1 reply to this topic

[CHEMSTRONG]

Hi All,

 

Background :

 

Generally in process dynamic simulation, control valve Cv is taken based on datasheet details.. It is taken for max flow which occures at generally 50-75 % of valve opening..It varies from valve to valve.. But most of the time, valve datasheets are not available.. Most of the dynamic simulation companies follow certain Cv valve sizing charts like line size vs Cv value in absence of valve Cv datasheets..and if this Cv is not giving 50-75 % opening at steady state, then it is tuned to get that opening of valve at steady state conditions.

 

My question is

 

In Cv chart, Cv is given in US units(gallons/ Psi ) or Metric units as Kv.. But if my H & MB data  w r t inlet pressure-outlet pressure and flows are in different units than that of this Cv chart, then will it be ok to use this chart? Request guidance from members..How this Cv in different units will hold good for diff H & MB conditions?

Is there any standard for Cv units?

 

Cheers

[MTumack]

C_v is expressed as GPM of Water of flow per 1 psid drop across a valve. I believe at 60° Fahrenheit.... but dont quote me. Might be 50 or something.

 

K_v is m³ / 1 bard.

 

I believe conversion between the two is as follows: C_v = 1.16 K_v  

 

That being said, If I were you I'd just call the valve manufacturer of your choice and get a PDF bulletin that provides all the values you want in whatever measure.

 

EDIT: See the following, on P. 120

 

http://www.documenta.../book/cvh99.pdf

 

K_v = 0.865 C_v

 

I'd use these values, citable and is less rounded.

Edited by MTumack, 15 January 2015 - 03:06 PM.