Equal % valves - Part 2 - Why do we use them?

Рет қаралды 10,316

3 жыл бұрын

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/d/1BjVYIWrgT4Ea4WMUjTCoFNzk3fAUSZvDRp4Tk_RFJKc/edit?usp=sharing
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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#ProcesswithPat

Пікірлер: 38

@xse345 3 жыл бұрын

Nice, I only had a vague Idea about this topic. Thanks for the wonderful explanation.

@ProcesswithPat 3 жыл бұрын

Thanks AJ! Yes I’ve also only had a basic understanding of it, but doing it made it easier to appreciate.

@danishiqbal3838 2 жыл бұрын

I am shoked to see just few hudred views over this tremendous video!!! literelly I havent seen any better explaination anywhere

@ProcesswithPat 2 жыл бұрын

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.

@arvydaslatvenas8781 Жыл бұрын

Nice to have it premiered on my birthday 07/19. Feels like a great present for an engineer :)

@patrickgijbels7985 Жыл бұрын

Great explanation, I showed this to my students to help them understand this topic. Nice job !

@TheHinaiibrahim 2 жыл бұрын

Excellent way in explaining the concept. Thanks for making this video.

@mikefochtman7164 10 ай бұрын

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.

@acopp6891 3 жыл бұрын

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

@ProcesswithPat 2 жыл бұрын

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.

@CharleyGR 11 ай бұрын

Awesome video. Thanks for sharing this

@Ryarios 11 ай бұрын

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.

@naturalnewbie98 2 жыл бұрын

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.

@ProcesswithPat 2 жыл бұрын

Cheers man, thanks! Hope it’s useful!

@mostaphanaghibi480 Жыл бұрын

Thank you very much for this great and useful video.

@vtbhanukiran1231 Жыл бұрын

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.

@ProcesswithPat Жыл бұрын

You are most welcome! Glad it helps.

@khidrie1 2 жыл бұрын

Great video, thank you. I finally understood why we use equal percentage not linear 😁

@abilashjohn1532 11 ай бұрын

Nice ,,such a great explanation about this topic,,,,thanks

@ThePriyankanair Жыл бұрын

Wow so nicely explained 👍

@garymok1839 2 жыл бұрын

You are awesome! Thanks for sharing.

@pedrochirivella2473 2 жыл бұрын

Thanks for creating this video with a such a great content. 👍🏻 I have subscribed to your channel. Keep it up 🙂

@affanbhaijaan65 3 жыл бұрын

Informative

@abdessamedghettas7167 2 жыл бұрын

Many thanks great videos

@brahimizohir4411 Жыл бұрын

Gréât explantation thank you sow mutche

@israelmoya7702 3 ай бұрын

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?

@ali200800500 2 жыл бұрын

good video thanks

@ProcesswithPat 2 жыл бұрын

Thanks a lot! I was quite pleased with how this one turned out.

@panoskb9405 Ай бұрын

Hi Pat, in the formula of Cv value, where the number 27,3 comes?

@JasonMitchellofcompsci 6 ай бұрын

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.

@ahmedabdulamir6190 Жыл бұрын

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 :)