CONTROL VALVE
USER GUIDEControlvalve Regulation valve sizing
Version Creation date Correspondant Last revision
This calculation sheet is the property of the …... and shall not be disclosed to others or reproduced
in any manner without its permission.
Databook has to be read and assimilated before using the worksheet.
It is advised to make the first calculation by hand in order to have a better comprehension of the method applied. 1 REFERENCE
This note is in accordance with the international standard for sizing control valves
2 ASSUMPTIONS
Calculation consider valves without adjacent fittings They are made for turbulent flowrates
3 DOMAIN OF VALIDITY NA
4 FORMULAS
4.1.Symbols
Cv = valve sizing coefficient q = Volumetric flowrate(m3/h) W = Mass flowrate (kg/h)
P1 = Upstream absolute static pressure P2 = downstream absolute static pressure
Pv = Absolute vapor pressure of liquid at inlet temperature. Pc = Absolute thermodynamic critical pressure
Gf = liquid specific gravity (ratio of density of liquid on density of water) T1= Absolute upstream temperature °K
Z = Compressibility factor M = gas molecular weight
d1=Downstream density of blend, kg/m3 d2=Downstream density of blend, kg/m3 W1l=upstream liquid flow, kg/h W2l=downstream liquid flow, kg/h W1v=upstream vapor flow, kg/h W2v=downstream vapor flow, kg/h d1l=upstream liquid density, kg/m3 d2l=Downstream liquid density, kg/m3 d1v=upstream vapor density, kg/m3 d2v=Downstream vapor density, kg/m3
5 OBJECTIVE
This worksheet permits to calculate :
- The Cv of the valve for liquid, vapor or two phase flows.
Cv is the sizing coefficient used to characterize the flow capacity of valves. It corresponds to the number of US gallons flowing though the valve in one minute when the valve differential pressure is 1 PSI.
- The flowrate circulating across the valve for a given Cv will be calculated with a manual approach of the specific flowrate. 6 INPUT
Input have to be filled into yellow boxes
xT and Cf coefficients depend on the kind of valve. Their values for the main types of valves are recorded in the sheet "table". Default values are atribuate to coefficients gamma, xT and Cf if the corresponding cells are kept empty (Cf cells comments) Curves describing the Cv % evolution in function of the shutting valve is available in the guard "opening"
This evolution can be simulated with parabolic (P), linear (L), equal % (%) ou quick opening (QO) curves
All formulas are available in the sheet " Formulas_comparison". Formulas enclosed in blue are used in the sheet "design"
Cf = Factor of critical flow given by the constructor ( is equivalent to the FL coefficient: pressure recovery factor) xT = rated pressure drop ratio factor
FF = factor resulting from the liquid critical pressure Fγ= factor corresponding to the specific heat ratio
γf = mass fraction of the liquid phase
CONTROL VALVE Calculation note
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CONTROL VALVE FORMULAS
DATABOOK FORMULATIONS MASONEILAN FORMULATIONS FISCHER FORMULATION (ANSI/ ISA/IEC)
non critical flow
critical flow WITH
Compressible fluids
non engorged
is limited to 0.667 Engorged
Two phase flow
Avec vaporisation de liquide WITH
Avec
limited to
limited to
Sans vaporisation de liquide
NOTE
1) In the calculation sheet:
2)
3) Fitting attached to valve can have a significant impact for high recovery valves ( example: rotary valves like butterfly or ball valves) which 4) Fr= facteur du nombre de Reynolds Si Rev<56; Fr=0.019 (Rev)^0.67
Si Rev>40000; Fr=1
Si 56<Re<40000; cf coubes de Fisher (p2-7) 5) Formulation enclosed in blue are used in the sheet "design"
Liquid Service non critical critical ∆P est limité à 0.5 * Cf ² *P1 ∆P est limité à 0.5 * Cf ² *P1
It is considered a valve installed without adjacent fitting and so FP =1 It is considered a turbulent flow and so FR =1
If it is considered fitting attached to the valve, xT should be replaced by xTP which combine xT and piping geometry factor
have a rather low pressure drop coefficient at full opening. Manufactrers often provide FP values for swages installed adjacent to such rotary valves.
C
V
=
w
2 7.3∗C
f
∗
F
P
∗
F
R
∗
Δ P s∗γ 1
ΔPC
f²* ΔP
s
ΔP≥C
f²* ΔP
s
xF γ∗x
T
x≥F γ∗x
T
C
V=
W
94.8∗F
P∗
P1∗0.667
∗
T1∗Z
Fγ∗x
T∗
M
Fγ = γ 1 . 4x=
ΔP
P1
C
V
=
W
2 7.3
∗
f
f
Δ p
f
∗γf
f
g
Δ P
g
∗γ
g
∗Y ²
P1−P21 2∗Cf²* P1C
V=
q
2 9 5
∗
G∗T∗Z
P
1−
P
2
P
1
P
2
P1−P2≥1 2∗Cf²* P1C
V=
q
257∗C
f∗
P
1∗
G∗T∗Z
ΔP
f=
P1−P2
Δ P
g=
P 1−P 2
Δ P
f=
C
f²* P 1−F
F∗
P
v
ΔP
g=
F
γ∗
x
T∗
P
1C
V=
51.8∗W
ΔP∗ d1d2
C
V=
36. 6∗W
ΔP∗d1
d1=
W∗103
W 1l
d1l
W 1v
d1v
d 2=
W∗1 03
W 2 l
d 2 l
W 2 v
d 2 v
C
V=
W
94.8∗F
P∗
P1∗Y
∗
T1∗Z
x∗M
Y =1−
x
3∗F γ∗x
TC
V
=
w
27.3∗F
P
∗
F
R
∗
ΔP∗γ1
ΔP
s=
P
1−
0 . 96−0 . 28∗
P
vP
c∗
P
vY =1−
x
3∗F γ∗x
TFγ=
γ
1.4
Y=1−
Δ P
G
3∗F γ∗x
T
∗P 1
CONTROL VALVE
Activity-unit: N° Date Revision Issued by Checked byItem old old old old old old
Service
Case DESIGN DESIGN DESIGN DESIGN DESIGN DESIGN
P R E S S U R
E Inlet Pressure bar (g)
Pressure Drop bar 0.0 0.0 0.0 0.0 0.0 0.0
Outlet pressure bar (g)
F LO W Temperature °C Vap. FlowRate kg/hr Liq. FlowRate kg/hr Total FlowRate kg/hr Over margin % Flow Rate kg/hr V A P O U R
Vapour Fraction (weigth)
Molecular Weigth
Viscosity cP #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
Compressibility Cp/Cv (= gamma)
Density @(0 ATM,15.66°C) kg/m3 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
Density @ cond. kg/m3 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
LI Q U ID Density Viscosity cP
Critical Pressure bar a
Vapour Pressure bar a
Fluid (liq +vap) Density kg/m3
V
A
LV
E (Cf table)
Flow regime
Calculated Cv (If two phase flow : Cv= Cv gas + Cv liq )
Installed Cv
Opening Law (QO / % / L / P )
Openning % Margin @ 80% opening % (g) O P E N IN G Quick Opening Equal Percentage Linear Parabolic Quick Opening Equal Percentage Linear Parabolic
In the case of 2 phase flow with incondensable liquid and incondensable gas or with a liquid mixing to its own vapor, Cv value is calculated hereafter:
Cv NOTES:
kg/m3
XT (coefficient of rate from the diferential pressure of a regulation valve with no adjacent link , at engorged flow): Cf Table
Cf F LO W C H A R A C -T E R IS T IC M A X F L O W @ 8 0% O P E N IN G
CONTROL VALVE
Calculation note
Property of TECHNIP. Reproduction, Copying, Distribution to Others not Authorized
57355303.xls
CONTROL VALVE
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
% Cv
%
o
p
e
n
in
g
CONTROL VALVE
Opening law definition in function of the % Cv
%Opening
Linearization
%Cv
Q op
Eq %
MP
L
Q op
Eq %
P
0
0
0
0
0.0
0.0
0.0
5
3.2
21.5
15
5
3.1
20.1
14.4
10
5.9
37
24.5
10
5.9
38.6
25.1
20
11
55.5
39
20
11.0
57.1
38.8
30
16
67
47.5 47.5
30
16.0
67.9
47.9
40
21.5
75.3
55
40
21.4
75.6
55.3
50
27
81
63
50
26.9
81.5
62.8
60
32
86
70
60
32.3
86.4
70.2
70
38
90.5
77.5
70
38.0
90.5
77.7
80
47
85
80
46.3
94.0
85.1
90
61.5
92
90
63.1
97.2
92.6
95
79.5
95
78.1
98.6
96.3
100
100
100
100
100
100.4
100.0
100.0
% Cv @ 80% opening
Q op
Eq %
P
79.999
80
80
95.5
47.25
73.12
CONTROL VALVE Calculation note
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