CALCULATE : CvCALCULATE : Cv
The Cv is the universal yardstick of valve capacity. By definition, the valve flow coefficient (Cv), is the number of gallons per minute of water that will pass through a given flow restrction with a pressure drop of one psi.
 |
The Cv can be calculate for the following equations, when you have two fase |
where
Cv is the valve flow coefficient
w is the weight flow rate of two phase mixture (lb/h)
Fp is the piping gewometry factor (reducer correction)
fl is the weight fraction of liquid in two phase mixture
fg is the weight fraction of gas (or vapor of liquid) in two phase mixture
Þl is the mass density of the liquid phase at inlet conditions (lb/ft3)
Þg is the mass density of the gas or vapor phase at inlet conditions (lb/ft3)
is the pressure drop for the liquid phase (psia)
is
the pressure drop for the gas phase (psia)
y is then gas expansion factor.
|
The Cv can be calculate for the following equations, when you have liquid fase |
Cv is the valve flow coefficient
Wc is the weight flow rate of two phase mixture (lb/h)
|
The Cv can be calculate for the following equations, when you have gas fase |
Cv is the valve flow coefficient
Wc is the weight flow rate of two phase mixture (lb/h)
z factor correcction.