From Cameron, former BYU student, who is now working at Chevron: "I wanted to give you some feedback on your valve design video. I loved it. I remember struggling a lot with the valve design equation. Having watched the video I feel the students will grasp it better this time around. Well done! Also, to provide some real world relevance to the video, I recently was tasked with verifying some P&IDs within a plant at our refinery here in El Segundo. The overall purpose was to improve documentation, but it was also a huge learning experience for me. My knowledge of valves was definitely lacking, so I spent some time with a more experienced contractor who has worked for decades in refineries and walked through a plant and just picked his brain. If the students can come out of school knowing both what each valve type looks like on the inside but also on the outside, they will be better prepared than I was!" Thanks, Cameron
Hi, I m writing from Venezuela, I have this question related to the equation term f(l)...that you mention its a lift function, but its not clear at all for me what does mean...?, beside I understand that the word "lift" means put up something thus, if is so, I can literally understand it means the slope of the characteristic curve of the valve, am I right?, so actually the term f(l) just means the type of valve...e.g. lineal valve or percentage valve...please light me about it
+Carlos Ivan Hernandez Sanchez yes, you have the correct idea. It is a relationship between lift (such as 20%, 50%, 90% open) and flow through the valve. It is just an empirical correlation to describe the different valve trims.
John, your video simply pops up when I did a search on control valve. It is a great video. Although working in the chemical industry for over 18 years, I am not exactly sure the difference between different control valves. It is great to learn from your video. Thanks!
I'm glad that you found the video useful. Sometimes it's helpful to see the cutaway diagram of the valve. Globe valves are the most common for process control applications.
Very excellent videos about valve type selection regarding real life engineering work. Thanks for sharing. Can you have it in a real valve calculation example for a project.
Yes, the valve equation with the different trim types can be used in flow loop design. Here are design problems for practice: apmonitor.com/pdc/index.php/Main/FlowValves
John, great video! I have a question. Why it is important for the installed control valve characteristic to be linear. I understand that it will improve the control performance, but how?
If the system is linear then a PID controller will work equally well in all ranges of operation. If it is highly nonlinear then the controller will be sluggish at high flows and unstable (oscillate) at low flows.
For globe valves It is also important to know the mechanical design of seat and plug to find out if a valve is air to open or air to close.you can not say that a globe valve is air to open/close only by looking to the actuator.
hello and thanks for the video i just want to montiend that you can't just know if the valve is Fail-Open or Fail-close from the actuator only you need to know also if the valve is direct or revers acting
Thanks for your comment. You are correct that it can be challenging with some valves to know whether they are fail-open, fail-closed from the exterior. I should have mentioned that some valves also fail in the current position and don't move to 100% open or 0% open when they lose power or pressure.
hii, i have a doubt on your step 4 of valve design flow chart, the flow chart says ∆P system variation against flow while emerson's fisher guideline says ∆P valve(drop across valve) , pls clarify
Both are correct. The Emerson Fisher guideline is referring to characterization of the valve in terms of lift versus flow while the flowchart helps you decide which type of valve to select. If there is a lot of system dependent pressure drop (there usually is) then an equal percentage valve is best. Equal percentage valves are the most commonly installed type of valve trim.
Hii This video is really helpful to understand the valve design. i was wondering if you could explain the complete data sheet components in your next video. And i have two questions. first is, how to define rangebility of a control valve? and second is, most often i see Cv written in a control valve data sheet. Is this Cv related to 100% open condition or what? because Cv changes with the opening of control valve. so i am confused. i hope you understand my problem. Waiting for your reply.
The Cv value is related to valve size and is used in the valve design equation as shown here: apmonitor.com/pdc/index.php/Main/FlowValves Unfortunately, I don't have additional information on the data sheets.
Typically the datasheet will have a max cv stated (100% open) and a lot of times it will state the cv at the designed flow. typically it doesn't give you the full picture
The valve design equation is at 9:18 in the video. The pressure drop is on the right hand side of the equation so you'll need to rearrange it to solve for Delta Pressure.
APMonitor.com got it but, looking at the logic diagram point 2, it has to be calculated as one of the first steps in there process of sizing the valve so I cannot understand. I just know the maximum flow rate I want to have in my pipe and the fluid.
+bbdavallonga, the pressure is typically available from a pump or height difference of the upstream fluid. The pressure drop is all of that pressure if the valve is closed. If the valve is open then it is determined by the Cv (valve sizing). There is additional information on valve sizing and pressure drop calculations here: apmonitor.com/pdc/index.php/Main/FlowValves
From Cameron, former BYU student, who is now working at Chevron:
"I wanted to give you some feedback on your valve design video. I loved it. I remember struggling a lot with the valve design equation. Having watched the video I feel the students will grasp it better this time around. Well done! Also, to provide some real world relevance to the video, I recently was tasked with verifying some P&IDs within a plant at our refinery here in El Segundo. The overall purpose was to improve documentation, but it was also a huge learning experience for me. My knowledge of valves was definitely lacking, so I spent some time with a more experienced contractor who has worked for decades in refineries and walked through a plant and just picked his brain. If the students can come out of school knowing both what each valve type looks like on the inside but also on the outside, they will be better prepared than I was!"
Thanks, Cameron
Hi, I m writing from Venezuela, I have this question related to the equation term f(l)...that you mention its a lift function, but its not clear at all for me what does mean...?, beside I understand that the word "lift" means put up something thus, if is so, I can literally understand it means the slope of the characteristic curve of the valve, am I right?, so actually the term f(l) just means the type of valve...e.g. lineal valve or percentage valve...please light me about it
+Carlos Ivan Hernandez Sanchez yes, you have the correct idea. It is a relationship between lift (such as 20%, 50%, 90% open) and flow through the valve. It is just an empirical correlation to describe the different valve trims.
John, your video simply pops up when I did a search on control valve. It is a great video. Although working in the chemical industry for over 18 years, I am not exactly sure the difference between different control valves. It is great to learn from your video. Thanks!
I'm glad that you found the video useful. Sometimes it's helpful to see the cutaway diagram of the valve. Globe valves are the most common for process control applications.
Excellent, Today I saw your useful video. Thanks for good illustration.
very nicely explained! thanks!
very good explanation!!
Very excellent videos about valve type selection regarding real life engineering work. Thanks for sharing.
Can you have it in a real valve calculation example for a project.
Yes, the valve equation with the different trim types can be used in flow loop design. Here are design problems for practice: apmonitor.com/pdc/index.php/Main/FlowValves
John, great video! I have a question. Why it is important for the installed control valve characteristic to be linear. I understand that it will improve the control performance, but how?
If the system is linear then a PID controller will work equally well in all ranges of operation. If it is highly nonlinear then the controller will be sluggish at high flows and unstable (oscillate) at low flows.
So helpful. Thanks
Thank you, I'm working in Flowserve Saudi Arabia.
+Husam Kifaya Flowserve offices are near Provo in Springville. I've been to KSA 5 times for about 1 month each time. Have you been to al-Jubail?
Thanks for sharing
Awesome
Nice Video
For globe valves It is also important to know the mechanical design of seat and plug to find out if a valve is air to open or air to close.you can not say that a globe valve is air to open/close only by looking to the actuator.
+ali moshiri Thank you for that important contribution.
hello and thanks for the video
i just want to montiend that you can't just know if the valve is Fail-Open or Fail-close from the actuator only you need to know also if the valve is direct or revers acting
Thanks for your comment. You are correct that it can be challenging with some valves to know whether they are fail-open, fail-closed from the exterior. I should have mentioned that some valves also fail in the current position and don't move to 100% open or 0% open when they lose power or pressure.
hii, i have a doubt on your step 4 of valve design flow chart, the flow chart says ∆P system variation against flow while emerson's fisher guideline says ∆P valve(drop across valve) , pls clarify
Both are correct. The Emerson Fisher guideline is referring to characterization of the valve in terms of lift versus flow while the flowchart helps you decide which type of valve to select. If there is a lot of system dependent pressure drop (there usually is) then an equal percentage valve is best. Equal percentage valves are the most commonly installed type of valve trim.
Hii
This video is really helpful to understand the valve design. i was wondering if you could explain the complete data sheet components in your next video.
And i have two questions. first is, how to define rangebility of a control valve? and second is, most often i see Cv written in a control valve data sheet. Is this Cv related to 100% open condition or what? because Cv changes with the opening of control valve. so i am confused. i hope you understand my problem. Waiting for your reply.
The Cv value is related to valve size and is used in the valve design equation as shown here: apmonitor.com/pdc/index.php/Main/FlowValves Unfortunately, I don't have additional information on the data sheets.
Typically the datasheet will have a max cv stated (100% open) and a lot of times it will state the cv at the designed flow. typically it doesn't give you the full picture
hi all. how can i calculate the pressure drop through the valve?
The valve design equation is at 9:18 in the video. The pressure drop is on the right hand side of the equation so you'll need to rearrange it to solve for Delta Pressure.
APMonitor.com got it but, looking at the logic diagram point 2, it has to be calculated as one of the first steps in there process of sizing the valve so I cannot understand. I just know the maximum flow rate I want to have in my pipe and the fluid.
+bbdavallonga, the pressure is typically available from a pump or height difference of the upstream fluid. The pressure drop is all of that pressure if the valve is closed. If the valve is open then it is determined by the Cv (valve sizing). There is additional information on valve sizing and pressure drop calculations here: apmonitor.com/pdc/index.php/Main/FlowValves
thank you very much