Orifice sizing clarification
Orifice sizing clarification
(OP)
I am new to orifice sizing.
I am verifying the data from our contractor who sized a flow orifice on a medium pressure (43 bar) steam line to a turbine.Following data is available.
Full range flow = 10000 kg/hr
Operating flow = 5000 kg/hr
Opt. temp = 371 C
Opt press = 43 kg/cm2
Density (Ro) = 15.26 kg/m3
Contractor has provided the following results:
Orifice dia = 72.77 mm
Press drop max = 113.5 in H2O
Press drop opt. = 28.37 in H2O
Reynolds no. = 494253
Discharge coeff = 0.6
I tried to validate the data by using eq. to back calculate the flow rate:
q = CA sq.root(2DP/Ro)
q = m3/s
A = m2
DP = bar
Ro = kg/m3
C=0.6
But the results are far from matching, it comes out 22.2 kg/hr. Please guide for the right equation or anything I am doing wrong, thanks.
I am verifying the data from our contractor who sized a flow orifice on a medium pressure (43 bar) steam line to a turbine.Following data is available.
Full range flow = 10000 kg/hr
Operating flow = 5000 kg/hr
Opt. temp = 371 C
Opt press = 43 kg/cm2
Density (Ro) = 15.26 kg/m3
Contractor has provided the following results:
Orifice dia = 72.77 mm
Press drop max = 113.5 in H2O
Press drop opt. = 28.37 in H2O
Reynolds no. = 494253
Discharge coeff = 0.6
I tried to validate the data by using eq. to back calculate the flow rate:
q = CA sq.root(2DP/Ro)
q = m3/s
A = m2
DP = bar
Ro = kg/m3
C=0.6
But the results are far from matching, it comes out 22.2 kg/hr. Please guide for the right equation or anything I am doing wrong, thanks.





RE: Orifice sizing clarification
Look at the Crane Technical Paper No 410.
Regards.
casflo
RE: Orifice sizing clarification
I prefer the equation in mass flow units, which is:
W = 0.0125217 K d^2 Y1 (Den1 hw)^0.5
W = kg/h
K = C/(1-Beta^4)^0.5
C = roughly 0.61
d = orifice bore, mm
Den1 = inlet density, kg/m3
hw = pres drop, mmH2O, at same tap location as C and Y
Y1 = gas expansion factor
= 1 − (0.41 + 0.35 Beta^4) dP/P1/k for close-up taps
k = Cp/Cv
Cilliers
www.korf.co.uk
RE: Orifice sizing clarification
I've taken above equation from crane papers.
Pipe ID=6 in.
CJKRuger, can you cross check?
Regards,