Jump to content



Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

Vertical Tank Selection

New Blog Entry

Low Flow in Pipes- posted in Ankur's blog

0

Capacity Of Control Valve When 100%opening

control valve

2 replies to this topic
Share this topic:
| More

#1 Sapao

Sapao

    Veteran Member

  • Members
  • 37 posts

Posted 13 August 2017 - 09:27 AM

Dear all 

 

I would like to consult you about the control valve.

 

My control valve was design at below condition

 

Flow rate(m3/h)                        :  max. = 79.1, Nor. = 79.1, Min. 37.2

Inlet press.(kg/cm2g)               :   max. = 61.9, Nor. = 61.9, Min. -

Diff press.(kg/cm2)                   :   max. = 2.8, Nor. = 2.8, Min. -

Temp(degC)                             :   max. = 320, Nor. = 312, Min. 300

Cal. CV                                    :   max. = 45.74, Nor. = 45.74, Min. 21.50

Rated CV                                 :   165

 

 

How can I calculate when control valve open 100%op?

 

Best regards,

Salapao.

 



#2 Saml

Saml

    Gold Member

  • Members
  • 287 posts

Posted 13 August 2017 - 07:35 PM

You have to solve the flow for a Cv of 165.



#3 vjmromero

vjmromero

    Brand New Member

  • Members
  • 9 posts

Posted 14 August 2017 - 09:12 PM

First, you need to establish how much is the available head i.e. pressure at pump discharge (or source pressure). Say pressure is 80 kg/cm2,

 

we can assume that flow is turbulent, and only hydraulic circuit has dP only due to PIPING and control valve.

 

Then, dP of line is proportional to Q^1.9.

 

Total Total P = Destination P + dP line + dPvalve ;  dPline = TotalP-Destination P - dPvalve

 

(80-59.1-dPvalve) / (80-59.1-2.8) = (Qmax/79.1)^1.9    --- eqn 1.

 

For control valves, Q is proportional to Cv*sqrt(dPvalve)

Then,

 

Qmax/79.1 = 165/45.74 sqrt (dPvalve/2.8)

 

so, Qmax=285.341 (dPvalve/2.8)^0.5   -- eqn 2.

 

Solving simultaneously, Qmax=84.75 m3/h... (assumption source P at pump discharge = 80 kg/cm2; same condition applies i.e. liquid level or static head at source and destination are the same for all cases)






Similar Topics