Control valve sizing and rating (fluids.control_valve)¶
-
fluids.control_valve.
size_control_valve_l
(rho, Psat, Pc, mu, P1, P2, Q, D1=None, D2=None, d=None, FL=0.9, Fd=1, allow_choked=True, allow_laminar=True, full_output=False)[source]¶ Calculates flow coefficient of a control valve passing a liquid according to IEC 60534. Uses a large number of inputs in SI units. Note the return value is not standard SI. All parameters are required. This sizing model does not officially apply to liquid mixtures, slurries, non-Newtonian fluids, or liquid-solid conveyance systems. For details of the calculations, consult [R69].
- Parameters
rho : float
Density of the liquid at the inlet [kg/m^3]
Psat : float
Saturation pressure of the fluid at inlet temperature [Pa]
Pc : float
Critical pressure of the fluid [Pa]
mu : float
Viscosity of the fluid [Pa*s]
P1 : float
Inlet pressure of the fluid before valves and reducers [Pa]
P2 : float
Outlet pressure of the fluid after valves and reducers [Pa]
Q : float
Volumetric flow rate of the fluid [m^3/s]
D1 : float, optional
Diameter of the pipe before the valve [m]
D2 : float, optional
Diameter of the pipe after the valve [m]
d : float, optional
Diameter of the valve [m]
FL : float, optional
Liquid pressure recovery factor of a control valve without attached fittings (normally 0.8-0.9 at full open and decreasing as opened further to below 0.5; use default very cautiously!) []
Fd : float, optional
Valve style modifier (0.1 to 1; varies tremendously depending on the type of valve and position; do not use the default at all!) []
allow_choked : bool, optional
Overrides the automatic transition into the choked regime if this is False and returns as if choked flow does not exist
allow_laminar : bool, optional
Overrides the automatic transition into the laminar regime if this is False and returns as if laminar flow does not exist
full_output : bool, optional
If True, returns intermediate calculation values as well as Kv in the form of a dictionary containing ‘Kv’, ‘Rev’, ‘choked’, ‘FL’, ‘FLP’, ‘FR’, ‘FP’, and ‘laminar’. Some may be None if they are not used in the calculation.
- Returns
Kv : float
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
Notes
It is possible to use this model without any diameters specified; in that case, turbulent flow is assumed. Choked flow can still be modeled. This is not recommended. All three diameters need to be None for this to work. FL and Fd are not used by the models when the diameters are not specified.
References
Examples
From [R69], matching example 1 for a globe, parabolic plug, flow-to-open valve.
>>> size_control_valve_l(rho=965.4, Psat=70.1E3, Pc=22120E3, mu=3.1472E-4, ... P1=680E3, P2=220E3, Q=0.1, D1=0.15, D2=0.15, d=0.15, ... FL=0.9, Fd=0.46) 164.9954763704956
From [R69], matching example 2 for a ball, segmented ball, flow-to-open valve.
>>> size_control_valve_l(rho=965.4, Psat=70.1E3, Pc=22120E3, mu=3.1472E-4, ... P1=680E3, P2=220E3, Q=0.1, D1=0.1, D2=0.1, d=0.1, ... FL=0.6, Fd=0.98) 238.05817216710483
-
fluids.control_valve.
size_control_valve_g
(T, MW, mu, gamma, Z, P1, P2, Q, D1=None, D2=None, d=None, FL=0.9, Fd=1, xT=0.7, allow_choked=True, allow_laminar=True, full_output=False)[source]¶ Calculates flow coefficient of a control valve passing a gas according to IEC 60534. Uses a large number of inputs in SI units. Note the return value is not standard SI. All parameters are required. For details of the calculations, consult [R70]. Note the inlet gas flow conditions.
- Parameters
T : float
Temperature of the gas at the inlet [K]
MW : float
Molecular weight of the gas [g/mol]
mu : float
Viscosity of the fluid at inlet conditions [Pa*s]
gamma : float
Specific heat capacity ratio [-]
Z : float
Compressibility factor at inlet conditions, [-]
P1 : float
Inlet pressure of the gas before valves and reducers [Pa]
P2 : float
Outlet pressure of the gas after valves and reducers [Pa]
Q : float
Volumetric flow rate of the gas at 273.15 K and 1 atm specifically [m^3/s]
D1 : float, optional
Diameter of the pipe before the valve [m]
D2 : float, optional
Diameter of the pipe after the valve [m]
d : float, optional
Diameter of the valve [m]
FL : float, optional
Liquid pressure recovery factor of a control valve without attached fittings (normally 0.8-0.9 at full open and decreasing as opened further to below 0.5; use default very cautiously!) []
Fd : float, optional
Valve style modifier (0.1 to 1; varies tremendously depending on the type of valve and position; do not use the default at all!) []
xT : float, optional
Pressure difference ratio factor of a valve without fittings at choked flow (increasing to 0.9 or higher as the valve is closed further and decreasing to 0.1 or lower as the valve is opened further; use default very cautiously!) [-]
allow_choked : bool, optional
Overrides the automatic transition into the choked regime if this is False and returns as if choked flow does not exist
allow_laminar : bool, optional
Overrides the automatic transition into the laminar regime if this is False and returns as if laminar flow does not exist
full_output : bool, optional
If True, returns intermediate calculation values as well as Kv in the form of a dictionary containing ‘Kv’, ‘Rev’, ‘choked’, ‘Y’, ‘FR’, ‘FP’, ‘xTP’, and ‘laminar’. Some may be None if they are not used in the calculation.
- Returns
Kv : float
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
Notes
It is possible to use this model without any diameters specified; in that case, turbulent flow is assumed. Choked flow can still be modeled. This is not recommended. All three diameters need to be None for this to work. FL and Fd are not used by the models when the diameters are not specified, but xT definitely is used by the model.
References
Examples
From [R70], matching example 3 for non-choked gas flow with attached fittings and a rotary, eccentric plug, flow-to-open control valve:
>>> size_control_valve_g(T=433., MW=44.01, mu=1.4665E-4, gamma=1.30, ... Z=0.988, P1=680E3, P2=310E3, Q=38/36., D1=0.08, D2=0.1, d=0.05, ... FL=0.85, Fd=0.42, xT=0.60) 72.58664545391052
From [R70], roughly matching example 4 for a small flow trim sized tapered needle plug valve. Difference is 3% and explained by the difference in algorithms used.
>>> size_control_valve_g(T=320., MW=39.95, mu=5.625E-5, gamma=1.67, Z=1.0, ... P1=2.8E5, P2=1.3E5, Q=0.46/3600., D1=0.015, D2=0.015, d=0.015, FL=0.98, ... Fd=0.07, xT=0.8) 0.016498765335995726
-
fluids.control_valve.
cavitation_index
(P1, P2, Psat)[source]¶ Calculates the cavitation index of a valve with upstream and downstream absolute pressures P1 and P2 for a fluid with a vapor pressure Psat.
\[\sigma = \frac{P_1 - P_{sat}}{P_1 - P_2}\]- Parameters
P1 : float
Absolute pressure upstream of the valve [Pa]
P2 : float
Absolute pressure downstream of the valve [Pa]
Psat : float
Saturation pressure of the liquid at inlet temperature [Pa]
- Returns
sigma : float
Cavitation index of the valve [-]
Notes
Larger values are safer. Models for adjusting cavitation indexes provided by the manufacturer to the user’s conditions are available, making use of scaling the pressure differences and size differences.
Values can be calculated for incipient cavitation, constant cavitation, maximum vibration cavitation, incipient damage, and choking cavitation.
Has also been defined as:
\[\sigma = \frac{P_2 - P_{sat}}{P_1 - P_2}\]Another definition and notation series is:
\[K = xF = \frac{1}{\sigma} = \frac{P_1 - P_2}{P_1 - P_{sat}}\]References
- R71
ISA. “RP75.23 Considerations for Evaluating Control Valve Cavitation.” 1995.
Examples
>>> cavitation_index(1E6, 8E5, 2E5) 4.0
-
fluids.control_valve.
FF_critical_pressure_ratio_l
(Psat, Pc)[source]¶ Calculates FF, the liquid critical pressure ratio factor, for use in IEC 60534 liquid valve sizing calculations.
\[F_F = 0.96 - 0.28\sqrt{\frac{P_{sat}}{P_c}}\]- Parameters
Psat : float
Saturation pressure of the liquid at inlet temperature [Pa]
Pc : float
Critical pressure of the liquid [Pa]
- Returns
FF : float
Liquid critical pressure ratio factor [-]
References
Examples
From [R72], matching example.
>>> FF_critical_pressure_ratio_l(70100.0, 22120000.0) 0.9442375225233299
-
fluids.control_valve.
is_choked_turbulent_l
(dP, P1, Psat, FF, FL=None, FLP=None, FP=None)[source]¶ Calculates if a liquid flow in IEC 60534 calculations is critical or not, for use in IEC 60534 liquid valve sizing calculations. Either FL may be provided or FLP and FP, depending on the calculation process.
\[\Delta P > F_L^2(P_1 - F_F P_{sat})\]\[\Delta P >= \left(\frac{F_{LP}}{F_P}\right)^2(P_1 - F_F P_{sat})\]- Parameters
dP : float
Differential pressure across the valve, with reducer/expanders [Pa]
P1 : float
Pressure of the fluid before the valve and reducers/expanders [Pa]
Psat : float
Saturation pressure of the fluid at inlet temperature [Pa]
FF : float
Liquid critical pressure ratio factor [-]
FL : float, optional
Liquid pressure recovery factor of a control valve without attached fittings [-]
FLP : float, optional
Combined liquid pressure recovery factor with piping geometry factor, for a control valve with attached fittings [-]
FP : float, optional
Piping geometry factor [-]
- Returns
choked : bool
Whether or not the flow is choked [-]
References
- R73
IEC 60534-2-1 / ISA-75.01.01-2007
Examples
>>> is_choked_turbulent_l(460.0, 680.0, 70.1, 0.94, 0.9) False >>> is_choked_turbulent_l(460.0, 680.0, 70.1, 0.94, 0.6) True
-
fluids.control_valve.
is_choked_turbulent_g
(x, Fgamma, xT=None, xTP=None)[source]¶ Calculates if a gas flow in IEC 60534 calculations is critical or not, for use in IEC 60534 gas valve sizing calculations. Either xT or xTP must be provided, depending on the calculation process.
\[x \ge F_\gamma x_T\]\[x \ge F_\gamma x_{TP}\]- Parameters
x : float
Differential pressure over inlet pressure, [-]
Fgamma : float
Specific heat ratio factor [-]
xT : float, optional
Pressure difference ratio factor of a valve without fittings at choked flow [-]
xTP : float
Pressure difference ratio factor of a valve with fittings at choked flow [-]
- Returns
choked : bool
Whether or not the flow is choked [-]
References
- R74
IEC 60534-2-1 / ISA-75.01.01-2007
Examples
Example 3, compressible flow, non-choked with attached fittings:
>>> is_choked_turbulent_g(0.544, 0.929, 0.6) False >>> is_choked_turbulent_g(0.544, 0.929, xTP=0.625) False
-
fluids.control_valve.
Reynolds_valve
(nu, Q, D1, FL, Fd, C)[source]¶ Calculates Reynolds number of a control valve for a liquid or gas flowing through it at a specified Q, for a specified D1, FL, Fd, C, and with kinematic viscosity nu according to IEC 60534 calculations.
\[Re_v = \frac{N_4 F_d Q}{\nu \sqrt{C F_L}}\left(\frac{F_L^2 C^2} {N_2D^4} +1\right)^{1/4}\]- Parameters
nu : float
Kinematic viscosity, [m^2/s]
Q : float
Volumetric flow rate of the fluid [m^3/s]
D1 : float
Diameter of the pipe before the valve [m]
FL : float, optional
Liquid pressure recovery factor of a control valve without attached fittings []
Fd : float
Valve style modifier [-]
C : float
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
- Returns
Rev : float
Valve reynolds number [-]
References
- R75
IEC 60534-2-1 / ISA-75.01.01-2007
Examples
>>> Reynolds_valve(3.26e-07, 360, 150.0, 0.9, 0.46, 165) 2966984.7525455453
-
fluids.control_valve.
loss_coefficient_piping
(d, D1=None, D2=None)[source]¶ Calculates the sum of loss coefficients from possible inlet/outlet reducers/expanders around a control valve according to IEC 60534 calculations.
\[\Sigma \xi = \xi_1 + \xi_2 + \xi_{B1} - \xi_{B2}\]\[\xi_1 = 0.5\left[1 -\left(\frac{d}{D_1}\right)^2\right]^2\]\[\xi_2 = 1.0\left[1 -\left(\frac{d}{D_2}\right)^2\right]^2\]\[\xi_{B1} = 1 - \left(\frac{d}{D_1}\right)^4\]\[\xi_{B2} = 1 - \left(\frac{d}{D_2}\right)^4\]- Parameters
d : float
Diameter of the valve [m]
D1 : float
Diameter of the pipe before the valve [m]
D2 : float
Diameter of the pipe after the valve [m]
- Returns
loss : float
Sum of the four loss coefficients [-]
References
- R76
IEC 60534-2-1 / ISA-75.01.01-2007
Examples
In example 3, non-choked compressible flow with fittings:
>>> loss_coefficient_piping(0.05, 0.08, 0.1) 0.6580810546875
-
fluids.control_valve.
Reynolds_factor
(FL, C, d, Rev, full_trim=True)[source]¶ Calculates the Reynolds number factor FR for a valve with a Reynolds number Rev, diameter d, flow coefficient C, liquid pressure recovery factor FL, and with either full or reduced trim, all according to IEC 60534 calculations.
If full trim:
\[F_{R,1a} = 1 + \left(\frac{0.33F_L^{0.5}}{n_1^{0.25}}\right)\log_{10} \left(\frac{Re_v}{10000}\right)\]\[F_{R,2} = \min(\frac{0.026}{F_L}\sqrt{n_1 Re_v},\; 1)\]\[n_1 = \frac{N_2}{\left(\frac{C}{d^2}\right)^2}\]\[F_R = F_{R,2} \text{ if Rev < 10 else } \min(F_{R,1a}, F_{R,2})\]Otherwise :
\[F_{R,3a} = 1 + \left(\frac{0.33F_L^{0.5}}{n_2^{0.25}}\right)\log_{10} \left(\frac{Re_v}{10000}\right)\]\[F_{R,4} = \frac{0.026}{F_L}\sqrt{n_2 Re_v}\]\[n_2 = 1 + N_{32}\left(\frac{C}{d}\right)^{2/3}\]\[F_R = F_{R,4} \text{ if Rev < 10 else } \min(F_{R,3a}, F_{R,4})\]- Parameters
FL : float
Liquid pressure recovery factor of a control valve without attached fittings []
C : float
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
d : float
Diameter of the valve [m]
Rev : float
Valve reynolds number [-]
full_trim : bool
Whether or not the valve has full trim
- Returns
FR : float
Reynolds number factor for laminar or transitional flow []
References
- R77
IEC 60534-2-1 / ISA-75.01.01-2007
Examples
In Example 4, compressible flow with small flow trim sized for gas flow (Cv in the problem was converted to Kv here to make FR match with N32, N2):
>>> Reynolds_factor(FL=0.98, C=0.015483, d=15., Rev=1202., full_trim=False) 0.7148753122302025
-
fluids.control_valve.
Cv_char_quick_opening
(opening)¶
-
fluids.control_valve.
Cv_char_linear
(opening)¶
-
fluids.control_valve.
Cv_char_equal_percentage
(opening)¶
-
fluids.control_valve.
convert_flow_coefficient
(flow_coefficient, old_scale, new_scale)[source]¶ Convert from one flow coefficient scale to another; supports the Kv Cv, and Av scales.
Other scales are Qn and Cg, but clear definitions have yet to be found.
- Parameters
flow_coefficient : float
Value of the flow coefficient to be converted, expressed in the original scale.
old_scale : str
String specifying the original scale; one of ‘Av’, ‘Cv’, or ‘Kv’, [-]
new_scale : str
String specifying the new scale; one of ‘Av’, ‘Cv’, or ‘Kv’, [-]
- Returns
converted_flow_coefficient : float
Flow coefficient converted to the specified scale.
Notes
Qn is a scale based on a flow of air in units of L/minute as air travels through a valve and loses one bar of pressure (initially 7 bar absolute, to 6 bar absolute). No consistent conversion factors have been found and those from theory do not match what have been found. Some uses of Qn use its flow rate as in normal (STP reference conditions) flow rate of air; others use something like the 7 bar absolute condition.
Examples
>>> convert_flow_coefficient(10, 'Kv', 'Av') 0.0002776532068951358
-
fluids.control_valve.
control_valve_choke_P_l
(Psat, Pc, FL, P1=None, P2=None, disp=True)[source]¶ Calculates either the upstream or downstream pressure at which choked flow though a liquid control valve occurs, given either a set upstream or downstream pressure. Implements an analytical solution of the needed equations from the full function
size_control_valve_l
. For some pressures, no choked flow is possible; for choked flow to occur the direction if flow must be reversed. If disp is True, an exception will be raised for these conditions.\[P_1 = \frac{F_{F} F_{L}^{2} P_{sat} - P_{2}}{F_{L}^{2} - 1}\]\[P_2 = F_{F} F_{L}^{2} P_{sat} - F_{L}^{2} P_{1} + P_{1}\]- Parameters
Psat : float
Saturation pressure of the liquid at inlet temperature [Pa]
Pc : float
Critical pressure of the liquid [Pa]
FL : float, optional
Liquid pressure recovery factor of a control valve without attached fittings [-]
P1 : float, optional
Absolute pressure upstream of the valve [Pa]
P2 : float, optional
Absolute pressure downstream of the valve [Pa]
disp : bool, optional
Whether or not to raise an exception on flow reversal, [-]
- Returns
P_choke : float
Pressure at which a choke occurs in the liquid valve [Pa]
Notes
Extremely cheap to compute.
Examples
>>> control_valve_choke_P_l(69682.89291024722, 22048320.0, 0.6, 680000.0) 458887.5306077305 >>> control_valve_choke_P_l(69682.89291024722, 22048320.0, 0.6, P2=458887.5306077305) 680000.0
-
fluids.control_valve.
control_valve_choke_P_g
(xT, gamma, P1=None, P2=None)[source]¶ Calculates either the upstream or downstream pressure at which choked flow though a gas control valve occurs, given either a set upstream or downstream pressure. Implements an analytical solution of the needed equations from the full function
size_control_valve_g
. A singularity arises as xT goes to 1 and gamma goes to 1.4.\[P_1 = - \frac{7 P_{2}}{5 \gamma x_T - 7}\]\[P_2 = \frac{P_{1}}{7} \left(- 5 \gamma x_T + 7\right)\]- Parameters
xT : float, optional
Pressure difference ratio factor of a valve without fittings at choked flow [-]
gamma : float
Specific heat capacity ratio [-]
P1 : float, optional
Absolute pressure upstream of the valve [Pa]
P2 : float, optional
Absolute pressure downstream of the valve [Pa]
- Returns
P_choke : float
Pressure at which a choke occurs in the gas valve [Pa]
Notes
Extremely cheap to compute.
Examples
>>> control_valve_choke_P_g(1, 1.3, 1E5) 7142.857142857143 >>> control_valve_choke_P_g(1, 1.3, P2=7142.857142857143) 100000.0
-
fluids.control_valve.
control_valve_noise_l_2015
(m, P1, P2, Psat, rho, c, Kv, d, Di, FL, Fd, t_pipe, rho_pipe=7800.0, c_pipe=5000.0, rho_air=1.2, c_air=343.0, xFz=None, An=-4.6)[source]¶ Calculates the sound made by a liquid flowing through a control valve according to the standard IEC 60534-8-4 (2015) [R78].
- Parameters
m : float
Mass flow rate of liquid through the control valve, [kg/s]
P1 : float
Inlet pressure of the fluid before valves and reducers [Pa]
P2 : float
Outlet pressure of the fluid after valves and reducers [Pa]
Psat : float
Saturation pressure of the fluid at inlet temperature [Pa]
rho : float
Density of the liquid at the inlet [kg/m^3]
c : float
Speed of sound of the liquid at the inlet conditions [m/s]
Kv : float
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
d : float
Diameter of the valve [m]
Di : float
Internal diameter of the pipe before and after the valve [m]
FL : float, optional
Liquid pressure recovery factor of a control valve without attached fittings (normally 0.8-0.9 at full open and decreasing as opened further to below 0.5) [-]
Fd : float, optional
Valve style modifier [-]
t_pipe : float
Wall thickness of the pipe after the valve, [m]
rho_pipe : float, optional
Density of the pipe wall material at flowing conditions, [kg/m^3]
c_pipe : float, optional
Speed of sound of the pipe wall material at flowing conditions, [m/s]
rho_air : float, optional
Density of the air surrounding the valve and pipe wall, [kg/m^3]
c_air : float, optional
Speed of sound of the air surrounding the valve and pipe wall, [m/s]
xFz : float, optional
If specified, this value xFz is used instead of estimated; the calculation is sensitive to this value, [-]
An : float, optional
Valve correction factor for acoustic efficiency
- Returns
LpAe1m : float
A weighted sound pressure level 1 m from the pipe wall, 1 m distance dowstream of the valve (at reference sound pressure level 2E-5), [dBA]
Notes
For formulas see [R78]. This takes on the order of 100 us to compute. This model can also tell if noise is being produced in a valve just due to turbulent flow, or cavitation. For values of An, see [R78]; it is normally -4.6 for globel valves, -4.3 for butterfly valves, and -4.0 for expanders.
This model was checked against three examples in [R78]; they match to all given decimals.
A formula is given in [R78] for multihole trim valves to estimate xFz as well; this is not implemented here and xFz must be calculated by the user separately. The formula is
\[x_{Fz} = \left(4.5 + 1650\frac{N_0d_H^2}{F_L}\right)^{-1/2}\]Where N0 is the number of open channels and dH is the multihole trim hole diameter.
References
- R78(1,2,3,4,5,6)
IEC 60534-8-4 : Industrial-Process Control Valves - Part 8-4: Noise Considerations - Prediction of Noise Generated by Hydrodynamic Flow. (2015)
Examples
>>> control_valve_noise_l_2015(m=40, P1=1E6, P2=6.5E5, Psat=2.32E3, ... rho=997, c=1400, Kv=77.848, d=0.1, Di=0.1071, FL=0.92, Fd=0.42, ... t_pipe=0.0036, rho_pipe=7800.0, c_pipe=5000.0,rho_air=1.293, ... c_air=343.0, An=-4.6) 81.58200097996539
-
fluids.control_valve.
control_valve_noise_g_2011
(m, P1, P2, T1, rho, gamma, MW, Kv, d, Di, t_pipe, Fd, FL, FLP=None, FP=None, rho_pipe=7800.0, c_pipe=5000.0, P_air=101325.0, rho_air=1.2, c_air=343.0, An=-3.8, Stp=0.2, T2=None, beta=0.93)[source]¶ Calculates the sound made by a gas flowing through a control valve according to the standard IEC 60534-8-3 (2011) [R79].
- Parameters
m : float
Mass flow rate of gas through the control valve, [kg/s]
P1 : float
Inlet pressure of the gas before valves and reducers [Pa]
P2 : float
Outlet pressure of the gas after valves and reducers [Pa]
T1 : float
Inlet gas temperature, [K]
rho : float
Density of the gas at the inlet [kg/m^3]
gamma : float
Specific heat capacity ratio [-]
MW : float
Molecular weight of the gas [g/mol]
Kv : float
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
d : float
Diameter of the valve [m]
Di : float
Internal diameter of the pipe before and after the valve [m]
t_pipe : float
Wall thickness of the pipe after the valve, [m]
Fd : float
Valve style modifier (0.1 to 1; varies tremendously depending on the type of valve and position; do not use the default at all!) [-]
FL : float
Liquid pressure recovery factor of a control valve without attached fittings (normally 0.8-0.9 at full open and decreasing as opened further to below 0.5; use default very cautiously!) [-]
FLP : float, optional
Combined liquid pressure recovery factor with piping geometry factor, for a control valve with attached fittings [-]
FP : float, optional
Piping geometry factor [-]
rho_pipe : float, optional
Density of the pipe wall material at flowing conditions, [kg/m^3]
c_pipe : float, optional
Speed of sound of the pipe wall material at flowing conditions, [m/s]
P_air : float, optional
Pressure of the air surrounding the valve and pipe wall, [Pa]
rho_air : float, optional
Density of the air surrounding the valve and pipe wall, [kg/m^3]
c_air : float, optional
Speed of sound of the air surrounding the valve and pipe wall, [m/s]
An : float, optional
Valve correction factor for acoustic efficiency
Stp : float, optional
Strouhal number at the peak fp; between 0.1 and 0.3 typically, [-]
T2 : float, optional
Outlet gas temperature; assumed T1 if not provided (a PH flash should be used to obtain this if possible), [K]
beta : float, optional
Valve outlet / expander inlet contraction coefficient, [-]
- Returns
LpAe1m : float
A weighted sound pressure level 1 m from the pipe wall, 1 m distance dowstream of the valve (at reference sound pressure level 2E-5), [dBA]
Notes
For formulas see [R79]. This takes on the order of 100 us to compute. For values of An, see [R79].
This model was checked against six examples in [R79]; they match to all given decimals.
Several additional formulas are given for multihole trim valves, control valves with two or more fixed area stages, and multipath, multistage trim valves.
References
- R79(1,2,3,4,5)
IEC 60534-8-3 : Industrial-Process Control Valves - Part 8-3: Noise Considerations - Control Valve Aerodynamic Noise Prediction Method.”
Examples
>>> control_valve_noise_g_2011(m=2.22, P1=1E6, P2=7.2E5, T1=450, rho=5.3, ... gamma=1.22, MW=19.8, Kv=77.85, d=0.1, Di=0.2031, FL=None, FLP=0.792, ... FP=0.98, Fd=0.296, t_pipe=0.008, rho_pipe=8000.0, c_pipe=5000.0, ... rho_air=1.293, c_air=343.0, An=-3.8, Stp=0.2) 91.67702674629604