Equal % valves - Part 2 - Why do we use them?
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- Опубліковано 10 лип 2024
- Why would you ever use an equal percentage valve characteristic instead of a linear one?
Link to the sheet I use to generate the curves:
docs.google.com/spreadsheets/...
00:00 Intro
00:36 Quick overview of Cv and characteristics
02:14 Responses in control systems
04:28 Linear valve response on 2 km pipeline
07:13 Installed & inherent characteristics
08:53 Equal percentage valve response on 2 km pipeline
10:43 Summary & rule of thumb
11:46 Keep this in mind
Process with Pat is the place to come for perspective and to ask stupid questions. I want you to leave more knowledgeable, confident, motivated, and most importantly, curious. I also want to invigorate a field that seems tired and uninspiring, at least if you get your perspective from internet forums. These are not lectures. This is a place for you to leave thinking “Oh! That’s why...”
This channel is not only for chemical engineers - anyone who works with processes should be able to find something of value here.
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Nice, I only had a vague Idea about this topic. Thanks for the wonderful explanation.
Thanks AJ! Yes I’ve also only had a basic understanding of it, but doing it made it easier to appreciate.
I am shoked to see just few hudred views over this tremendous video!!! literelly I havent seen any better explaination anywhere
Hahaha thanks. Yeah, it’s one that I’m probably most proud of, and I was learning as I made it.
I think it’s probably a little niche. But the point is I’m not chasing views, if there are a handful of people that really benefit then I’ve achieved what I wanted to achieve!
Thanks for the nice comment.
Nice to have it premiered on my birthday 07/19. Feels like a great present for an engineer :)
Excellent way in explaining the concept. Thanks for making this video.
Great explanation, I showed this to my students to help them understand this topic. Nice job !
Great discussion about control valve characteristics. I'd worked with several control systems and getting the linear behavior was always a key part of getting good control performance. One notable problem was a control valve to regulate steam flow to an auxilliary turbine that was coupled to a centrifugal pump where the end goal was to control the flow via pump speed. So first the system curve, then the pump curve, then the hp vs pump speed, then steam flow vs turbine power developed, then finally steam flow vs valve percent opening. Ugh... So naturally, we did some manual tests at various points, plotted things out and made a 'little black box' of electronics that converted linear flow controller output to the desired valve-open command.
Process flow control systems have always been fascinating for me, and I've enjoyed your videos on the topic. Thanks you.
Awesome video. Thanks for sharing this
I remember studying this particular topic during my chemical engineering course and I didn't get very much of it. This was very well explained and understandable
Yes, I certainly had the same experience. It is something that is fairly easily demonstrated and hopefully sticks, rather than needing someone to memorise it and parrot it later (which I was doing before going through this exercise). Thanks for the comment.
Thanks for creating this video with a such a great content. 👍🏻
I have subscribed to your channel.
Keep it up 🙂
Thank you very much for this great and useful video.
You are a gentleman and scholar! Excellent explanation. I love workbooks like this, I have added your workbook to my toolbox. greetings from a test engineer.
Cheers man, thanks! Hope it’s useful!
Great video, thank you. I finally understood why we use equal percentage not linear 😁
Nice ,,such a great explanation about this topic,,,,thanks
One other thing to keep in mind is that Eq% works better when you have a normal flow close to the low end of the valve. For instance, say you normally need 2 gpm of flow through a valve, but there are times you want 10 gpm lose when you want to quickly fill a tank but after doing so, you need much less flow to maintain that level. The Eq% gives you better resolution and finer control at the lower flow while allowing you to still have high flow when you need it. The quick opening trim can give you better resolution and finer control when your normal flow requirements are close to your maximum flow rate.
Wow so nicely explained 👍
Great explanation.
I am a Quality GM with Doosan, and i am able to understand Control Valve design.
Thank you very much for your explanation and hard work.
You are most welcome! Glad it helps.
You are awesome! Thanks for sharing.
Informative
Many thanks great videos
Gréât explantation thank you sow mutche
Pats, how would you go from a % opening vs CV plot to a % opening to a flow rate plot. That is the part that confuses me. Also would the CV only work for one specific pressure drop?
Hi Pat, in the formula of Cv value, where the number 27,3 comes?
good video thanks
Thanks a lot! I was quite pleased with how this one turned out.
Nice. A question. You said that some of the valves had higher operating cost. But if we are hitting the same targeted flow of 30 with all else being the same in the system, then we have the same delta-P across the valve to achieve it. Isn't the pressure capacity of the pump vs the chosen operating pressure what selects for cost? Though I never studied chemical engineering and I'm a college drop out so I may have it wrong.
Omg it's great
How did you calculate the value of 0,7 when you choose 25% ▲p of the total pressure drop i didnt get that? could you please explain that or some one :)
Brilliant. Nice, clear explanation. Excellent graphical representation. The background "music" almost drove me out.
Thanks a lot! And thanks for the feedback. Too loud, or style? Or both?
@@ProcesswithPat Repetitive?
Appreciate it!
The title is so sexy XD
Shoulda tried harder, huh?