Do Pumps Create Pressure or Flow?

04 Th05, 2021
425 181 lượt xem

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 VIworld 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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Producer/Host: Grady Hillhouse
Assistant Producer: Wesley Crump

  • 💧 Give me your best pump mantras. I'll meditate on the best one. 📺 Don't forget to jump on this great Nebula/CuriosityStream deal.

    Practical EngineeringPractical Engineering4 ngày trước
    • Pumps do work. Pressure is potential energy. Flow is the realization of time and work, realizing the potential energy.

      WillWillNgày trước
    • @Ian B LoL 😆

      Ross TempleRoss TempleNgày trước
    • Water invented humans so it could flow uphill.

      Ian BIan BNgày trước
    • Pumps do, in fact, go brrrr.

      MaxSeidel1MaxSeidel12 ngày trước
    • This makes me wonder why sewer systems in some cities don’t recapture energy from septic system in forms of water wheels. Could you do one on ram pumps. And how do water bladders increase water pressure. That one always stumps me.

      Ross TempleRoss Temple2 ngày trước
  • Where was this video when I took my Fluid Mechanics class last semester!

    stststststst4 giờ trước
  • My wife mentioned that she would be using VFDs for those applications (in regards to changing system curves). Is there a reason you wouldn't use these in an application like city water treatment?

    Tyler ThrailkillTyler Thrailkill4 giờ trước
  • All pumps create a negative pressure vacuum at some point along the supply side of the pump.

    Videos From ElsewhereVideos From Elsewhere4 giờ trước
  • pump it ah ah AAAAAAAAAAAH

    01000100010001005 giờ trước
  • Can anyone tell me what the reasoning is to have (at 1:49) the pump inlet/discharge diameter is smaller than the inlet/discharge piping diameter? i.e. why is there a reducer on the inlet and expander on the outlet? Thanks

    getrektdm8getrektdm85 giờ trước
  • Keep up the good work! I can only hope you make an impression on the people that don’t understand!

    Mike FasanMike Fasan6 giờ trước
  • I would like you to explain the differences in the centrifugal liquid pump and the centrifugal supercharger? The centrifugal supercharger or turbo charger actually compress the air through the discharge tube, whereas the roots positive displacement pump just move the air from the inlet side to the outlet side, which should also be correct for the rotary vane pump with some minor built in pressure with the vane pump - now modern air compressors use the screw pump to compress the air for the pneumatic devices that we use. Then there is the axial flow pump used in jet engines, which is very similar to the scroll in the impellor of the centrifugal pump --- However I can say that your "Head" pressure can cause the centrifugal pump to generate less pressure and the same flow -

    Wizards HomeWizards Home8 giờ trước
  • "voltage and current go hand in hand" no, not really... or not necessarily in the context of what kills you. Voltage is a potential energy difference caused by an electric field, or by resistance/loss of energy. Current is the flow of charge. you can have current (flow of electrons) with no voltage if there's no resistance (in a superconductor). You can also have high voltage without high current. When your body gets charged up with static electricity, you'll develop a voltage of up to 25 thousand volts (yes, 25K). When you touch something conductive, you'll get a sudden zap as the static electricity is discharged, but that won't kill you because it's not enough current.

    TudorTudor9 giờ trước
  • I'm not trying to argue, but in your demonstration of the aquarium pump maxing out at the max head I agree that in that demo it is creating pressure. But even though the tube is unrestricted wouldn't the max head be kind of considered almost resistance to flow therefore the pump can now create pressure? My expertise is in composites engineering and I'm trying to learn more about pumps. I loved this video by the way!

    Dave PeralaDave Perala9 giờ trước
  • why is the pipe size reduced on the inlet/outlet from a pump ? i do understand that it is to get higher flow through the pump but why ?

    VatneholVatnehol9 giờ trước
  • I would have guessed that pumps created pressure. Here's why. I've used an air compressor a few times, and I can see the pressure guage on the tank go up without any flow coming through the house. Also, my home tap pipes have strong pressure, without any of the taps being open. Please do an episode on how air compressor tanks build pressure without flow, and maybe also similar vacuum chambers. Thanks.

    electricketchupelectricketchup10 giờ trước
  • That's backwards. Pressure is what creates the flow

    mowgli2071mowgli207110 giờ trước
  • Both. They create both. Put your thumb over the end of the pipe and tell me different.

    Joby FluorineJoby Fluorine11 giờ trước
  • It depends on the pump. A reciprocal pump creates a virtually constant flow (and the pressure can achieve quite high levels if the out flow is blocked), while a centrifugal pump creates constant pressure.

    Samuel LourençoSamuel Lourenço12 giờ trước
  • Always interesting videos, many greetings from Portugal

    Luis MotocasLuis Motocas12 giờ trước
  • Who will win the 2 000 000 subs? You or Cody's Lab? I have a feeling you will both get it pretty soon.

    Alexandre ValiquetteAlexandre Valiquette13 giờ trước
  • I'm an engineer who has designed centrifugal and peristaltic pumps. This video was awesome.

    C ShieldsC Shields13 giờ trước
  • might you do a video about water cooling pumps? there's so much confusing information and just so few factual data -.-

    Mirko1891Mirko189114 giờ trước
  • That about axial piston pump&?

    Ivan IvanIvan Ivan14 giờ trước
  • )

    Ivan IvanIvan Ivan14 giờ trước
  • I'm subscribed but I just got to say if you had a channel just about pumps, I'd subscribe to that too.

    ChadChad15 giờ trước
  • Oh we care what's happening inside when cavation eats up impellers and turning vanes.

    Sean SignerSean Signer15 giờ trước
  • give this man a beer, you are right it is the voltage and the current even the resistance goes hand with hand in the electric schems also good video

    ulises alvarezulises alvarez15 giờ trước
  • Pumps create flow...pressure is a by-product of its limitations or restrictions. This is why you select a pump based on the required flow based on those limitations and restrictions. It often requires more energy and different impeller designs to achieve this. Let's use multi stage pumps to demonstrate this. A multi stage pump is designed to still give the desired flow at high restriction. I have never in all my years of industry experience encountered a pump system that was not designed around moving a desired volume of liquid and thus designed to take into consideration the influences affecting the desired flow in selecting a pump. Let's use a simple example... I customer approaches a business looking for pump for their well. The request would be something like; I have a well that is 30 feet deep and need to pump water up the hill to a tank that is at the end of a 500 foot 2" pipe but at an elevation of 300 feet. I require a flow of 200 gallons per hour...which pump would I need? Primary concern = flow. Design centres around overcoming restrictions, back pressure and friction to achieve desired flow. Even in hydraulic systems, contrary to popular belief, the design rarely has pressure as its primary concern, it mostly is designed to achieve a controlled movement (flow) overcoming back pressure and even in clamping applications where pressure does become a component of primary focus, the pressure is achieved at flow as the flow is oil bled off back to tank at the pressure resulting from the restriction. Because hydraulic system pump design is for a fixed flow, pressure is bled off to tank if it reduces flow to prevent damage because oil cannot be compressed.

    Gary BarisGary Baris16 giờ trước
  • Always learning something new coincidentally I needed to get a pump or my project thanks for this video and insight

    delvin requenadelvin requena18 giờ trước
  • Public water systems usually use gravity tanks to provide pressure and tank level sensors determine when the pumps turn on and shut off to fill the tank. That way they aren't running non stop. Many high rise buildings use pressure tanks or a gravity tank on the upper level and/or lift pumps to provide water volume/pressure.

    sd dirtsd dirt18 giờ trước
  • When you drown, its not the oxygen that kills you, it's the hydrogen....

    sd dirtsd dirt18 giờ trước
  • depends on the pump....

    Master80059Master8005920 giờ trước
  • "It's not the pressure that kills you, it's the flow." And I assume positive displacement pumps can stall at high pressure.

    soiung toiuesoiung toiue20 giờ trước
  • Great video. I hope it was understandable even for people, who don't have background in this matter.

    FirewolfczFirewolfcz21 giờ trước
    • RSE Plumber in Canada, Great video! 👍🏼👍🏼

      soiung toiuesoiung toiue20 giờ trước
  • Basically, it's the same question as telling whether an electric source shall be described by its Thévenin or Norton equivalent.

    thafffthafff22 giờ trước
  • I didn't watch the video, I didn't read any of the comments, and I'm not taking a side. But I'm here to tell you that you're all totally wrong and basically fundamentally bad people who should be ashamed.

    Godfrey PoonGodfrey Poon22 giờ trước
  • Accuracy and brevity rarely coincide.

    JunkyardFootJunkyardFoot23 giờ trước
  • My new job has a lot to do with pumps, flow rate, differential pressure These videos have helped me tons, thank you for making these fun and entertaining

    VICTORdoommVICTORdoomm23 giờ trước
  • If you had a valve half way up and pinched it off some. Would that help to get it higher? So you would be cutting the flow a little bit but putting some back pressure on it to beat the head pressure? I work in a refinery and I am trying to wrap my head around why we pinch the discharge of a pump to stop it from cavitation and on a cooling water system why we have the return to the water basin pinched in to create that back pressure.

    B FinleyB Finley23 giờ trước
  • Is there not a maximum height for a positive displacement pump? Surely if there is enough pressure in the line the PDP won't be able to push any more liquid into it.

    MinnowMinnowNgày trước
  • Boy do I wish we had an engineer like you, 20 years ago. I was an electrician that seemed to have absorbed/dumped into the water system where I worked. (Now retired) They had 4 vertical 1000 gallon / minute Deming pumps that outputted through 8” ID pipe, into a 14” header/collector pipe, sending water from a settling pond, ¼ mile back to the main plant. They kept adding more and more equipment, that needed cooling water, so the engineer kept adding pumps. No matter what he did, the pressure and the volume, ¼ mile away never increased. (Eventually up to 8 pumps) I tried to show him the folly of forcing more water through that same 14” pipe was futile, with an impeller driven pump, but the engineer looked at me as if I was a moron, till he finally got to see the amperage going down on each pump motor as other pumps were manually turned on. (Took 4 clamp-on's at once to visualize it) If you would, show how an ammeter is a good tool to check and set up pumps, check wear on impellers, and the need to set the pumps at 100% load (rather than 70-80%), to get the best balance out of multiple pump systems. Some of the newer people to the field would benefit. Most people see pump curves, and just shrug their shoulders. Setting them up is fascinating though, especially when the mechanic foreman comes to you, with his budget for the year, and asks, which pump is showing the least efficiency, and you can show him with an ammeter, and a pressure gauges, which impellers are wearing the most, in parallel multi-pump systems. I’d be glad to feed you my notes, but it sounds like you have all you need. Thanks, Mike

    Mike TrisselMike TrisselNgày trước
  • "Internet pump enthusiasts" 🤣

    MggWMggWNgày trước
  • Looks like I just found a new favorite VIworld channel!

    Mark OMark ONgày trước
  • Hi Grady, maybe think about it this way: Pumps do work, i.e. use power over time, aka energy. Pressure is potential energy. Flow is the realization of time and work under the potential energy of the system.

    WillWillNgày trước
  • Pressure or flow? Well it rather depends upon if you have opened the valve or not and the type of pump. Centrifugal pumps - well the larger ones - are started against a closed valve to reduce motor load. They don't create any flow and only create the maximum design pressure. I'd argue that this makes them pressure creators. Positive displacement pumps work the exact opposite. They need to run against an open valve because they will move the liquid regardless of the state of the valve (or pipework) until something fails. That's by they are fitted with bypass PR v/vs. I'd say this makes PD pumps flow devices not pressure pumps.

    Mark ChisholmMark ChisholmNgày trước
  • Even someone in my class said "it's not the voltage that kills you, it's the current". I study electrical engineering

    Hasin AyariHasin AyariNgày trước
  • 😁👍👍👍👍😁

    MartinMartinNgày trước
  • As a plumber I really appreciate this video. You opened my eyes to new ideas, and I love pumps too. I work with hydronic pumps so we go for efficiency and longevity rather than high flow or head. There are issues however with placement that can impede or enhance cavitation and also entrapped air removal through traps or high points. Thanks again for all these great videos!

    Doc ManglerDoc ManglerNgày trước
  • Moree pumpss!!!

    Cheech MarinCheech MarinNgày trước
  • RSE Plumber in Canada, Great video! 👍🏼👍🏼

    MJ WMJ WNgày trước
  • Can you discuss pumps in series vs pumps in parallel?

    Cat22Cat22Ngày trước
  • This reminds me of AgentJzyZ clearing misconceptions in gas turbine engines…

    Yaofu ZhouYaofu ZhouNgày trước
  • 2:28 WIN BRAND NEW -i-P-H-O-n-E-1-2-----۞------------ 》》 𝐋𝐢𝐦𝐢𝐭𝐞𝐝 𝐓𝐢𝐦𝐞 《《 !❤️ 在整個人類歷史上,強者,富人和具有狡猾特質的人捕食部落,氏族,城鎮,城市和鄉村中的弱者,無`'守和貧窮成員。然而,人類的生存意願迫使那些被拒絕,被剝奪或摧毀的基本需求的人們找到了一種生活方式,並繼續將其DNA融入不斷發展的人類社會。 說到食物,不要以為那些被拒絕的人只吃垃圾。相反,他們學會了在被忽視的肉類和蔬菜中尋找營養。他們學會了清潔,切塊,調味和慢燉慢燉的野菜和肉類,在食品市場上被忽略的部分家用蔬菜和肉類,並且學會了使用芳香的木煙(如山核桃,山核桃和豆科灌木 來調味食物煮的時候 1620446674

    Mykel Melou DeleonMykel Melou DeleonNgày trước
  • Looking at those characteristic curves remindes me of "Supply" and "Demand" curves from Economics, where the axis are x=quantity and y=price. Surprisingly, the Supply curve corresponds to the System characteristic, while the Demand curve corresponds to the Pump curve.

    Edward BlairEdward BlairNgày trước
  • too long vid for basic things

    FFFFNgày trước
  • A more catchy, less useful phrase: *Pump turn on, water go vroom* You can go ahead and use that one in serious pump discussions, I don't mind. ;)

    Daniel HaleDaniel HaleNgày trước
    • LOL

      MJ WMJ WNgày trước
  • This is a good way to understand circuits. P=IV

    Kevin LuoKevin LuoNgày trước
  • I have always HATED that "it's not the voltage that kills you. It's the current" saying. Have they never heard of Ohm's law?

    jogandspjogandspNgày trước
    • @Kevin Luo that's very arbitrary. All of those basic equations are rearrangements and substitutions of the same few variables. Personally, I find the equation V=IR to be much more instructive. It shows that at constant resistance, current and voltage are directly correlated. So as voltage goes up, so does current.

      jogandspjogandspNgày trước
    • The key equation is Power=current*voltage

      Kevin LuoKevin LuoNgày trước
  • this mans rapper name should be lil pump

    Thomas SearsThomas SearsNgày trước
  • This is bollocks, I teach hydraulics - as for voltage and amps, look at Electroboom for how high voltage doesn't kill.

    PaulPaulNgày trước
  • if i speak and you hear me, is it my sound youre hearing or is it just the vibrations of air my voice imparted to the air in front of it

    PharmdkeithPharmdkeithNgày trước
  • So if you need a specific and guaranteed flow rate go with a positive displacement pump, OK

    bpetnoibpetnoiNgày trước
  • As a EE: the flow is equal to the ratio of your pumps characteristic and system resistance.

    Sami HawasliSami HawasliNgày trước
  • We say, "Pump up the jam" at Smuckers.

    bill boydbill boydNgày trước
  • Bicycle pump?

    System AnalystSystem AnalystNgày trước
  • Excellent video. It explains in 10 minutes what it takes a year to learn at university. Jesus

    Juan AnesJuan AnesNgày trước
  • IT'S all about the discharge pipe

    11cyrus1111cyrus11Ngày trước
  • The parallels between electricity and water flowing in a pipe are extremely similar

    UOttawaScottyUOttawaScottyNgày trước
  • lol it is the current that kills you. I've taken 250k volts to the chest and walked away without even a burn. I'm not willing to take .5 amps.

    SkitchesSkitchesNgày trước
  • Current kills. end of story no disagreement amongst electrical engineers. People who are not engineer still debates thou. 50 ma through your heart you are dead(approx 200ma or more through body ;depending on size point of contact etc ,if right hand to left hand -phase to neutral short- lowers the amount to 50ma so-which can kill too .that is why 48v might kill you too (48v/1kohm(theoretical resistance of body) =48 ma ). for the i-diodes who does not believe you may read educational papers: i had a soldier while i was military who struck by high voltage line via direct contact of ladder. current jumped to him from an aluminum ladder and entered from his upper leg and exited from his lower leg. he has several burns and exploded flesh marks at entrance and exit but is still alive.( though other two guy who was holding the ladder at upper levels died horribly) thumbs up for the vid thou.

    Muhammed GundoganMuhammed GundoganNgày trước
  • I think the "catchy" answer is "it depends" :)

    Warren McGeeWarren McGeeNgày trước
  • It might be rocket science when you think that turbopumps are used in rocket engines... So, learn the pumps and go for rockets !

    Fada TeFada TeNgày trước
  • Small nit pick: the vertical line for your positive displacement pump is only accurate for a theoretical "ideal" pump. As you know, actual pumps behave in that manner over only a limited range. Great video, though.

    potterma63potterma63Ngày trước
  • As always, I appreciate that you have provided captions!

    GeneralStrykerGeneralStrykerNgày trước
  • Pumps don’t create pressure or flow. They just convert one kind of energy to another. Not really a catch phrase, just shows how inane this debate is.

    Reid LarsenReid LarsenNgày trước
  • how do I keep automatic booster pump from cycling on & off when set to max flow? The water in the pipes would just create a back pressure or maybe reverse flow too that close a valve that detects flow on max settings.

    fraginzfraginzNgày trước
  • Here's my attempt Pumpy pumpy go go

    Ryan DikdanRyan DikdanNgày trước
  • Of course it makes pressure. The spinny thing pushes whatever it touches.

    TheBlacktomTheBlacktomNgày trước
  • Welp I am in the market for some pumps. Thanks for a new good info!

    Joshua BliffenJoshua BliffenNgày trước
  • "Given a water tank of radius R and height H centimeters empty of any fluid, at a height of M meters above the ground, connected to a pump of P horsepower, via a pipe of diameter D inches, calculate: 1- The pressure of the water column at the end of the pipe, at ground level. 2- The time required for the pump to fill the water tank. 3- The total power consumption of the pump." I remember that one from Physics II in high school. The teacher thought he could troll us by mixing the units, but I managed to sneak a key question past him and the rest of the class. When he answered what I was expecting, I knew I was on the right track lol

    NighthawkNighthawkNgày trước
  • Sounds like an auto engine creates car motion, not torque.

    Norma RosalesNorma RosalesNgày trước
  • Centrifugal pump creates flow of liquid, and pressure is created by resistance to the flow

    D IndianD IndianNgày trước
  • Surely the motor connected to the positive displacement pump will slow down if there’s an obstruction in the downstream pipe so the characteristic curve won’t be quite vertical.

    Jonathan TannerJonathan TannerNgày trước
  • Pump creates pressure Pressure creates flow Flow is evidence of work done If no flow then fluid heats up as evidence of work done All industrial centrifugal pumps are started against a closed discharge valve to limit the load on the motor, once the motor is up to speed the discharge is opened to establish the desired pressure/flow required. If you take a positive displacement pump and try to run it against a piping discharge that is dead-ended but has sufficient pressure withstand capacity then all you will get is high pressure and a stalled motor. I.e Zero flow.

    brencostiganbrencostiganNgày trước
  • Great explanation 👏🏻

    Umberto Costa BitencourtUmberto Costa BitencourtNgày trước
  • would love to see a video covering impeller pumps. I worked at a valve shop where the serviced crude oil pumps and they used impellers to "pull" the fluid though. the multi stage versions also did a "crossover" so the pumps impellers pushed or pulled on each other instead of generating a huge thrust load to one side. might be an interesting episode.

    Adam BordelonAdam Bordelon2 ngày trước
  • Without having watched the video I'm going to say both. Just thinking about putting a fan in a pipe i imagine it would directly interact with the water and push it to create flow but i imagine that the rest of the water in the pipe would move due to the change in pressure.

    Eldon RiverEldon River2 ngày trước
  • Thank you for adding metric to your graphs. It's very helpful :)

    David ResinDavid Resin2 ngày trước
  • What drives the pump, creates pressure and flow.

    Richard TrevinoRichard Trevino2 ngày trước
  • The catchphrase made this video go into my funny playlist haha

    James WasserfallJames Wasserfall2 ngày trước
  • 3:12 finally an american youtuber who makes a graph for everyone!

    Fa31Fa312 ngày trước
  • High vacuum pumps are definitely flow - purging individual molecules; pressure is a side-effect (due to there being fewer molecules left in the vessel).

    Andy OwensAndy Owens2 ngày trước
  • Great video! I've recently got into computer water-cooling and a question that often comes up is: "does X pump have enough pressure for Y system" and the biggest worry is that pump won't be able to push water to top of the loop. The videos between xQc and Linus are a great example of this. I was wondering if you have an intuitive way of explaining why a closed loop, in terms of water height, doesn't depend on the pressure rating of a pump. (or maybe it does and I don't understand it either) I'm thinking of making a video to explain my thinking and hopefully help some people understand it better.

    Nathan SturgeonNathan Sturgeon2 ngày trước
  • presentation on cavitation.

    kolim jonekolim jone2 ngày trước
  • - "Do Pumps Create Pressure or Flow?" - *YES.*

    NIKOvbnNIKOvbn2 ngày trước
  • Seems like just about everything can be improved with googly eyes ^^

    NIKOvbnNIKOvbn2 ngày trước
    • This is a great explanation at pump system level. At detail level....Inside the centrifugal pump, the spinning impeller accelerates the fluid, which creates pressure within the

      kolim jonekolim jone2 ngày trước
  • This is like electrical engineering: A power sources voltage and current depends on the load. It has an open load voltage, which is its maximum head, and a shorter load current, which is its maximum flow.

    PepsiMagtPepsiMagt2 ngày trước
  • I've been using small pumps for 20 years to watercool my computers. From aquarium pumps to dedicated WC pumps, discharge head has always been a main consideration, especially when using small diameter tubes and high restriction waterblocks.

    AesmaAesma2 ngày trước
  • Would love a video about vacuum pumps

    Tim OrtTim Ort2 ngày trước
  • Yes

    Craig RobertsonCraig Robertson2 ngày trước
  • "Any complex physical problem has a solution that is simple, elegant, and wrong." Paraphrasing Einstein, I think. Even Einstein as a young man fell for the bogeyman of another fluid dynamics problem, the equal transition time fallacy of how wing profiles create lift; he proposed, as many do when they first hear it, a wing section with a wavy upper surface.

    HotelPapa100HotelPapa1002 ngày trước
  • What about diaphragm pumps?

    Peter GamachePeter Gamache2 ngày trước
  • Most pumps are rated in flow at a max lift . So it is consistent

    Corey McConnellCorey McConnell2 ngày trước
    • At max lift centrifugal pumps have no flow

      Practical EngineeringPractical EngineeringNgày trước