Cv correlation between gas and fluid?
Cv correlation between gas and fluid?
(OP)
If I have a valve with a known Cv for fluids (water specifically), is there a correlation that can be made to the Cv for gases (specifically CO2)?
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Cv correlation between gas and fluid?
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Cv correlation between gas and fluid?Cv correlation between gas and fluid?(OP)
If I have a valve with a known Cv for fluids (water specifically), is there a correlation that can be made to the Cv for gases (specifically CO2)?
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RE: Cv correlation between gas and fluid?
RE: Cv correlation between gas and fluid?
You can transform this into a dimensionless K value if you like - this can be used for all gasses and liquids alike.
Best regards
Morten
RE: Cv correlation between gas and fluid?
Is that to say that I just need to convert the units of my water-based Cv to the flow units I want for CO2? Basically GPM to CFM?
RE: Cv correlation between gas and fluid?
Check your valve vendor catalogs, they will have the sizing equations in there. You can, depending on your pressure and temperature, use an ideal gas sizing equation or a real gas sizing equation (the latter if compressibility effects are significant].
A valve with a Cv of 1 will pass 1 gpm of water with a differential pressure of 1 psi. If you replace the water with CO2, you will pass a lot more than 1 'gpm' of CO2 gas, the amount depending on the pressure and temperature of the CO2.
It's an interesting question, I've never dug back through the sizing formulas for gas {for liquids, it's just Q = Cv * [dP/SG}^.5} to see how they 'relate' to liquids, if they do. But I think for you to find the answer to that question that would be a lot more work than what you are looking for.
RE: Cv correlation between gas and fluid?
Best regrads
Morten
RE: Cv correlation between gas and fluid?
For liquids and low pressure drop gases;
W(lb/hr) = 63.2 * Cv *SQRT {DP(psi)/ sv,i(lbm/ft3)}
For gases where the DP/Pi > 0.05, then use the following :
W=63.2*Cv*Y*SQRT {x*Pi/sv,i}
Y=1-0.33(x/Fk/Xt)
x=min {DP/Pi, Fk/Xt)
Fk=(Cp/1.4/CV) ( this CV is heat capacity)
Xt= valve index for choked flow due to oblique shock waves, typically .75-.85 for globe, .65 angle, 0.2 ball
max value of Y is 0.67 , occurs during choked flow when
x= Fk/Xt
RE: Cv correlation between gas and fluid?
Cv = 15 * D^2 when D is the equivalent orifice diameter in Inches.
You can find this info at http
The lee company is a unique developer and manufacturee\r of micro hydraulic and pneumatic systems for aerospace and commercial uses.
RE: Cv correlation between gas and fluid?
You are incorrect (for most definitions of Cv anyway): Cv is NOT dimensionless (or non dimensionel). Its dimension is GPM water/dP=1psi
Check this link to a TYCO brochure. The last page lists the basic equations.
http://ww
Best regards
Morten
RE: Cv correlation between gas and fluid?
Thank you for the correction. However, what I wanted to emphesis is that Cv is a measure of the equivalent orifice diameter and therefore can be used with any fluid. Meaning is a property of the valve/orifice geometry only. My confussion was because I am used to Cd - discharge coefficient which is more natural to use (at least for me) because it is dimensionless and always less or equall to 1.
RE: Cv correlation between gas and fluid?
Its easy to get confused re this matter. In europe we tend also to favor the dimensionless coefficient (often in Denmark/Germany refered to as K) since this can be used in any pressure/flow relation and not just for a valve.
Best regards
Morten
RE: Cv correlation between gas and fluid?
gpm/sqrt(psid)
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: Cv correlation between gas and fluid?
Best regards
Morten