This is the best description I've heard to explain how pumps operate under it's load. It took me a while, but once I figured it out for myself, everything just became so much easier and highlighted the importance of knowing the system curve when selecting a pump, instead of just providing a single duty point
Fascinating content! You're a great teacher, Pat. It's a lost art to be able to explain concepts thoroughly and clearly, and with a bit of humour in the process.
The flow and pressure are the result of some amount flow overcoming whatever the the applied resistance is at the time. The pump only expends the minimum amount of energy required to get whatever flow it can through that resistance, determined by how efficiently the pump can convert its impeller's rotary motion into forward motion of a fluid at any given flow rate through it.
bro i stopped the video to like it and subscribe and it hit me ...... you only have 900 subscribers??!!!!!!!!! , dude you are high end RU-vidr. you really are going in the right direction and I believe your channel is getting a lot bigger soon enough. good luck and keep the effort please..... awesome man truly great
That’s really kind, thanks a lot man! Am not worried about the numbers… If the stuff is good enough it will come! I always say that as long as I answer a question that only a handful of people have then that’s why I started and I’m happy! Once again, thank you.
Yes, Pat should have more FLOW based on his content. BUT wait... Seems like the flow has increased dramatically recently . Does this mean he has no HEAD? 😂
Nice work...........'Bro'. Very few people have the gift of taking something complicated and being able to anecdotally explain it in more digestible terms. You'll be Professor Pat before you know it.......'Bro' 😂😂 Bonus points for the SaFa accent.
This is perfect. Use your common sense and intuition before memorizing equations without any real understanding of how things work. I was thinking about these types of things when I started learning about all of this.. A week ago... And this video just drives home the point.
I am working in automotive manufacturing and I can translate this video like this: Always check your inputs and outputs first, then f*ck around your machines. SiSo flow. Shit in Shit out. With a pump I would check frist for moisture, bubbles, temperature, viscosity going in, and only after that would examining the HW. 6 out of 10 the raw material is the root cause not the machine.
You are presupposing synchronous motors there. The motor might be, or might not be - in which case everything you said would no longer hold true... which is the reason why we have pump-curves. And if the pressure is too low - that can have so many causes, and yes multiple of those could be related to faults with the pump or motor. The motor might be running at only 2 phases instead of 3, or the pumpt might have bad lubrication, or the piping is leaking, or anything else.
You are nitpicking how people often speak. The pump control systems are being treated as if they were integral to the pump. Maybe the vfd is operating at a different frequency because a lower flow is desired today. Maybe a higher than expected demand is occurring and the pump speed was not adjusted to account for this. The question is based on appearances but still leads towards steps to rectify the situation. Also, you cannot just slap a bigger pump in place. A bigger pump often requires bigger pipes. Determining the proper solution requires a proper analysis of the situation.
@5:50 you say the pump would give 0 pressure when there's no load. Can you clarify which pressure you're talking about? I assume you mean 0 (ie. atmospheric) static pressure? There would still be dynamic pressure due to the kinetic energy of the moving water?
That’s fantastic to hear AJ. I have actually been keeping them this duration on purpose thinking that I must get to the point and have a message without it turning into a lecture. I want to avoid technical overload, especially if the intention is to help younger engineers. But it’s awesome to hear longer videos aren’t unwelcome! Thanks for the feedback.
Very well explained. This was the first time I had this explained as you did. I will have to watch again, but it is helping me for sure. Peaceful days to you
Which other videos do you recommend, specifically related to pumps but explained from an intuitive perspeive like this video.? I don't see any playlists on this topic.
One should also understand the concept of total system pressure is the sum of local static and dynamic pressure plus global pressure. Trying to run a pump against a valve with minimum openings and maximum should also give one a intuitive understanding of the head and system curves.
Excellent stuff. I think the same thing applies to fans. I know we're dealing with a compressible fluid here but, I think, the same thing applies. As I recall, mathematically, a system is described by a positive curve/slope. A pump or fan has a negative curve. When one is superimposed on the other they naturally cross - at least in the real world. This is the operating point. The system curve changes if filters/strainers get choked up or if dampers/valves get opened or closed. And the fan/pump curve changes if the device is speeded up or is slowed down. The net, end result is - where they cross, is the operating point.
Incredible video!! Does throttling the discharge valve make it easier for the pump then?? Because it reduces the load (flow) it produces at the same rpm?
Hello Pat, in order to help myself understand the message in this video better, I have a hypothetical question to ask you: Let's say there is a reservoir with its bottom at sea level filled up to 250 feet. Water leaves near the bottom of this reservoir through a dam spillway, and travels through many miles of straight, large pipe. The water eventually reaches a pump station where the pipe becomes the influent for a large pump. The job of this pump is to send the water through a stretch of no slope pipe until it reaches the base of a hill, at which point the pipe inclines and water makes its way into the bottom of a 30 ft tank sitting at the top of that hill. Initially this tank on the hill is totally empty, and the pump station has no water running through it. At this moment, the pressure gauge on the influent side of the pump as well as the pressure gauge on the effluent side of the pump both read 0 psi. Then the reservoir's dam spillway is opened and the water begins its journey through the miles of pipe, eventually reaching the pump station. As the water first travels through the pump influent, the pressure gauge on the influent side of the pump reads 50 psi (I don't know what a logical psi value would be here for the reservoir level). The pump is running now, and water is exiting the pump effluent. Water is now flowing into and out of the pump, but no water has reached the base of the hill where the pipe first inclines YET. The water is still just making its way towards the hill through the section of pipe that has no slope. At this moment, *what would the pressure gauge on the effluent side of the pump read?* My guess is 50 psi same as the pump influent gauge because there is pressure from the reservoir head, but no load/resistance on the effluent side yet. This was more of an essay or story than a question, maybe the question was flawed and doesn't even make sense. Hopefully the concept I'm trying to get at that I'm still wrapping my head around is clear. I'm kind of asking a question when I don't really know what my question is, hence the long comment. Thank very much for reading!
Hey there! There’s quite a bit in your not-really-question, but it’s pretty interesting! First and foremost - you have defined some heights (you didn’t mention how high your hill was) but no flow rate requirements or line sizes. You would need line dimensions/geometry as well as the flow rate to be able to say anything about the pressure. So the 50 psi guess you gave - it totally possible - you could design the pipe so that at the design flow rate the discharge pressure is 50 psi (as long as this is enough to get uphill). So we can’t be too specific with values because the problem isn’t defined enough. Secondly, you have 250 ft in the reservoir which means you can flow to the tank without a pump as long as your hill is less than 220 ft (250 reservoir minus 30 tank). The RATE would depend on your line size. Need more flow? You need a bigger pipe. The main reason you’d have a pump is if the flow rate required would need really large pipes for low pressure drop, and so it becomes more economical to install a smaller pipeline and overcome the pressure drop (due to higher velocities is a smaller pipe) with a pump. Thirdly - your question - what is the pressure as the fluid reaches the pump? You are describing a transient state and so the pressure will increase the more the discharge line fills, and yes, it will increase even quicker when the fluid starts flowing uphill. But the pressure will start increasing even before the liquid reaches the uphill. Imagine you have a water/air interface. Air flowing through a pipe also has pressure drop. So your pump pushing that air-water interface along the pipe is not only causing water flow, but also air flow. Both of these have their own pressure drop in the pipe. It’s just that air flowing at the same velocity as water in the same pipe causes less pressure drop because of the very low air density. So even before you’ve reached the uphill the proportion of pipe exposed to water versus pipe exposed to air is increasing, and the water experiences higher pressure drop, resulting in an increase in discharge pressure from the pump. If your pump was running at constant speed that would mean the flow would be dropping over time. Once again - the significance of all these effects is totally academic because we have no idea what the line sizes and velocities are. Finally - practically speaking - you need to ask yourself when you would start the pump. Realistically you’d open a valve on the reservoir and one on the tank and flood the line/pump. It’s not likely that you time the pump to start as it sees liquid. It is interesting to consider how the pump discharge pressure changes theoretically though. However, you would have valves on the discharge of that pump and you would never start the pump with that discharge valve open. That is because a motor draws an extremely high current when it starts because it takes force (and electrical current) to accelerate it to speed. If your valve is open then that entire flooded line is placing load on your pump/motor which will push the starting current up even further. You would have over-current protection (basically a circuit breaker like at your house) on your pump motor to protect it from burning out due to high electrical current. Does that help?
@@ProcesswithPat Thanks Pat, I guess what I'm wondering is this: Do pump effluent pressure gauge readings equal just the amount of pressure/resistance on the effluent side of the pump, or do they equal that plus the pressure on the inlet side of the pump? If my inlet pressure was 50 psi and I had no resistance to flow on the outlet, would the outlet pressure be 0 psi or 50 psi?
If the ONLY thing you do is increase suction pressure to a centrifugal pump, then the discharge pressure and flow will both increase, but the DIFFERENTIAL pressure will drop. So if you start with suction at 0 psi and discharge at 50 psi, and then you increase the suction to 50 psi, then the discharge will got to some thing like 90 psi. However it is also totally possible to increase the suction pressure from 0 to 50 and maintain the same differential to gave 100 psi discharge. The best way to understand is by looking at pump/system curves. I’d be more than happy to do a video on it, if it’d be useful?
Hey Manoj? You looking for something specific? I like to put in a bit of work into it, but I need a good understanding to explain it clearly, and although I understand compressor surge, anti surge not something I use daily… so I don’t want to pretend to know thing I don’t!
@@ProcesswithPat if possible can you do a video about centrifugal compressor surge and the anti surge devices used on the centrifugal compressor to avoid the surge phenomenon
