 😭
Love the opening statement do pumps create pressure or flow? immediately remind me of the engineering school saying that wings lift a plane creating vacuum that sucks the plane upwards!! then the argument with the other guys saying that its actually higher pressure on the bottom of the wings!! and as you mentioned with current & voltage.. you can't have one without the other....
gaurav rade
gaurav rade 21 day ago
William 21 day ago
Shortened motto, "It depends..."
Hans Ulrich Johner
The Bernoulli equation describes the relation between pressure and flow nicely!
Duncan Harris
Duncan Harris 21 day ago
Nick Lewis
Nick Lewis 22 days ago
Awesome video! I am a project engineer for a large diameter(54” into 92”) sewer project where we bypass 30MGD. I just went through learning all this and this video does a great job simplifying a complicated topic.
Maggie Jetson
Maggie Jetson 22 days ago
They are the same thing, pV=nRT.
John Abraham Gargantiel
i think your float is installed upside down: your flowmeter
roger brandt
roger brandt 22 days ago
Can’t believe there’s only 2 million likes, guess the people nowadays don’t care about learning.
Andy 22 days ago
Without watching the video, the answer is simple: Pumps create pressure which causes flow once resistance (friction, gravity, etc) is overcome.
Friday Californiaa
Friday Californiaa 23 days ago
You have to create a video about water cooling in computers. I feel like there are many mistakes made in this domain about pumps =)
Sander Zewald
Sander Zewald 23 days ago
It's not the voltage or current that kills you, it's the Wattage.
stampy Dragon
stampy Dragon 23 days ago
I’d make a pump from one way valves using flow from a river to create the operation
LLiC 23 days ago
Put it in Spanish too, please
Aaron Klein
Aaron Klein 23 days ago
Just saying Grady I think we enjoy just about anything you think might be interesting. Loved this one.
rupe53 23 days ago
To make it simple, pumps create pressure differential. It's the difference between inlet and outlet that causes the fluid to flow. What most don't bother to figure is the plumbing (both distance and size) plus change in head pressure / height also figures into this pressure differential. Longer pipes and smaller pipes have more resistance to flow. Change in height of the inlet or outlet can also change resist or increase flow rates. Bottom line is it's not all about the pump itself. The entire system design is part of the pump's capacity.
pmailkeey 24 days ago
Grady, feel free to answer this one in a video: Why do people with hydraulic drives refer to them as hydrostatic systems when clearly fluid motion is dynamic.
pmailkeey 24 days ago
CLEARLY :) 0:09 pumps create pressure. The pressure they create CAN create flow. Next question ? Perhaps one a bit harder ?
Broc Luno
Broc Luno 24 days ago
Would very much appreciate an examination of a Berkeley Jet Pump in a boat. Near zero head, lots of volume, rising pressure curve against a fixed nozzle based on RPM. How to extract maximum boat efficiency? More discharge velocity? More discharge volume? Let's say target RPM is 5,000 - available HP at that RPM is 450, boat is planing hull at anything above 20 mph ... Berkeley Jet Pumps are considered mixed flow pumps, not entirely radial, not entirely axial ... Any ideas ??
Dragon Curve Enthusiast
Great video as always! Thanks Grady! :-)
Stephen Stromsness
Stephen Stromsness 24 days ago
First video of yours I've watched very informative and well done. Really appreciate it.
Fun Day Sailing
Fun Day Sailing 24 days ago
At 6:30 you added resistance to the system by the way of head. The weight of the water sitting in the head tube was the resistance to flow. Enough so that the pump was unable to overcome the resistance to flow. I get your point that pumps and restrictions are closely related and you need a pump that can overcome the resistance in a given system but the pump is not the source of pressure, especially not in this example - it created flow right up to the point to when it was used beyond its capacity and stalled out, unable to create any more flow against the pressure build up.. You can only have pressure within a container. The pressure in the system was the weight of water contained within the head tube. In this example the pressure and head height are directly related because the pressure is the result of gravity pulling the water back into the container (or pipe).. More head = more pressure and no head = no pressure. If you exchange the pump for a closed valve in this example there is still the same pressure in the system, thus the pump is not creating any pressure. I stand by the saying that pumps create flow not pressure, but I think it would be more accurate to say that pumps impart kinetic energy into a system and it is the resistance within that system that converts the kinetic energy (flow) into potential energy (pressure). For you electricians........A generator (pump) doesn't create light, it creates electricity - it is the light bulb (resistance) that converts the electricity into light. Thoughts?
Greta Thunderer
Greta Thunderer 24 days ago
Positive displacement pumps don't always have a linear characteristic curve. I work in the healthcare industry and we use positive displacement pumps for our detergents for surgical instrument reprocessing. After installation they must be calibrated because the head and pipe length both have direct impacts on how much detergent is pumped per revolution.
Raymond J
Raymond J 24 days ago
Dead Skin Rippers
Dead Skin Rippers 24 days ago
By virtue of pressure drop created by the pump rotor blades flow is produced. It's like understanding how u suck water from a straw. Unless there is a pressure difference between atmosphere and suction from ur mouth no flow will take place.
J-max FromOR
J-max FromOR 24 days ago
Thanks Grady for interesting video. In summary, sounds like all pumps create pressure, and how much flow, if any and which direction, depends on the input and output systems of pressures, energy losses in pipe friction, valves, and corners, and in other pumps, turbines, etc.
Robert Kesselring
Robert Kesselring 25 days ago
CAD Thunkin
CAD Thunkin 25 days ago
As a lift station designer, I know the big fail is when the pump is lifting very little, and the pump spins away. (called flooded suction) The power consumption is highest when it spins the fastest. You have to be careful the electrical system can handle that, or it trips and you can't do what seems the simplest thing, lifting water no elevation. So it needs more power when making more flow. Therefore, its a flow machine :)
Ron Masters
Ron Masters 25 days ago
Had a long, confused discussion over lunch one day with a friend who needed to pump water into a very high reservoir, and was trying to arrange multiple pumps. This clarifies the whole problem.
Robin Blom
Robin Blom 25 days ago
Love your vids, keep up the awesome work!
Jim Holmes
Jim Holmes 25 days ago
How come the 300,000 volt spark that jumped from the Van de Graff generator didn't kill me?
MalcolmCooks 25 days ago
"It's not the force of the gun that kills you, it's the speed of the bullets!"
44R0Ndin 12 days ago
More correctly, "It's the momentum of the bullet over the short time period of the interaction that delivers a lot of damage to your body". Bullet proof vests allow the interaction between bullet and flesh to happen over a longer period of time without causing permanent damage to the flesh, and ceramic body armor plates allow the bullet to break them in a controlled manner to dissipate the kinetic energy in the incoming projectile entirely before it reaches the flesh.
Jomelle Samuel
Jomelle Samuel 25 days ago
Do more pump vids
Jasper Frith
Jasper Frith 25 days ago
As a Civil Engineering student trying to get through my hydraulics modules, please come lecture us, our current lecturer is just obsessed with is postgrad students :/
Rohan Grant-Dawes
Rohan Grant-Dawes 26 days ago
Brilliantly explained. Always love your videos. Left feeling very satisfied. Amazing work
LegitGopnik 26 days ago
Teachers use water flow as an analogy to teach electricity easier. I don't see anything easier about water.
Nine Horse Hitch
Nine Horse Hitch 26 days ago
. . . To be nit picky and technically correct, shouldn't the focus be on how the pump applies a force on the fluid? Centrifugal pump applies a force on to the water by accelerating it outwards from the center of the pump this created a suction on the water in the suction. For a centrifugal it created the flow first. Positive Displacement pump draws the fluid in. It is creating a pressure to suck the fluid in.
I used to sell Industrial pumps and tanks and ironically we didn't delve much into centrifugal pumps. Positive displacement pumps (namely Viking internal & external gear pumps were our bread and butter) but I'm glad because it's much easier to do one or the other, dealing with both can be quite the headache!
Steve aaron Defries
ummm this vid would be used in rocket science... you know fuel pumps and such
Who Ever
Who Ever 26 days ago
If people really wanted to know the answer to this question, then your answer is the best one. Leave the simplistic answers to those who want to talk about it without actually thinking about it.
João Pedro Reis
João Pedro Reis 26 days ago
Maybe something like this: Pumps transfer energy to the fluid. Kinetic or potential, depending on the context.
SqurtieMan 26 days ago
Here's my catchphrase: "Do pumps create pressure or flow?" "Yes"
J-max FromOR
J-max FromOR 24 days ago
Should have said “input and output systems.”
J-max FromOR
J-max FromOR 24 days ago
My understanding is all pumps create pressure, and how much flow, if any, depends on the discharge system.
Kamasuk W
Kamasuk W 26 days ago
How I live my life 8:24
Michael Rinkle
Michael Rinkle 27 days ago
I work with centrifugal pumps every day! 1 each for each of the 3 Grand Nationals and 2 each for the 86 S-10 Blazer 4x4 5.7L(twin turbo), and 95 C1500 4.3L (twin turbo) :D
Austin M
Austin M 27 days ago
This was one of the nerdiest instances of throwing shade I’ve ever seen
gumelini1 27 days ago
Pumps create flow, pressure is resistance to flow
Angel Valdovinos
Angel Valdovinos 27 days ago
Flow is pressure 🤡🤡🤡
Tech_ 49FPV
Tech_ 49FPV 27 days ago
Oh the videos I watch at 0300 lol.
Tips 4 truckers
Tips 4 truckers 27 days ago
Grady im so impressed with your aray of knowledge
James Robins
James Robins 27 days ago
Hi Grady, How about getting us an inside view of the fountains at Longwood Gardens. It was built by Pierre du Pont in SE Pennsylvania. It is an incredible display.
Tom Jerry
Tom Jerry 28 days ago
I almost wish I haden't liked this video because when I saw those augmented graphs at 3:40 my jaw dropped at how well done those were.
starflowers 28 days ago
I have never seen you so happy
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