I've worked several departments from explosives to engineering, electrical and heavy equipment. I think this guy may be the best instructor I've ever heard.
Let’s face it most of the teachers are mostly by the book but doesn’t even have the clue what’s going on in the real world, this guys knows a lot and gave me instant understanding on the subject matter.. 👍🏼👍🏼
This is sooooo much better then spending 8h looking at an powerpoint! You need to see things move and a guy that knows how to explain to you in a simple way! perfect video! thank you very much for the help!
Awesome Explanation, we're just so lucky living in these times, finding a video from a brilliant guy Like Jack at our finger tips. Thanks for sharing it and wish you the best
Fantastic explanation. Had never heard pressure expressed as "the amount of resistance being overcome by the pump". Thank you for clearing up this concept.
Very useful! I keep this video on a 'rewatch' playlist that I revisit every time I need to dig up some lost knowledge , and I've come to this one many times over the years but never commented. Thanks a lot Jack!!
I can't count the number of people that tell me the pump makes pressure. I've tried to tell them it doesn't only to be called an idiot for thinking that. Thanks for telling me I am not. I will show these people this video. But I'm sure it will not be met with the enlightenment I'm hoping for. Some just can't accept basic hydraulic fact. Thanks again for the video and the explaination Jack.
Jack came to our site in Scotland 8 years ago and mapped our several hydraulic systems . He returned 2 weeks later with a course that set me up with the know how to solve the problems that came along. Funny thing is that we had a fault on a system when he was on site that no mater what we changed it turned out to be the big swash pump in the end . Top bloke and a top course.👍👍👍👍👍
Thank you so much for the kind comment! We enjoyed that trip so much - it was the first time I had been back to Scotland in over 30 years (and my wife's first time ever). So much had changed. But so much HADN'T. Great folks at that mill. I was welcomed warmly and treated like family. Scotland was every bit as beautiful as I had remembered, too! We have talked about that trip so many times and hope to return soon.
My hydraulics instructor at UTI over 30 years ago said this ; when you pee, that's flow. Now put your thumb over the hole, that's pressure. Simply put, flow against a restriction causes pressure.
Hey Jack I'm a medical student and the physics of circulation is basicly a lot like hydrolic system! A lot if your videos helped me, thank you!!!!!!! Keep doing what your doing =]
Very nice video . I want to ask of the pressure gauge reading at the pump outlet always indicate the resistance that the pump has to overcome in all pump cases ?
Thank you for your kind comment and question! Yes, you can consider pressure and resistance to be synonymous in a hydraulic system. If you remove all of the resistance, say, direct the outlet of the pump straight to tank, the gauge will read nearly 0 PSI (perhaps a small amount of pressure resulting from the resistance of friction in the piping).
Thanks jack, I'm a bus driver and have no need to know these things other than my curiosity. I have never seen a hydraulic schematic before but your explanation was absolutely brilliant. Once again, thanks to RUclips and videos like yours, my knowledge drum is more full!
I'm an electrician and I'm trying to explain to a young lad that has just joined our Company our hydraulic test rig. I've found this a very good example as not being my trade I understand hydraulics but struggle to teach it.
PSI comparable to Voltage, what's the potential FLOW comparable to Amps, how much is going through Until there's resistance or a load, not much to measure
So the purpose of the pilot line is to return oil that doesn't make it through the RV to the main line? Is it also not common for the pilot line to return back to the reservoir? Excellent video. Thank you for your time.
@@JackWeeks I had an argument about this, well, discussion really, with a guy who was supposed to be the supervisor. He didn't get that pumps that "do" high pressure, are simply capable of producing flow against a higher resistance than a low-pressure pump.
Everyone at work has a knob turner, and that knob turners name is "NOT ME". How very true. I firmly believe combining technical information with REAL WORLD analogies (and humor) is the best way to actually teach/learn. I wouldn't go as far as saying he's my fucking hero (though that comment made me laugh) , but we definitely need more people like Jack Weeks.
Hi , hope you are good. Wanted to know your views on Pressure reducing valves. When I checked, seems that they all have internal leakage through their pilot line. I mean , for a pressure reducing valve to work , the pilot line must drain oil to tank. So if any pressure reducing valve is connected to an accumulator, it will drain the accumulator till the preset pressure is reached and pilot drain flow will stop ! Am I right? Can pressure reducing valves be used with accumulators? For example, can we have a 3 way pressure reducing valve without internal leakage? Do we have any models of 3 way pressure reducing valves without leakage? Does leakage happen when valve is off ? For e.g suppose I have a 3 way proportional pressure reducing valve; when valve is off , output pressure is zero. If this valve is connected to an accumulator, will it drain all accumulator oil little by little? Will leakage occur when valve is off ? Thanks. Kind Regards.
Hi Nadeem. No, I don't think I would recommend using a pressure reducing valve in an accumulator dump line. Depending on the valve, it could easily be constructed to leave some back pressure in the accumulator. Best to use either a flow control or a gate valve. Usually it's best to dump the accumulator slowly, too, so don't open your flow control too far. Keeps turbulence from the reservoir so you don't stir up sludge when the accumulator is dumped. Thanks for your comment!
Thank you for your comment, Mandar. Essentially, a gear flow divider is simply a set of hydraulic gear motors that share a single shaft. Flow that is input will be split equally between the outputs, i.e. a 30 GPM input will result in exactly 5 GPM at each output. For most applications, there should be crossport relief valves at each output to allow for some "slip" in the circuit. I don't know what type of actuators you are using, but say for example that you are moving six cylinders in unison. The flow divider will ensure that each cylinder will receive exactly the same rate of flow, but no two cylinders will bypass the same amount. Thus, if there are no crossport relief valves, no two cylinders will reach the end of their stroke at exactly the same instant. This will not be noticeable at first, but after a while they will be out of sync with each other. With the crossports installed, once the cylinder with the least amount of internal bypass reaches the end of its stroke, the associated crossport will open up to allow the next cylinder to complete its stroke and so forth. The crossports are usually integral to the flow divider and factory preset. If so, you will be able to tell by the adjustment at each outlet port. If they are not present, they must be installed separately. Each crossport should have its inlet connected to the outlet of the flow divider and its outlet connected to the flow divider inlet. Hope this helps!
Absolutely ! when I visited sight I observed it to be Delta Hydraulic Company gear flow divider , HPR heavy duty series with relief valves , 200 bar pressure. my observation is as follows , two cylinders raise one scissor lift and these two cylinders are attached to a rigid link.There are three such lifts identified as 1 , 2 and 3 viz, serial no 1 and 3 are in synchronization while as no 2 goes faster during extension and lag behind during retraction stroke. When I put some load on lift on 1 , it goes faster than other two while no 1 retracts , no 2 and 3 extends. I am confused. Could you please extend your help. This matter is urgent for me as plant is under scheduled shutdown process.
This is because any cylinder will retract faster than it extends. Since the cylinder rod displaces oil in the cylinder, more oil is required to extend it than to retract it. If the same flow rate is provided in both directions, any cylinder will always retract faster than it extends.
Actually, as I reread your description, I think I was misunderstanding you. If I understand correctly, you are saying that the speed changes when you add a load? Can you send me a schematic of the circuit? My email address is jack@gpmhydraulic.com
Hello Mr. Jack, very much clear informative video, by the way flow & pressure relation shown in this video will be same if I consider positive displacement pump?
Great video, thank you! I do feel like the statement at 0:00:45-0:00:52 is a little incomplete, although it is a consistent statement. I would think the pump provides Energy over time (HP) to the water, and this energy is transferred in either flow or pressure depending on the resistance in the system. Nit-picky of me, but just something that peaked my interest. Let me know if I'm seeing this incorrectly!
Hi, Aaron - thanks for your comments! I think I understand what you are saying (but maybe not!). I think that you are saying that energy is transferred from the pump to the liquid. If so, you are absolutely correct. This is one of the purposes of the fluid, to transmit energy through the system. Perhaps the way I said it suggested that the pump does not transfer energy? But it certainly does. But while the pump does transfer energy, this should not be construed as the pump putting pressure in the system. The words “pressure” and “resistance” should be considered to be synonymous in this instance. If there is no resistance, there will be no pressure. The gauge tells only the resistance that is currently being overcome. Think of it as picking up an object. Once the weight of the object has been overcome, there is no way to use any more strength in your arm to pick it up. Someone stronger than I can pick up a heavier object than I can, but if we are both picking up the same object, we both use exactly the same strength. Like flow overcoming resistance, the object weight is determined solely by its mass, unaffected by the ability of the lifter.
Nice Video! Sorry for butting in, I am interested in your initial thoughts. Have you researched - Marnaavid Unexplainable Intervention (do a search on google)? It is an awesome exclusive product for learning how to hack your flow state without the headache. Ive heard some pretty good things about it and my m8 at last got cool success with it.
@@hemanthchavan2819 My pleasure, Hemanth. Sorry that I didn't convey enough about flow, but all that I was really trying to get across was that flow describes the volume of fluid being delivered, whereas pressure describes the amount of resistance to be overcome by the flow. I had considered elaborating to some degree about how the volume of flow would determine the speed of the actuator and that the weight of the load on the actuator would determine the resistance (and therefore pressure) in the system, but it seemed as though that might be going off on a tangent.
@@JackWeeks Thank you for your reply. For instance, if you have a fixed displacement pump, running at a constant rpm and you are not sure whether the pump displaces the full flow rate or it has leaks with reduced flow but you are sure that it has the capacity to overcome the pressure build up by any resistance. So in this case, how to determine that the displacement is actually good or the pump is still performing well with reduced flow or low flow and leaks, provided no flow meter in the circuit. I hope you will understand my concern and share your valuable experience. In short, I get the pressure correct but I am not sure whether the flow rate is delivered correct.
@@hemanthchavan2819 If you have no flow meter (and do not wish to add one for diagnostic purposes), it is not as easy to measure the condition of the pump, but it can still be done. If the pump is becoming worn, it will lose flow (and heat up) under load. Even a bad pump will deliver its rated flow (or very nearly so) if there is little or no resistance. So try moving your actuator(s) with no load and time how fast it moves. Then try it under load. On most industrial machines, the design will require 75-90% of the pump flow, so if the actuator slows more than 10% or so, you might consider replacing the pump. Naturally, if your specific machine functions satisfactorily at a slower speed, it may not be necessary to replace the pump until it is more worn than that. Bear in mind however that the pump is not the only component that can affect speed with an increased load. The prime mover can cause speed reduction under load as can bypassing cylinders, motors, and pressure controls. This is the advantage that a flow meter can provide - all other components can be eliminated by measuring flow directly and using the relief valve to simulate the load. Then a reduction in flow can only be caused by either the pump or the prime mover. Usually bypassing components will also generate heat, so it is a good idea over time to check the temperature of components that can affect speed so that if only one of them begins operating at a high temperature, it can be a good indication of wear. Hope this helps!
I want to try understand how I can get more pressure...or is it flow LOL, through my shower head and faucets at my house. We're on a well. We pump from the well into a pressure tank. Would your "Trouble Shooting Hydraulic Pumps" course, help me understand how my system works?
I'm sure that it would - in the hundreds of times I have taught that class, I've never had a student who didn't feel enlightened by it. But the short answer to your question is probably going to be either a higher flow submerged pump or an additional inline pump. The latter may be the less expensive solution, particularly if you have an especially deep well or a very long run from your well (or both, as I did at a house I used to own. The auxiliary pump did the trick!) Hope this helps!
I learned a lot - thanks for the explanations; the accompanying coordinated graphics were excellent and very helpful. One observation, though - at about 4:55 when you start to talk about the manual valve and its graphic symbol, I found that counter-intuitive. I expected that since the "bowtie" graphic symbol was not colored in, that meant that there was no flow (ex.- the other arrowhead symbols for the pump and other valve are colored in, and represent flow). Other than that, it was an excellent tutorial. Thanks, Jack!
Thank you for your kind comments! Actually, there is no rigidly adhered to "standard" method of indicating an open or closed manual valve. Some draftsmen fill it in to indicate it is normally closed, some turn it sideways, and I'm sure there are others that I have yet to encounter - most of the time on our schematics we label it "NO" or "NC" and follow it up in the component description to maintain clarity.
GPM Hydraulic Consulting Turning it sideways (and leaving it uncolored) for a closed manual valve would be even more intuitive IMO since that would show a physical break in the linear flow "circuit" - much like how that pressure-operated valve symbol is not initially lined up with the linear "circuit." Just my 2 cents... Thanks, again.
Jack i know this is a big ask so i understand if your not able. I have a hydraulic system (for you extremely basic) but would love to understand how the whole system works, not only for troubleshooting but also just to understand how it works. Would i be able to email you pictures/info and you could explain the operation. Again i know its a big ask so i understand if your unable but it never hurts to ask and i love understanding how a system actually works. Thanks in advance whichever your response is, im hooked on your teaching videos. Brian
Thank you for your kind comments! Yes, I would be glad to help. Email me any time at jack@fluidpowerlearning.com (GPM Hydraulic Consulting is no longer in business, so I am on my own now).
@Jack Weeks Jack you made my day more than you know. So i give as much info as possible i will email you tomorrow so i can get pictures together and as much info to give you as possible to try and save you as much back and forth as possible. I will include in the subject line pretty obvious its coming from me. You have me excited like a little kid Jack so thank you so much.
Hi Jack, the message seems to be that the resistance which the pump has to overcome to maintain flow is where pressure comes from. My question is: Doesn't the source on the influent side of the pump also contribute to the pressure gauge reading on the effluent side?
Thank you for your comment! I'm not certain that I understand your question, but I think you are asking if the outlet pressure of the pump can be changed by changing the suction pressure. No, it can't. Regardless of the suction pressure, if there is no resistance downstream of the pump, there will be no outlet pressure. And, once the downstream resistance has been overcome, changing the inlet pressure will not affect the outlet pressure unless it causes the pump to stall. I hope this helps!
Hi Jack, This is a great video. I was wondering what would be the case for a non-positive displacement pump? How the pressure and flow rate can be varied for such pump? Thanks, Manjiri
Thank you for your comment! The principle would remain the same whether the pump is positive displacement or not. Or, for that matter, whether the pump is fixed or variable displacement. The pump still delivers flow and the pressure is determined by the amount of resistance that is overcome. A non-positive displacement pump (such as the water pump on your car engine) will not maintain an output proportional to the speed of its drive motor because it has relatively high internal clearances. Thus, the higher the RPM and the greater the resistance, the more the pump will bypass. By the same token, its flow can be blocked without serious danger.
Jack can you explain this using bernoulli's equation, if we decrease the diameter of the pipeline according to bernoulli's equation static pressure should decrease, but according to this video pipeline with small diameter gives high path of resistance so pressure guage reads high pressure, kindly help me clearing this confusion.
Thank you for your question, Hassan! Let me see if I can clear up any misunderstanding. In its simplest form, the Bernoulli equation states that static pressure + dynamic pressure = total pressure. A steady, unchanging flow is assumed. It is really more for measuring fluid velocity, particularly through a nozzle. The principle remains, however, that pressure is a measure of resistance. As the orifice changes, the pressure drop across the orifice changes in inverse proportion. Thus, the smaller the orifice, the greater pressure drop across it, assuming that the flow remains constant. The Bernoulli principle is really an expression (or, perhaps, "example" would be a better word?) of the Conservation of Energy law. Hope this helps, and thanks for watching!
Hi Jack, thanks for the video, I found it really informative. I stumbled on it after trying to understand the difference between pressure and volume, or flow I guess as you say. I was watching a video on a fire hydrant, which peaked my curiosity on what sort of pressure they run on. I assumed a very high pressure, as when on they move a LOT of water. I was surprised to find out it seems to normally be about 50 psi? I know at work our fire supression system is 120 psi of water pressure through 2 inch pipe. It also moves a lot of water when activated. I cant say I fully understand yet, for instance 60psi through my garden hose I can spray water ~20 feet, but that fire hydrant moves substantially more water, much farther with the same psi. I'll understand eventually lol. I am just a layman who likes to understand how things work. Your video has been enlightening, thankyou.
Thank you for your comment! Yes, that is a common misconception that pressure at a fire hydrant must be significantly higher than that at your house. Another common error (sort of a corollary) is that you use more water when working with a pressure washer than with just a hose nozzle. In fact, only a fraction of the water is used with the pressure washer. The distance the water will travel is determined by the power generated, typically measured in hydraulic horsepower. Hydraulic horsepower is the product of two factors, pressure and flow. In other words, horsepower = pressure x flow. If we are using English units of measure, of course, a constant is required since PSI (pounds per square inch) and GPM (gallons per minute) are not compatible. The constant that makes them work together is 0.000583, so the horsepower formula is: HP = GPM X PSI X 0.000583.
hi , i have an old Atom G 999 clicker press with a 2hp 3phase motor running @3600rpm.Im planning to reduce its rpm using a VFD. .im wondering what will happen if i do . Thanks in advance...your video is awesome.
Well, if you reduce its RPM, the flow will be reduced and therefore your press will move more slowly. I cannot say whether your VFD will generate sufficient torque at the new RPM, though. That is a question that can be better answered by the manufacturer of your electric motor.
I keep going round and round with these concepts due to the high level of conflict between manufacturers and engineers alike; I believe the primary reason is due to inconsistency with the term "pressure" (not using prefixes static, total, hydrostatic etc). Perhaps answers to a few questions can help to quell these issues: Is the pressure gauge in the schematic above a differential pressure gauge or a standard one? If it is a standard one (type Bourdon or otherwise), how can pressure (gauge) in a U-tube manometry situation be equal to hydrostatic head but be 0 in this situation? Shouldn't the pressure in the system be equal to P (tank) + P (developed due to resistance to flow)?
Thank you for your comment! While it is true that a standard gauge (which is the type used in the video) would indeed be subjected to a small amount of pressure (largely overcoming gravity, atmospheric pressure and friction), it would certainly not be enough to register. The point of the video however is to illustrate that the pressure does not originate at the pump, it is the result of overcoming resistance, all of which is external to the pump. The lack of pressure is therefore usually not caused by pump wear as so many assume. The points you make are quite valid - but are better left for a different video. Had I addressed them, it would have confused the issue and made the video less useful to the troubleshooter which, after all, is its primary purpose. Perhaps in a future video we may address the difference between PSIG and PSIA. This could provide the opportunity to discuss P (tank) + P (flow resistance) and indeed would be useful to the fluid power troubleshooter, particularly in pneumatic systems. Do you think that would have any appeal? Thanks again for taking the time to comment!
@@Gpmhydraulic I know a lot of time has passed since then but I didn't realise you had actually replied to me. It is only when Xavier below replied that I received the notification. Anyhow, seeing as though I never did it initially, I wish to thank you for the great content you had provided free of charge. At the time I was studying Mechanical Engineering at a British University and, as you may well know, the higher-ups use pressure, flow and such terms loosely without ever quantifying what exactly they mean. When pressed, they are rarely able to clarify as it seems quite a few don't understand the distinctions themselves! Regarding making more videos, I would honestly appreciate it immensely. Purely out of interest's sake and the fact that theory is discussed from a practical perspective with a dose of dry humour. Have a good day!
@@YG-be9gl Thanks for your kind words! Since the closure of GPM due to the effects of Covid, I have semi-retired. I have continued to do training and consulting on a freelance basis in my "spare" time, but have found since so many plants have reopened their doors to visitors that now I am working at least as much in my "retirement" as I did when I was employed! I'm hoping to find time to make some more videos, though, because I enjoy doing them and so many folks appreciate them and tell me they find them helpful. Hopefully I will find the time to do some more of them.
Your videos really help me to have a better understanding of hydraulic function.Thank you! In this tutorial on the diagram directly north of the pump is a smaller circle with an arrow, it's function/meaning was never addressed yet I did observe that once the regulator opened the arrow direction inside the circle moved also. Would you please explain what that symbol represents here and why the arrow moved? Thanks again! I am in the profession of industrial maintenance and our team has very little knowledge of hydraulics. I am currently trouble shooting some equipment and like the idea of not being a "parts changer" if the cure can be an adjustment that perhaps ol "not me" may have had a hand in!
Sorry, I suppose I could have explained that one a little better - you aren't the first person to ask. That is a pressure gauge. Note that it did not move when the hand valve was open, because there was no resistance in the line, thus no pressure. Once the hand valve was closed, the resistance of the relief valve had to be overcome, thus there was pressure and therefore movement of the gauge.
Excellent question. The pilot line is a very small line that delivers a pressure signal to the valve. In this particular case, the valve is a relief valve. The pilot in most relief valves is internal (even though the symbol is drawn such that it may appear to be external).Whatever pressure is present in the main line will also be present in the pilot line. Pressure in the pilot line acts upon the internal spool (or plunger, depending on the type of relief valve) and, once the pressure reaches the amount necessary to compress the internal spring, will shift the valve open. Fluid then returns to tank through the valve. Hope this helps! Thank you for your question.
HI my name is Brian. Am a technician in Kenya. Thank you for your tutorials. I have this question; how do you overcome the flow/pressure from a bigger pump feeding a 4''pipeline with a smaller pump jointing this pipeline with a 0.5'' pipe. Basically the second smaller pump is trying to inject its fluid into the bigger pipeline but is overcome by the bigger pump and so doesn't achieve this.
Thank you for your comment/question, Brian! Clearly the pressure in the 4" line is above the pressure developed by the smaller pump. I suppose the question would be, where is the flow from the smaller pump going if not into the pipeline? We need a bit more information here. You don't say what type of medium is being used here, or the purpose of injecting fluid into the larger pipe. Are the fluids in both pipes the same? For instance, is the smaller pump used to inject liquid soap into a larger water line? Or are we using the smaller pump simply to augment the flow of the larger pump? Are both pumps positive displacement? If so, they would likely be protected by relief valves. If the smaller pump is positive displacement and the pressure is too high in the larger pipeline for the smaller pump to deliver, the flow of the smaller pump must be dumping across a relief valve. It may simply be a matter of setting the relief valve protecting the smaller pump to a higher setting so that the path of least resistance is to inject into the larger pipeline rather than dump across the relief. If however the smaller pump is not positive displacement, the pressure in the larger pipeline is too high for the smaller pump to deliver. In that case, the smaller pump would begin to bypass across its internal clearances. If this is the case, you will need a different pump to deliver flow through the 0.5" line. Hope this helps!
Hi thanks for replying. Now the fluid in the 4 inch pipe is petrol and the smaller pipe is an additive injection to mix with that fuel to a set ratio. I'll have to find out if the pumps are positive displacement, but I suspect both are. The mech team tried fix a non return valve on the smaller pipe right at the inlet to the 4 inch. We are yet to test and hope it will work. Do you think the non return valve will work? Or we must use the thermal relief valve?
@@Bojak079 The non return valve will keep reverse flow from entering the 0.5" line and turning your smaller pump backwards, but I doubt it will help overcome the pressure in the 4" line. In order to add flow, the pressure in the 0.5" line needs to be higher than that in the 4" line. The smaller pump should be able to withstand the resistance in the 4" line if it is positive displacement. If there is not already a pressure relief valve in that 0.5" line, the smaller pump must not be positive displacement. It must be behaving similarly to the impeller type water pump in an automobile engine when the thermostat is closed - bypassing internally once pressure reaches a certain point.
I've worked several departments from explosives to engineering, electrical and heavy equipment. I think this guy may be the best instructor I've ever heard.
As an electrician looking to learn hydraulics your presentation was one of the best I have seen on RUclips for any kind of training.
Thanks !!!!!!!!
Thank you so much for your kind comment!
Let’s face it most of the teachers are mostly by the book but doesn’t even have the clue what’s going on in the real world, this guys knows a lot and gave me instant understanding on the subject matter.. 👍🏼👍🏼
What a nice thing to say! Thank you very much.
I studied mechanical engineering in a top university, this guy gives me a whole new perspective on fluid mechanics in 7 minutes
that's because you don't learn anything in school
That's because you were too busy chasing fats girls and not paying attention in class
@@hueroski rofl
Great of you to comment.
@@rubixcubesolve thats so true. it only tests your ability to read things and recite based on short term memory
Honestly this guy is the BEST. i hope more and more videos of his lectures get posted. PLEASE
Thank you very much! Yes, stay tuned for more!
This is sooooo much better then spending 8h looking at an powerpoint! You need to see things move and a guy that knows how to explain to you in a simple way! perfect video! thank you very much for the help!
Thank you!
You have no idea how incredibly helpful this has been to me! Thank you so much, Jack!
What a kind comment - thank you!
Awesome Explanation, we're just so lucky living in these times, finding a video from a brilliant guy Like Jack at our finger tips.
Thanks for sharing it and wish you the best
Thank you very much for your kind comment!
Fantastic explanation. Had never heard pressure expressed as "the amount of resistance being overcome by the pump". Thank you for clearing up this concept.
Very useful! I keep this video on a 'rewatch' playlist that I revisit every time I need to dig up some lost knowledge , and I've come to this one many times over the years but never commented. Thanks a lot Jack!!
Thanks, D! I'm glad it has helped!
I can't count the number of people that tell me the pump makes pressure. I've tried to tell them it doesn't only to be called an idiot for thinking that. Thanks for telling me I am not. I will show these people this video. But I'm sure it will not be met with the enlightenment I'm hoping for. Some just can't accept basic hydraulic fact. Thanks again for the video and the explaination Jack.
And thank YOU for the kind comment!
Best explanation of flow vs pressure I have ever viewed!
I couldn't I agree with you more on that one..an excellent presentation. just wish we had you tube during my varsity years...
Jack came to our site in Scotland 8 years ago and mapped our several hydraulic systems . He returned 2 weeks later with a course that set me up with the know how to solve the problems that came along. Funny thing is that we had a fault on a system when he was on site that no mater what we changed it turned out to be the big swash pump in the end . Top bloke and a top course.👍👍👍👍👍
Thank you so much for the kind comment! We enjoyed that trip so much - it was the first time I had been back to Scotland in over 30 years (and my wife's first time ever). So much had changed. But so much HADN'T. Great folks at that mill. I was welcomed warmly and treated like family. Scotland was every bit as beautiful as I had remembered, too! We have talked about that trip so many times and hope to return soon.
The most clarifying explanation on the topic i’ve heard, thank you sir!
Really helpful. I'm a garbage truck driver, so hydraulics are a major part of the vehicle. This is a great video sir!
Thank you, Andrew!
As a dead weight tester manufacturer, the video is very good to understand pressure and flow for dead weight tester use. Thanks
Great, during 8 years I had never noticed and nobody told me. Thanks for sharing this priceless information.
Thanks!
great first step explanation, old time technician but today I learned the best first lesson about hydaulic, thank you
Thank you for your kind words, Jimmy!
I love it when people can explain things simply and clearly - it's a true talent.
Thank you very much, Lymey!
Jack Weeks is very clear and concise in explaining this difference. I look forward to visiting his website and learning more. Anastasia A.
My hydraulics instructor at UTI over 30 years ago said this ; when you pee, that's flow. Now put your thumb over the hole, that's pressure. Simply put, flow against a restriction causes pressure.
Sounds like a good example to me.
George Kuersten 🤣👌🏾
thats usually painful too, u do feel that mechanical pressure against the wall of your pipe
I think that's what you call a UTI infection...
They are right, indeed.
Excellent Jack, less part exchangers and more troubleshooter! Genious
Elio Gonzalez Thanks Elio!
7 mins to explain one of the most confusing(at least I thought it was) concepts in the world. Thank you.
Thank you very much for your kind comment!
Just simple excellent way of explaining
greetings from egypt
Thank you, Mohamed!
Great guy and very easy understanding wish you all the best and stay safe
You are a great teacher.
Thank you very much, Pablo!
This makes the basics very clear. Great work Sir
PULKIT GARG, thank you for your kind comment!
Jack, you are a very good teacher and an excellent presenter. Thank you.
Thank you, TeamMoteck, for your kind comment!
Hey Jack I'm a medical student and the physics of circulation is basicly a lot like hydrolic system! A lot if your videos helped me, thank you!!!!!!! Keep doing what your doing =]
Thanks, Inbar!
Very nice video . I want to ask of the pressure gauge reading at the pump outlet always indicate the resistance that the pump has to overcome in all pump cases ?
Thank you for your kind comment and question! Yes, you can consider pressure and resistance to be synonymous in a hydraulic system. If you remove all of the resistance, say, direct the outlet of the pump straight to tank, the gauge will read nearly 0 PSI (perhaps a small amount of pressure resulting from the resistance of friction in the piping).
Thanks jack, I'm a bus driver and have no need to know these things other than my curiosity. I have never seen a hydraulic schematic before but your explanation was absolutely brilliant. Once again, thanks to RUclips and videos like yours, my knowledge drum is more full!
Thank you for your kind comments, Alex! - Jack
Great tutorial, thank you for sharing your knowledge, God bless and more powers.
Thank you very much!
You`re a good teacher, Mr. Jack Weeks!
Thank you very much!
Your knowledge makes me want to learn more about fluid power, and I'm just an electrical student right now.
Thank you very much! We're happy you enjoyed it.
I'm an electrician and I'm trying to explain to a young lad that has just joined our Company our hydraulic test rig. I've found this a very good example as not being my trade I understand hydraulics but struggle to teach it.
Thanks - glad we could help!
PSI comparable to Voltage, what's the potential
FLOW comparable to Amps, how much is going through
Until there's resistance or a load, not much to measure
So the purpose of the pilot line is to return oil that doesn't make it through the RV to the main line? Is it also not common for the pilot line to return back to the reservoir? Excellent video. Thank you for your time.
Great video Mr. Weeks, very efficient way to explain pressure concepts
Thank you very much, Marcos!
Excellent explanation......even this electrical engineer understood.
Thanks, Geoff!
Clear, concise, brilliant. "Who changed that?" "Not Me" So true.
Thank you very much for your kind comment!
@@JackWeeks I had an argument about this, well, discussion really, with a guy who was supposed to be the supervisor. He didn't get that pumps that "do" high pressure, are simply capable of producing flow against a higher resistance than a low-pressure pump.
@@ATPLTKI Well, I'm glad you found it helpful!
Awesome stuff here. Trying to learn more about the hydraulic system on the Zamboni. This helps alot. Thank you.
Thank you so much for your kind words!
bless you Mr Weeks this done saved me a lot of trouble
Everyone at work has a knob turner, and that knob turners name is "NOT ME". How very true. I firmly believe combining technical information with REAL WORLD analogies (and humor) is the best way to actually teach/learn. I wouldn't go as far as saying he's my fucking hero (though that comment made me laugh) , but we definitely need more people like Jack Weeks.
Thanks, Tony!
Brilliant and simple explanation..
Dude... You're the man...
Great video, dude. Simple, practical descriptions of hydraulic concepts.
+Gossamer Socks Thanks!
Excellent explanation Sir.
I like his way in explaining the difference between pressure and flow .He is an awesome instructor
Amrou Abdelghani Thanks!
Great, thanks . I never heard this information
Best video ever explaining this stuff, thumbs up, hands down
Thank you Jack, very informative.
Thanks for the video Jack!
My pleasure! Glad you enjoyed it.
This was the easiest shit to understand, coming from someone who doesn't know the first thing about this. Well done!
Excellent training. If I were in his company, he would be on my contact list.
Thank you very much, Rev!
Excellent jack! Please make more of these!
Great communication technique Jack. I am a total idiot when dealing with this stuff but I now know a bit more. Thanks
+Bruce Bailey Thanks, Bruce!
@Hello Bruce Bailey, How are you doing?
A most excellent explanation!!!
Thank you, Emmanuel!
Thank you Jack for your presentation ... really helps understanding the difference between flow and pressure... once again thank you.
Ray
+Ray Bazan Thanks for your comment!
@Hello Ray Bazan, How are you doing?
Thank you very much for this video, very well presented! Was very helpful in preparing for my job interview.
Thank you for the kind comment - glad you found it informative!
Hi , hope you are good. Wanted to know your views on Pressure reducing valves. When I checked, seems that they all have internal leakage through their pilot line. I mean , for a pressure reducing valve to work , the pilot line must drain oil to tank.
So if any pressure reducing valve is connected to an accumulator, it will drain the accumulator till the preset pressure is reached and pilot drain flow will stop !
Am I right? Can pressure reducing valves be used with accumulators? For example, can we have a 3 way pressure reducing valve without internal leakage?
Do we have any models of 3 way pressure reducing valves without leakage?
Does leakage happen when valve is off ?
For e.g suppose I have a 3 way proportional pressure reducing valve; when valve is off , output pressure is zero. If this valve is connected to an accumulator, will it drain all accumulator oil little by little? Will leakage occur when valve is off ?
Thanks.
Kind Regards.
Hi Nadeem. No, I don't think I would recommend using a pressure reducing valve in an accumulator dump line. Depending on the valve, it could easily be constructed to leave some back pressure in the accumulator. Best to use either a flow control or a gate valve. Usually it's best to dump the accumulator slowly, too, so don't open your flow control too far. Keeps turbulence from the reservoir so you don't stir up sludge when the accumulator is dumped. Thanks for your comment!
@@JackWeeks thank you 🙂
Beautifully illustrated. Thank you
Thank you so much for your kind comment!
Nice explanation , can you tell something on gear flow dividers (one input and six output) and how to install it in the hydraulic circuit
Thank you for your comment, Mandar. Essentially, a gear flow divider is simply a set of hydraulic gear motors that share a single shaft. Flow that is input will be split equally between the outputs, i.e. a 30 GPM input will result in exactly 5 GPM at each output. For most applications, there should be crossport relief valves at each output to allow for some "slip" in the circuit. I don't know what type of actuators you are using, but say for example that you are moving six cylinders in unison. The flow divider will ensure that each cylinder will receive exactly the same rate of flow, but no two cylinders will bypass the same amount. Thus, if there are no crossport relief valves, no two cylinders will reach the end of their stroke at exactly the same instant. This will not be noticeable at first, but after a while they will be out of sync with each other. With the crossports installed, once the cylinder with the least amount of internal bypass reaches the end of its stroke, the associated crossport will open up to allow the next cylinder to complete its stroke and so forth. The crossports are usually integral to the flow divider and factory preset. If so, you will be able to tell by the adjustment at each outlet port. If they are not present, they must be installed separately. Each crossport should have its inlet connected to the outlet of the flow divider and its outlet connected to the flow divider inlet.
Hope this helps!
Absolutely ! when I visited sight I observed it to be Delta Hydraulic Company
gear flow divider , HPR heavy duty series with relief valves , 200 bar pressure.
my observation is as follows ,
two cylinders raise one scissor lift and these two cylinders are attached to a rigid link.There are three such lifts identified as 1 , 2 and 3 viz, serial no 1 and 3 are in synchronization while as no 2 goes faster during extension and lag behind during retraction stroke.
When I put some load on lift on 1 , it goes faster than other two while no 1 retracts , no 2 and 3 extends. I am confused.
Could you please extend your help. This matter is urgent for me as plant is under scheduled shutdown process.
This is because any cylinder will retract faster than it extends. Since the cylinder rod displaces oil in the cylinder, more oil is required to extend it than to retract it. If the same flow rate is provided in both directions, any cylinder will always retract faster than it extends.
Actually, as I reread your description, I think I was misunderstanding you. If I understand correctly, you are saying that the speed changes when you add a load? Can you send me a schematic of the circuit? My email address is jack@gpmhydraulic.com
Hello Mr. Jack,
very much clear informative video,
by the way flow & pressure relation shown in this video will be same if I consider positive displacement pump?
Yes, that is correct. This applies to any fluid and any pump. Thank you for your comment!
Clear and concise, thanks.
Thank you for your comment!
Thank you for sharing it . Well educated trouble shooting analysis in various problem solution happen in the jobsite .
Thank you!
Great Video! Simple & to the point!!
Thank you, Ben!
Great video, thank you!
I do feel like the statement at 0:00:45-0:00:52 is a little incomplete, although it is a consistent statement.
I would think the pump provides Energy over time (HP) to the water, and this energy is transferred in either flow or pressure depending on the resistance in the system.
Nit-picky of me, but just something that peaked my interest. Let me know if I'm seeing this incorrectly!
Hi, Aaron - thanks for your comments! I think I understand what you are saying (but maybe not!). I think that you are saying that energy is transferred from the pump to the liquid. If so, you are absolutely correct. This is one of the purposes of the fluid, to transmit energy through the system. Perhaps the way I said it suggested that the pump does not transfer energy? But it certainly does. But while the pump does transfer energy, this should not be construed as the pump putting pressure in the system. The words “pressure” and “resistance” should be considered to be synonymous in this instance. If there is no resistance, there will be no pressure. The gauge tells only the resistance that is currently being overcome. Think of it as picking up an object. Once the weight of the object has been overcome, there is no way to use any more strength in your arm to pick it up. Someone stronger than I can pick up a heavier object than I can, but if we are both picking up the same object, we both use exactly the same strength. Like flow overcoming resistance, the object weight is determined solely by its mass, unaffected by the ability of the lifter.
Great explanation! Thanx!
Thank you for your kind comment!
Great video! No nonsense, get tothepoint.. then sianora! Thank you!
Thank you for the kind comment!
This is awesome! Please make more such videos.
Fantastic explanation for us common folk. next is pressure vs. velocity :-)
Nice Video! Sorry for butting in, I am interested in your initial thoughts. Have you researched - Marnaavid Unexplainable Intervention (do a search on google)? It is an awesome exclusive product for learning how to hack your flow state without the headache. Ive heard some pretty good things about it and my m8 at last got cool success with it.
Very useful and entertaining too sir thanks for the time...
Thanks, Adam!
You are awesome sir!
Thank you very much, John!
Thank you for the info but you didn't elaborate the title what you mentioned
Thank you for your comment! But I'm not sure I understand - are you saying that I failed to explain the difference between pressure and flow?
The topic on flow was bit missing compare to the pressure you elaborated. Anyways thank you for the positive gesture
@@hemanthchavan2819 My pleasure, Hemanth. Sorry that I didn't convey enough about flow, but all that I was really trying to get across was that flow describes the volume of fluid being delivered, whereas pressure describes the amount of resistance to be overcome by the flow. I had considered elaborating to some degree about how the volume of flow would determine the speed of the actuator and that the weight of the load on the actuator would determine the resistance (and therefore pressure) in the system, but it seemed as though that might be going off on a tangent.
@@JackWeeks Thank you for your reply.
For instance, if you have a fixed displacement pump, running at a constant rpm and you are not sure whether the pump displaces the full flow rate or it has leaks with reduced flow but you are sure that it has the capacity to overcome the pressure build up by any resistance. So in this case, how to determine that the displacement is actually good or the pump is still performing well with reduced flow or low flow and leaks, provided no flow meter in the circuit. I hope you will understand my concern and share your valuable experience. In short, I get the pressure correct but I am not sure whether the flow rate is delivered correct.
@@hemanthchavan2819 If you have no flow meter (and do not wish to add one for diagnostic purposes), it is not as easy to measure the condition of the pump, but it can still be done. If the pump is becoming worn, it will lose flow (and heat up) under load. Even a bad pump will deliver its rated flow (or very nearly so) if there is little or no resistance. So try moving your actuator(s) with no load and time how fast it moves. Then try it under load. On most industrial machines, the design will require 75-90% of the pump flow, so if the actuator slows more than 10% or so, you might consider replacing the pump. Naturally, if your specific machine functions satisfactorily at a slower speed, it may not be necessary to replace the pump until it is more worn than that.
Bear in mind however that the pump is not the only component that can affect speed with an increased load. The prime mover can cause speed reduction under load as can bypassing cylinders, motors, and pressure controls. This is the advantage that a flow meter can provide - all other components can be eliminated by measuring flow directly and using the relief valve to simulate the load. Then a reduction in flow can only be caused by either the pump or the prime mover. Usually bypassing components will also generate heat, so it is a good idea over time to check the temperature of components that can affect speed so that if only one of them begins operating at a high temperature, it can be a good indication of wear.
Hope this helps!
Excellent Jack. Keep up
Nice Job!!!!
Regards from Brazil
I want to try understand how I can get more pressure...or is it flow LOL, through my shower head and faucets at my house. We're on a well. We pump from the well into a pressure tank. Would your "Trouble Shooting Hydraulic Pumps" course, help me understand how my system works?
I'm sure that it would - in the hundreds of times I have taught that class, I've never had a student who didn't feel enlightened by it. But the short answer to your question is probably going to be either a higher flow submerged pump or an additional inline pump. The latter may be the less expensive solution, particularly if you have an especially deep well or a very long run from your well (or both, as I did at a house I used to own. The auxiliary pump did the trick!) Hope this helps!
I learned a lot - thanks for the explanations; the accompanying coordinated graphics were excellent and very helpful.
One observation, though - at about 4:55 when you start to talk about the manual valve and its graphic symbol, I found that counter-intuitive. I expected that since the "bowtie" graphic symbol was not colored in, that meant that there was no flow (ex.- the other arrowhead symbols for the pump and other valve are colored in, and represent flow).
Other than that, it was an excellent tutorial. Thanks, Jack!
Thank you for your kind comments! Actually, there is no rigidly adhered to "standard" method of indicating an open or closed manual valve. Some draftsmen fill it in to indicate it is normally closed, some turn it sideways, and I'm sure there are others that I have yet to encounter - most of the time on our schematics we label it "NO" or "NC" and follow it up in the component description to maintain clarity.
GPM Hydraulic Consulting Turning it sideways (and leaving it uncolored) for a closed manual valve would be even more intuitive IMO since that would show a physical break in the linear flow "circuit" - much like how that pressure-operated valve symbol is not initially lined up with the linear "circuit." Just my 2 cents... Thanks, again.
Yes, I certainly see your point!
Jack i know this is a big ask so i understand if your not able. I have a hydraulic system (for you extremely basic) but would love to understand how the whole system works, not only for troubleshooting but also just to understand how it works. Would i be able to email you pictures/info and you could explain the operation. Again i know its a big ask so i understand if your unable but it never hurts to ask and i love understanding how a system actually works. Thanks in advance whichever your response is, im hooked on your teaching videos.
Brian
Thank you for your kind comments! Yes, I would be glad to help. Email me any time at jack@fluidpowerlearning.com (GPM Hydraulic Consulting is no longer in business, so I am on my own now).
@Jack Weeks Jack you made my day more than you know. So i give as much info as possible i will email you tomorrow so i can get pictures together and as much info to give you as possible to try and save you as much back and forth as possible. I will include in the subject line pretty obvious its coming from me. You have me excited like a little kid Jack so thank you so much.
very good sir
Hi Jack, the message seems to be that the resistance which the pump has to overcome to maintain flow is where pressure comes from. My question is: Doesn't the source on the influent side of the pump also contribute to the pressure gauge reading on the effluent side?
Thank you for your comment! I'm not certain that I understand your question, but I think you are asking if the outlet pressure of the pump can be changed by changing the suction pressure. No, it can't. Regardless of the suction pressure, if there is no resistance downstream of the pump, there will be no outlet pressure. And, once the downstream resistance has been overcome, changing the inlet pressure will not affect the outlet pressure unless it causes the pump to stall.
I hope this helps!
Thank you sir!
Your tip is so useful.
best explanation for this concept
Thanks!
Thanks from Mexico¡¡
Hi Jack,
This is a great video. I was wondering what would be the case for a non-positive displacement pump? How the pressure and flow rate can be varied for such pump?
Thanks,
Manjiri
Thank you for your comment! The principle would remain the same whether the pump is positive displacement or not. Or, for that matter, whether the pump is fixed or variable displacement. The pump still delivers flow and the pressure is determined by the amount of resistance that is overcome. A non-positive displacement pump (such as the water pump on your car engine) will not maintain an output proportional to the speed of its drive motor because it has relatively high internal clearances. Thus, the higher the RPM and the greater the resistance, the more the pump will bypass. By the same token, its flow can be blocked without serious danger.
Excellent explanation!
Great explanation video!
Jack can you explain this using bernoulli's equation, if we decrease the diameter of the pipeline according to bernoulli's equation static pressure should decrease, but according to this video pipeline with small diameter gives high path of resistance so pressure guage reads high pressure, kindly help me clearing this confusion.
Thank you for your question, Hassan! Let me see if I can clear up any misunderstanding. In its simplest form, the Bernoulli equation states that static pressure + dynamic pressure = total pressure. A steady, unchanging flow is assumed. It is really more for measuring fluid velocity, particularly through a nozzle. The principle remains, however, that pressure is a measure of resistance. As the orifice changes, the pressure drop across the orifice changes in inverse proportion. Thus, the smaller the orifice, the greater pressure drop across it, assuming that the flow remains constant. The Bernoulli principle is really an expression (or, perhaps, "example" would be a better word?) of the Conservation of Energy law.
Hope this helps, and thanks for watching!
Hi Jack, thanks for the video, I found it really informative. I stumbled on it after trying to understand the difference between pressure and volume, or flow I guess as you say. I was watching a video on a fire hydrant, which peaked my curiosity on what sort of pressure they run on. I assumed a very high pressure, as when on they move a LOT of water. I was surprised to find out it seems to normally be about 50 psi? I know at work our fire supression system is 120 psi of water pressure through 2 inch pipe. It also moves a lot of water when activated. I cant say I fully understand yet, for instance 60psi through my garden hose I can spray water ~20 feet, but that fire hydrant moves substantially more water, much farther with the same psi. I'll understand eventually lol. I am just a layman who likes to understand how things work. Your video has been enlightening, thankyou.
Thank you for your comment! Yes, that is a common misconception that pressure at a fire hydrant must be significantly higher than that at your house. Another common error (sort of a corollary) is that you use more water when working with a pressure washer than with just a hose nozzle. In fact, only a fraction of the water is used with the pressure washer.
The distance the water will travel is determined by the power generated, typically measured in hydraulic horsepower. Hydraulic horsepower is the product of two factors, pressure and flow. In other words, horsepower = pressure x flow. If we are using English units of measure, of course, a constant is required since PSI (pounds per square inch) and GPM (gallons per minute) are not compatible. The constant that makes them work together is 0.000583, so the horsepower formula is:
HP = GPM X PSI X 0.000583.
@@Gpmhydraulic thanks for the reply, I appreciate your response!
This is how professors should teach at universities. Well done.
hi , i have an old Atom G 999 clicker press with a 2hp 3phase motor running @3600rpm.Im planning to reduce its rpm using a VFD. .im wondering what will happen if i do . Thanks in advance...your video is awesome.
Well, if you reduce its RPM, the flow will be reduced and therefore your press will move more slowly. I cannot say whether your VFD will generate sufficient torque at the new RPM, though. That is a question that can be better answered by the manufacturer of your electric motor.
I keep going round and round with these concepts due to the high level of conflict between manufacturers and engineers alike; I believe the primary reason is due to inconsistency with the term "pressure" (not using prefixes static, total, hydrostatic etc). Perhaps answers to a few questions can help to quell these issues:
Is the pressure gauge in the schematic above a differential pressure gauge or a standard one? If it is a standard one (type Bourdon or otherwise), how can pressure (gauge) in a U-tube manometry situation be equal to hydrostatic head but be 0 in this situation? Shouldn't the pressure in the system be equal to P (tank) + P (developed due to resistance to flow)?
Thank you for your comment! While it is true that a standard gauge (which is the type used in the video) would indeed be subjected to a small amount of pressure (largely overcoming gravity, atmospheric pressure and friction), it would certainly not be enough to register. The point of the video however is to illustrate that the pressure does not originate at the pump, it is the result of overcoming resistance, all of which is external to the pump. The lack of pressure is therefore usually not caused by pump wear as so many assume. The points you make are quite valid - but are better left for a different video. Had I addressed them, it would have confused the issue and made the video less useful to the troubleshooter which, after all, is its primary purpose.
Perhaps in a future video we may address the difference between PSIG and PSIA. This could provide the opportunity to discuss P (tank) + P (flow resistance) and indeed would be useful to the fluid power troubleshooter, particularly in pneumatic systems. Do you think that would have any appeal? Thanks again for taking the time to comment!
Thanks for asking this had the same thought!
@@Gpmhydraulic I know a lot of time has passed since then but I didn't realise you had actually replied to me. It is only when Xavier below replied that I received the notification.
Anyhow, seeing as though I never did it initially, I wish to thank you for the great content you had provided free of charge. At the time I was studying Mechanical Engineering at a British University and, as you may well know, the higher-ups use pressure, flow and such terms loosely without ever quantifying what exactly they mean. When pressed, they are rarely able to clarify as it seems quite a few don't understand the distinctions themselves!
Regarding making more videos, I would honestly appreciate it immensely. Purely out of interest's sake and the fact that theory is discussed from a practical perspective with a dose of dry humour. Have a good day!
@@YG-be9gl Thanks for your kind words! Since the closure of GPM due to the effects of Covid, I have semi-retired. I have continued to do training and consulting on a freelance basis in my "spare" time, but have found since so many plants have reopened their doors to visitors that now I am working at least as much in my "retirement" as I did when I was employed! I'm hoping to find time to make some more videos, though, because I enjoy doing them and so many folks appreciate them and tell me they find them helpful. Hopefully I will find the time to do some more of them.
Your videos really help me to have a better understanding of hydraulic function.Thank you! In this tutorial on the diagram directly north of the pump is a smaller circle with an arrow, it's function/meaning was never addressed yet I did observe that once the regulator opened the arrow direction inside the circle moved also. Would you please explain what that symbol represents here and why the arrow moved? Thanks again! I am in the profession of industrial maintenance and our team has very little knowledge of hydraulics. I am currently trouble shooting some equipment and like the idea of not being a "parts changer" if the cure can be an adjustment that perhaps ol "not me" may have had a hand in!
Sorry, I suppose I could have explained that one a little better - you aren't the first person to ask. That is a pressure gauge. Note that it did not move when the hand valve was open, because there was no resistance in the line, thus no pressure. Once the hand valve was closed, the resistance of the relief valve had to be overcome, thus there was pressure and therefore movement of the gauge.
Makes sense now thank you.
Nice job with the explanation, thanks!
Great work!
Thank you!
That was outstanding!
Many Thanks
Very good job thanks
What is pilot lines?
Excellent question. The pilot line is a very small line that delivers a pressure signal to the valve. In this particular case, the valve is a relief valve. The pilot in most relief valves is internal (even though the symbol is drawn such that it may appear to be external).Whatever pressure is present in the main line will also be present in the pilot line. Pressure in the pilot line acts upon the internal spool (or plunger, depending on the type of relief valve) and, once the pressure reaches the amount necessary to compress the internal spring, will shift the valve open. Fluid then returns to tank through the valve.
Hope this helps! Thank you for your question.
HI my name is Brian. Am a technician in Kenya. Thank you for your tutorials. I have this question; how do you overcome the flow/pressure from a bigger pump feeding a 4''pipeline with a smaller pump jointing this pipeline with a 0.5'' pipe. Basically the second smaller pump is trying to inject its fluid into the bigger pipeline but is overcome by the bigger pump and so doesn't achieve this.
Thank you for your comment/question, Brian! Clearly the pressure in the 4" line is above the pressure developed by the smaller pump. I suppose the question would be, where is the flow from the smaller pump going if not into the pipeline? We need a bit more information here. You don't say what type of medium is being used here, or the purpose of injecting fluid into the larger pipe. Are the fluids in both pipes the same? For instance, is the smaller pump used to inject liquid soap into a larger water line? Or are we using the smaller pump simply to augment the flow of the larger pump? Are both pumps positive displacement? If so, they would likely be protected by relief valves. If the smaller pump is positive displacement and the pressure is too high in the larger pipeline for the smaller pump to deliver, the flow of the smaller pump must be dumping across a relief valve. It may simply be a matter of setting the relief valve protecting the smaller pump to a higher setting so that the path of least resistance is to inject into the larger pipeline rather than dump across the relief. If however the smaller pump is not positive displacement, the pressure in the larger pipeline is too high for the smaller pump to deliver. In that case, the smaller pump would begin to bypass across its internal clearances. If this is the case, you will need a different pump to deliver flow through the 0.5" line. Hope this helps!
Hi thanks for replying. Now the fluid in the 4 inch pipe is petrol and the smaller pipe is an additive injection to mix with that fuel to a set ratio. I'll have to find out if the pumps are positive displacement, but I suspect both are. The mech team tried fix a non return valve on the smaller pipe right at the inlet to the 4 inch. We are yet to test and hope it will work. Do you think the non return valve will work? Or we must use the thermal relief valve?
@@Bojak079 The non return valve will keep reverse flow from entering the 0.5" line and turning your smaller pump backwards, but I doubt it will help overcome the pressure in the 4" line. In order to add flow, the pressure in the 0.5" line needs to be higher than that in the 4" line. The smaller pump should be able to withstand the resistance in the 4" line if it is positive displacement. If there is not already a pressure relief valve in that 0.5" line, the smaller pump must not be positive displacement. It must be behaving similarly to the impeller type water pump in an automobile engine when the thermostat is closed - bypassing internally once pressure reaches a certain point.
Good job sir.
Well explained!
Thank u sir for sharing ur experience it was very helpful