Good Morning Team,
I have a high performance butterfly control valve in a vent line (50 DN)which connects to the vacuum line(150 DN) and this vacuum line end as suction line of vacuum pump through which vacuum produced for entire system. I have to size this control valve. Operating pressure of this vacuum line is 0.2-0.44 bar(a).To calculate the inflow rate of air for this valve,I was using a formula
q = 678 * Y * d2 * C * [DP * P1 / (T1 * Sg) ]½
where: q = Air Flow, SCFM
Y = Expansion Factor .79 (for vacuum sizing) .85 (for exhaust sizing at 5 psi) .93 (for exhaust sizing at 2 psi)
d = Valve Diameter, in
DP = Delta Pressure, psi The lower of 5 psi or pipe collapse pressure (for vacuum sizing) 2 or 5 psi (for exhaust sizing) P1 = Inlet Pressure, psia 14.7 (for vacuum sizing) 16.7 or 19.7 psia (for exhaust sizing at 2 or 5 psi)
T1 = Inlet Temperature = 520 Rankine
Sg = Specific Gravity = 1 for air
C = Discharge Coefficient = .7 for square edge orifice
from below reference.
http://www.valmatic....gAVs_4-7-15.pdf
Am i proceeding in right direction ? if not please help me out in this topic, how to size this valve i.e.how to calculate inflow rate of air ?
Thanks in Advance