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ENGINEERING DESIGN CALCULATION - DENNIS KIRK
Compressible Fluid Flow Through Thin Square Edge Orifice Plates
Ver 1.000
Calculation utilises data from Cunningham (ASME 1951) to extend the typical orifice calculation limits of P
2
'/P
1
' > 0.8 or 0.6
Calculation is valid for 1.0 > P
2
'/P
1
' > 0 and 0.8 >
> 0.1 and is similar to AGA 3 for 1.0 > P
2
'/P
1
' > 0.8
Upstream Pipe ID
D
100
mm
Orifice ID
d
50
mm
Orifice Area
1963.5
mm
2
Beta Ratio
0.500
OK
Upstream Pressure
P
1
4000
kPa(g)
P
1
'
4101.325
kPa(a)
Differential Press.
dP
4000
kPa
Downstream Pressure
P
2
0
kPa(g)
P
2
'
101.325
kPa(a)
Molecular Weight
MW
29
CO
2
0
mole%
N
2
0
mole%
Zbase
0.993
SGreal
1.008
Specific Heat Ratio
g
1
- from tables
1.4
Upstream Temperature
T
1
25
°C
T
1
'
298.15
°K
Absolute Viscosity
1
0.014
cP
Compressibility Factor
Z
1
- from AGA 8 GCM2
0.659
Density
72.779
kg/m
3
1.235
kg/Sm
3
Inflection Pressure Ratio
[Cunningham]
0.63
Actual Pressure Ratio
Use Second Equation for Y
0.025
0.975
Expansion Factor
for P2 >
2483 kPa(g)
0.699
for P2 <
2483 kPa(g)
0.662
Reynolds Number
17,732,244
Discharge Coefficient
Cd(FT) - from AGA 3 method for Flange Taps
0.60205
OK
Velocity of Approach Factor
1.03280
Flow Coefficient
AGA 3
0.62179
or Cunningham
for fully turbulent flow
0.63394
not used in calculation
Volumetric Flowrate
0.2679
Am
3
/sec
15.7830
Sm
3
/sec
Mass Flowrate
19.4976
kg/sec
Velocity Upstream
v1
34.110
m/sec
www.ozemail.com.au/~denniskb
denniskb@ozemail.com.au
1
2
3
1
1
1
1
2
2.
.1000
/ sec
. . .
/ sec
. . . 2. .
.1000
o
o
P
P
q Am
Y C A
w kg
Y C A
P
P
1
1
1
1
. '
.8.3145. '
MW P
Z
T
2
1
4
'
1
'
1
0.41 0.35.
.
P
P
Y
k
2
1
4
0.63
'
0.63
'
0.49 0.45.
.
P
P
Y
Y
k
2
.
4
o
d
A
4
1
1
v
E
d
D
.
d
v
C C E
2
1
'
'
P
r
P
6
1
1
1
1
1
. .
4. .10
Re
. .
D v
w
D
4
0.608 0.415.
C
1
'
'
dP
r
P
Orifice_New.xls
CriticalOrifice
19/12/2005
