Pipeline ancillaries
HVB3aslltvoaplveaslve
Simplified equations for sizing (Kv values = Cv x 0.86)
For steam and gases
Where:
Sub-critical flow
When:
DP<0.5 F
L
2P
1
For gases
(volumetric flowrate)
Cv=
��
prT
295 P
1
2 - P
2
2
For gases
(mass flowrate)
Critical flow
When:
DP>0.5 F
L
2P
1
For gases
(volumetric flowrate)
Cv=
��
prT
257 F
L
P
1
For gases
(mass flowrate)
�
�
T
Cv =
311 F
L
P
1
pr
For saturated steam
Cv =
��s
11.95 F
L
P
1
For superheated steam
Cv=
��s(1+0.00126Tso)
11.95 F
L
P
1
Cv =
F
L
=
pr =
P
1
=
P
2
=
T =
V =
m =
Tso =
m
S
=
Flow coeffecient of the valve
Pressure recovery factor
Specific density of gas (air = 1)
Upstream pressure (bar a)
Downstream presure (bar a)
Inlet temperature in °K (°C + 273)
Flowrate of gas in Nm3/h (at 15°C and 1 bar a)
Flowrate of gas in in kg/h
Superheating of steam in °C
(Temperature of superheated steam - Temperature
of saturated steam)
Flowrate of steam in kg/h
T
Cv =
360 (P
1
2 - P
2
2)pr
For saturated steam
Cv =
��s
13.81 P
1
2 - P
2
2
For superheated steam
Cv=
��
s(1+0.00126Tso)
13.81 P
1
2 - P
2
2
Note: These equations are only a simplified version of the
original sizing equations of the ISA and IEC regulations. The
results are sufficiently close for practical use. There could be a
maximum error of 8% in the transition of non-choked flowrate
to choked flowrate.
��
Cv values for reduced bore (RB) valves (Kv values = Cv x 0.86)
Valve
size
Pipe
size
Rotation
0°
9°
18°
27°
36°
45°
54°
63°
72°
81°
90°
1⁄2"
1⁄2"
0.00
0.00
0.22
0.36
0.58
0.88
1.47
2.17
3.50
5.53
7.00
3⁄4"
0.00
0.00
0.22
0.36
0.58
0.88
1.45
2.12
3.29
4.80
5.66
1"
0.00
0.00
0.22
0.36
0.58
0.87
1.44
2.09
3.20
4.53
5.23
3⁄4"
3⁄4"
0.00
0.00
0.37
0.62
0.99
1.50
2.52
3.72
6.00
9.48
12.00
1"
0.00
0.00
0.37
0.62
0.99
1.50
2.50
3.69
5.87
8.98
11.03
11⁄4"
0.00
0.00
0.37
0.62
0.99
1.50
2.49
3.65
5.73
8.52
10.21
11⁄2"
0.00
0.00
0.37
0.62
0.99
1.49
2.48
3.64
5.68
8.35
9.91
1"
1"
0.00
0.00
0.98
1.64
2.61
3.95
6.64
9.80
15.80
24.96
31.60
11⁄4"
0.00
0.00
0.98
1.64
2.61
3.94
6.59
9.63
15.10
22.45
26.91
11⁄2"
0.00
0.00
0.98
1.64
2.60
3.93
6.55
6.52
14.70
21.20
24.83
2"
0.00
0.00
0.98
1.64
2.60
3.92
6.50
9.36
14.15
19.63
22.41
11⁄4"
11⁄4"
0.00
0.00
1.47
2.46
3.90
5.91
9.93
14.66
23.65
37.37
47.30
11⁄2"
0.00
0.00
1.47
2.46
3.90
5.90
9.88
14.50
23.00
34.95
42.66
2"
0.00
0.00
1.47
2.46
3.89
5.88
9.80
14.24
22.00
31.72
37.14
21⁄2"
0.00
0.00
1.47
2.46
3.89
5.87
9.75
14.09
21.47
30.18
34.74
11⁄2"
11⁄2"
0.00
0.00
2.54
4.26
6.77
10.25
17.22
25.42
41.00
64.78
82.00
2"
0.00
0.00
2.54
4.26
6.76
10.21
17.03
24.83
38.65
56.53
66.91
21⁄2"
0.00
0.00
2.54
4.25
6.75
10.18
16.89
24.40
37.08
51.94
59.65
3"
0.00
0.00
2.54
4.25
6.74
10.15
16.75
23.97
35.63
48.16
54.12
2"
11⁄2"
0.00
0.00
3.72
6.24
9.90
15.00
25.20
37.20
60.00
94.80
120.00
21⁄2"
0.00
0.00
3.72
6.24
9.89
14.98
25.10
36.88
58.70
89.92
110.53
3"
0.00
0.00
3.72
6.24
9.88
14.94
24.93
36.33
56.56
82.73
97.93
4"
0.00
0.00
3.72
6.23
9.87
14.90
24.73
35.75
54.43
76.46
87.97
21⁄2"
21⁄2"
0.00
0.00
6.08
10.19
16.17
24.50
41.16
60.76
98.00
154.84
196.00
3"
0.00
0.00
6.08
10.19
16.16
24.46
40.99
60.22
95.79
146.53
179.90
4"
0.00
0.00
6.08
10.18
16.14
24.38
40.60
59.01
91.13
131.31
153.72
6"
0.00
0.00
6.08
10.17
16.11
24.28
40.16
57.67
86.43
118.31
133.91
F
L
- - 0.96 0.94
0.92 0.88 0.82
0.75
0.68
0.62
0.50
M15 ISO Ball Valve for Control of Fluids - Sizing Sheet
TI-P133-46 ST Issue 1
7.4.54
