Regarding the calculation and selection of regulating valves
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This post was last edited by A Entropy on 2021-12-27 08:38 My process is roughly like this. If we want to purchase a regulating valve for our project, the instrumentation personnel need to issue a specification book first. The specification book contains the three values of the CV value, opening and selected CV value of the regulating valve. I read the specification sheet of the regulating valve issued by the previous design institute, and then learned it myself.* I checked the calculations of the regulating valve online and compared them with the specifications of the design institute. The following two pictures are the calculations I found online, one is more than 80, and the other is 0.22. There is a huge difference between the two values. I would like to ask what is going on. Are these two values the same thing? The design institute's specifications are very close to the value of more than 80. Does the KV value of 0.22 have any other effects? Another question is, after calculating the CV value and opening, how to choose the size of the valve DN40 or DN50?
The pressure difference unit in your second picture is obviously wrong. 0.05mpa is 0.5bar. According to that formula, the kv value is 70.36. Multiply it by 1.167 to convert it to cv, which is 82.1.
To calculate the cv value, first select the caliber and then the opening. Once the caliber is determined, the rated cv is also available. Then based on the relationship between the calculated cv and the rated cv, calculate the opening and ensure that the opening is around 60-70%.
Differential pressure value is wrong； For questions about DN40? DN50?, find out the rated cv or rated kv, and check whether the opening is appropriate based on the calculated cv or kv.
Thank you, sir. It’s true that the unit is wrong.
I searched and found that there is also a multiplication of 1.156 times. I want to know which one is correct. The calculation of 1.156 times is 81.33
Could you please share a software or website?
These are all websites of valve manufacturers. Will they be said to be advertisements when posted, so they are not posted.
Is it okay to send a private message? :), I have always doubted whether the excel I made is wrong, and I feel unsure every time.
1MPa=10bar. The poster in the second picture wrote 50,000 bar, which is 5000MPa.