PSV Sizing
PRV set pressure
Accumulation
Pressure at PRV inlet
Temperature at PRV inlet
Liquid heat capacity
Specific volume of two-phase system
Specific volume of vapor
Vapor mass fraction
Po
T
Cp
Vo
Vvo
xo
hvlo
latent heat of vaporization
Ratio of specific heats of vapor
vapor & liquid specific vol. difference
k
Vvlo
Sp. Vol evaluated at 90% of Po
Omega Parameter
V9
Selected Value of Omega
Crictical Pressure Ratio
Downstream Back pressure
Crictical Pressure
(two phase flow)
psig
%
psia
R
btu/lb.R
ft3/lb
ft /lb
btu/lb
for D.2, D.4
for D.1, D.2
ft /lb
3
psia
Flow is
a
Mass Flux
Mass Flow Rate
Discharge Coefficient
Back Presure Correction Factor
Correction Factor For Rupture disk
G
W
Kd
Kb
Kc
0.3116
Pa
Pc
back pressure ratio
60
10
80.7
0.3629 for D.3
#DIV/0! D.1
#DIV/0! D.2
1.482 D.3
#DIV/0! D.4
1.482
0.66 from graph D.1
29.7
53.262
Critical Flow
0.36803
lb/s.ft2
lb/hr
594.07
477430
0.85
1 from graph D.2
1
Calculated Area of the Orifice
in2
37.82
Selected Orifice Designation
in2
#N/A
INPUT
OUTPUT
or D.2, D.4
or D.1, D.2
Boiling Range < 150 F
Boiling Range < 150 F
Boiling Range > 150 F
For Nonflashing systems
om graph D.1
om graph D.2
Pc > Pa
Pc < Pa
Critical Flow
Sub-Critical Flow
API Orifice
Designations
D
0.11
E
0.196
0.11
0.196
0.307
0.307
G
H
0.503
0.785
0.503
0.785
J
K
1.287
1.838
1.287
1.838
2.853
2.853
M
N
P
Q
R
T
3.6
4.34
6.38
11.05
16
26
3.6
4.34
6.38
11.05
16
26
D
E
F
G
H
J
K
L
M
N
P
Q
R
T
PSV Sizing
PRV set pressure
Accumulation
(two phase flow)
psig
%
260
10
300.7
Pressure at PRV inlet
Po
psia
Temperature at PRV inlet
Saturation Pressure at To
To
519.67
Ps
Liquid heat capacity
Cp
lo
psia
btu/lb.R
107.6
0.6365
Liquid density at PRV inlet
lb/ft3
lb/ft3
hvls
btu/lb
vapor & liquid specific vol. difference
Omega Parameter
Vvls
ft3/lb
Selected Value of Omega
Transition saturation pressure ratio
s
st
Saturation Pressure Ratio
Critical Pressure Ratio
Downstream Back pressure
Crictical Pressure
Density at 90% of Ps
latent heat of vaporization at Ps
Pa
Pc
152.3
0.9684
8.497 D.8
#DIV/0! D.9
8.5
0.358
psia
back pressure ratio
Mass Flux
lb/s.ft2
Volumetric Flow Rate
Discharge Coefficient
Back Presure Correction Factor
Correction Factor For Rupture disk
Q
Kd
Kb
Kc
GPM
A
F
in2
Selected Orifice Designation
for D.9
0.944
High Subcooling Region
Flow is
Calculated Area of the Orifice
31.92
from graph D.3 (used for L
24.7
0 used for Low Sub cooling
Critical Flow
0.082
in
#DIV/0! D.10 for Low Subcooling R
7560.47 D.11 for High Subcooling
100
0.65
1 use graph D.4
1
0.21
0.307
INPUT
OUTPUT
Boiling Range < 150 F
Boiling Range >150 F
oling Region
om graph D.3 (used for Low Sub cooling Region)
sed for Low Sub cooling Region
.10 for Low Subcooling Region
.11 for High Subcooling Region
se graph D.4
API Orifice
Designations
D
0.11
E
F
0.196
0.307
0.11
0.196
0.503
0.307
0.785
0.503
1.287
0.785
K
L
M
N
1.838
2.853
3.6
4.34
1.287
1.838
2.853
3.6
P
Q
6.38
11.05
4.34
6.38
16
11.05
26
16
26
D
E
F
G
H
J
K
L
M
N
P
Q
R
T
PSV Sizing
PRV set pressure
Accumulation
(two phase flow)
psig
%
600
10
674.7
Pressure at PRV inlet
Po
psia
Temperature at PRV inlet
To
Vapor mass fraction at PRV inlet
xo
Specific volume of vapor
Specific volume of two phase system
Saturation Pressure at To
Noncondensable gas partial pressure
Liquid heat capacity
Liquid density at PRV inlet
Specific volume at 90% of Pvo
909.67
0.5596
Vvgo
ft3/lb
0.2462
Vo
ft3/lb
0.1549
Pvo
psia
Pgo
psia
btu/lb.R
Cp
lo
lb/ft3
v9
lb/ft3
Latent heat of vaporization at PRV inlet
hvlo
btu/lb
Vapor & liquid specific vol. difference
Ratio of specific heats
Vvlo
ft3/lb
Inlet void fraction
Omega Parameter
0.1737 for D.15
k
o
Nonflashing Critical Pressure Ratio
gc
Flashing Critical Pressure Ratio
vc
Critical Pressure Ratio
Downstream Back pressure
Crictical Pressure
c
Pa
Pc
0.8894
If Conditions Satisfied
#DIV/0! D.14
from graph D.1
from graph D.1
Not Required
psia
0
Subcritical Flow
Flow is
Back Pressure Ratio
Non flashing partial pressure ratio
Flashing partial pressure ratio
#DIV/0!
#DIV/0!
Mass Flux
lb/s.ft2
#DIV/0! for Critical Flow
Non flashing Mas flux
Gg
lb/s.ft
#DIV/0!
Flashing Mass flux
Gv
lb/s.ft
Err:502
Mass Flux
Mass Flow Rate
Discharge Coefficient
Back Presure Correction Factor
Correction Factor For Rupture disk
G
W
Kd
Kb
Kc
lb/s.ft
lb/hr
#DIV/0! for Subcritical Flow
0.85
1 use graph D.2
1
in2
#DIV/0! for Critical Flow
Calculated Area of the Orifice
in2
#DIV/0! for Subcritical Flow
Selected Orifice Designation
in
#DIV/0! for Critical Flow
in
Calculated Area of the Orifice
Selected Orifice Designation
A
#DIV/0!
#DIV/0!
for Subcritical Flow
INPUT
OUTPUT
For systems that satisfy all the following conditions, use D.
itions Satisfied
If Conditions Not Satisfied
1.0923 D.15
om graph D.1
Not Required
om graph D.1
Not Required
0.62 from graph D.1
69.7
418.314
Critical Flow
iterate g
& v to get
same
values in
G31 & G32
or Critical Flow
0.103305
2665.816
or Subcritical Flow
se graph D.2
153830
0.85
1 use graph D.2
1
or Critical Flow
2.72
or Subcritical Flow
or Critical Flow
or Subcritical Flow
2.853
lowing conditions, use D.14 otherwise use D.15
API Orifice
Designations
D
0.11
0.196
0.11
0.307
0.196
0.503
0.307
0.785
0.503
J
K
1.287
1.838
0.785
1.287
2.853
1.838
3.6
2.853
4.34
3.6
P
Q
6.38
11.05
4.34
6.38
R
T
16
26
11.05
16
26
D
E
F
G
H
J
K
L
M
N
P
Q
R
T
D.1
D.2
D.3
D.4
