Control valve sizing and rating (fluids.control_valve)¶
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fluids.control_valve.
Cv_char_equal_percentage
(opening)¶
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fluids.control_valve.
Cv_char_linear
(opening)¶
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fluids.control_valve.
Cv_char_quick_opening
(opening)¶
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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
- Psatfloat
Saturation pressure of the liquid at inlet temperature [Pa]
- Pcfloat
Critical pressure of the liquid [Pa]
- Returns
- FFfloat
Liquid critical pressure ratio factor [-]
References
- 1
IEC 60534-2-1 / ISA-75.01.01-2007
Examples
From [1], matching example.
>>> FF_critical_pressure_ratio_l(70100.0, 22120000.0) 0.9442375225233299
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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
- FLfloat
Liquid pressure recovery factor of a control valve without attached fittings []
- Cfloat
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
- dfloat
Diameter of the valve [m]
- Revfloat
Valve reynolds number [-]
- full_trimbool
Whether or not the valve has full trim
- Returns
- FRfloat
Reynolds number factor for laminar or transitional flow []
References
- 1
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
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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
- nufloat
Kinematic viscosity, [m^2/s]
- Qfloat
Volumetric flow rate of the fluid [m^3/s]
- D1float
Diameter of the pipe before the valve [m]
- FLfloat, optional
Liquid pressure recovery factor of a control valve without attached fittings []
- Fdfloat
Valve style modifier [-]
- Cfloat
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
- Returns
- Revfloat
Valve reynolds number [-]
References
- 1
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
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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
- P1float
Absolute pressure upstream of the valve [Pa]
- P2float
Absolute pressure downstream of the valve [Pa]
- Psatfloat
Saturation pressure of the liquid at inlet temperature [Pa]
- Returns
- sigmafloat
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
- 1
ISA. “RP75.23 Considerations for Evaluating Control Valve Cavitation.” 1995.
Examples
>>> cavitation_index(1E6, 8E5, 2E5) 4.0
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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
- xTfloat, optional
Pressure difference ratio factor of a valve without fittings at choked flow [-]
- gammafloat
Specific heat capacity ratio [-]
- P1float, optional
Absolute pressure upstream of the valve [Pa]
- P2float, optional
Absolute pressure downstream of the valve [Pa]
- Returns
- P_chokefloat
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
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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
- Psatfloat
Saturation pressure of the liquid at inlet temperature [Pa]
- Pcfloat
Critical pressure of the liquid [Pa]
- FLfloat, optional
Liquid pressure recovery factor of a control valve without attached fittings [-]
- P1float, optional
Absolute pressure upstream of the valve [Pa]
- P2float, optional
Absolute pressure downstream of the valve [Pa]
- dispbool, optional
Whether or not to raise an exception on flow reversal, [-]
- Returns
- P_chokefloat
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
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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) [1].
- Parameters
- mfloat
Mass flow rate of gas through the control valve, [kg/s]
- P1float
Inlet pressure of the gas before valves and reducers [Pa]
- P2float
Outlet pressure of the gas after valves and reducers [Pa]
- T1float
Inlet gas temperature, [K]
- rhofloat
Density of the gas at the inlet [kg/m^3]
- gammafloat
Specific heat capacity ratio [-]
- MWfloat
Molecular weight of the gas [g/mol]
- Kvfloat
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
- dfloat
Diameter of the valve [m]
- Difloat
Internal diameter of the pipe before and after the valve [m]
- t_pipefloat
Wall thickness of the pipe after the valve, [m]
- Fdfloat
Valve style modifier (0.1 to 1; varies tremendously depending on the type of valve and position; do not use the default at all!) [-]
- FLfloat
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!) [-]
- FLPfloat, optional
Combined liquid pressure recovery factor with piping geometry factor, for a control valve with attached fittings [-]
- FPfloat, optional
Piping geometry factor [-]
- rho_pipefloat, optional
Density of the pipe wall material at flowing conditions, [kg/m^3]
- c_pipefloat, optional
Speed of sound of the pipe wall material at flowing conditions, [m/s]
- P_airfloat, optional
Pressure of the air surrounding the valve and pipe wall, [Pa]
- rho_airfloat, optional
Density of the air surrounding the valve and pipe wall, [kg/m^3]
- c_airfloat, optional
Speed of sound of the air surrounding the valve and pipe wall, [m/s]
- Anfloat, optional
Valve correction factor for acoustic efficiency
- Stpfloat, optional
Strouhal number at the peak fp; between 0.1 and 0.3 typically, [-]
- T2float, optional
Outlet gas temperature; assumed T1 if not provided (a PH flash should be used to obtain this if possible), [K]
- betafloat, optional
Valve outlet / expander inlet contraction coefficient, [-]
- Returns
- LpAe1mfloat
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 [1]. This takes on the order of 100 us to compute. For values of An, see [1].
This model was checked against six examples in [1]; 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
- 1(1,2,3,4)
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
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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) [1].
- Parameters
- mfloat
Mass flow rate of liquid through the control valve, [kg/s]
- P1float
Inlet pressure of the fluid before valves and reducers [Pa]
- P2float
Outlet pressure of the fluid after valves and reducers [Pa]
- Psatfloat
Saturation pressure of the fluid at inlet temperature [Pa]
- rhofloat
Density of the liquid at the inlet [kg/m^3]
- cfloat
Speed of sound of the liquid at the inlet conditions [m/s]
- Kvfloat
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
- dfloat
Diameter of the valve [m]
- Difloat
Internal diameter of the pipe before and after the valve [m]
- FLfloat, 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) [-]
- Fdfloat, optional
Valve style modifier [-]
- t_pipefloat
Wall thickness of the pipe after the valve, [m]
- rho_pipefloat, optional
Density of the pipe wall material at flowing conditions, [kg/m^3]
- c_pipefloat, optional
Speed of sound of the pipe wall material at flowing conditions, [m/s]
- rho_airfloat, optional
Density of the air surrounding the valve and pipe wall, [kg/m^3]
- c_airfloat, optional
Speed of sound of the air surrounding the valve and pipe wall, [m/s]
- xFzfloat, optional
If specified, this value xFz is used instead of estimated; the calculation is sensitive to this value, [-]
- Anfloat, optional
Valve correction factor for acoustic efficiency
- Returns
- LpAe1mfloat
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 [1]. 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 [1]; 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 [1]; they match to all given decimals.
A formula is given in [1] 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
- 1(1,2,3,4,5)
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
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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_coefficientfloat
Value of the flow coefficient to be converted, expressed in the original scale.
- old_scalestr
String specifying the original scale; one of ‘Av’, ‘Cv’, or ‘Kv’, [-]
- new_scalestr
String specifying the new scale; one of ‘Av’, ‘Cv’, or ‘Kv’, [-]
- Returns
- converted_flow_coefficientfloat
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
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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
- xfloat
Differential pressure over inlet pressure, [-]
- Fgammafloat
Specific heat ratio factor [-]
- xTfloat, optional
Pressure difference ratio factor of a valve without fittings at choked flow [-]
- xTPfloat
Pressure difference ratio factor of a valve with fittings at choked flow [-]
- Returns
- chokedbool
Whether or not the flow is choked [-]
References
- 1
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
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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
- dPfloat
Differential pressure across the valve, with reducer/expanders [Pa]
- P1float
Pressure of the fluid before the valve and reducers/expanders [Pa]
- Psatfloat
Saturation pressure of the fluid at inlet temperature [Pa]
- FFfloat
Liquid critical pressure ratio factor [-]
- FLfloat, optional
Liquid pressure recovery factor of a control valve without attached fittings [-]
- FLPfloat, optional
Combined liquid pressure recovery factor with piping geometry factor, for a control valve with attached fittings [-]
- FPfloat, optional
Piping geometry factor [-]
- Returns
- chokedbool
Whether or not the flow is choked [-]
References
- 1
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
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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
- dfloat
Diameter of the valve [m]
- D1float
Diameter of the pipe before the valve [m]
- D2float
Diameter of the pipe after the valve [m]
- Returns
- lossfloat
Sum of the four loss coefficients [-]
References
- 1
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
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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 [1]. Note the inlet gas flow conditions.
- Parameters
- Tfloat
Temperature of the gas at the inlet [K]
- MWfloat
Molecular weight of the gas [g/mol]
- mufloat
Viscosity of the fluid at inlet conditions [Pa*s]
- gammafloat
Specific heat capacity ratio [-]
- Zfloat
Compressibility factor at inlet conditions, [-]
- P1float
Inlet pressure of the gas before valves and reducers [Pa]
- P2float
Outlet pressure of the gas after valves and reducers [Pa]
- Qfloat
Volumetric flow rate of the gas at 273.15 K and 1 atm specifically [m^3/s]
- D1float, optional
Diameter of the pipe before the valve [m]
- D2float, optional
Diameter of the pipe after the valve [m]
- dfloat, optional
Diameter of the valve [m]
- FLfloat, 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!) []
- Fdfloat, 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!) []
- xTfloat, 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_chokedbool, optional
Overrides the automatic transition into the choked regime if this is False and returns as if choked flow does not exist
- allow_laminarbool, optional
Overrides the automatic transition into the laminar regime if this is False and returns as if laminar flow does not exist
- full_outputbool, 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
- Kvfloat
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 [1], 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 [1], 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
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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 [1].
- Parameters
- rhofloat
Density of the liquid at the inlet [kg/m^3]
- Psatfloat
Saturation pressure of the fluid at inlet temperature [Pa]
- Pcfloat
Critical pressure of the fluid [Pa]
- mufloat
Viscosity of the fluid [Pa*s]
- P1float
Inlet pressure of the fluid before valves and reducers [Pa]
- P2float
Outlet pressure of the fluid after valves and reducers [Pa]
- Qfloat
Volumetric flow rate of the fluid [m^3/s]
- D1float, optional
Diameter of the pipe before the valve [m]
- D2float, optional
Diameter of the pipe after the valve [m]
- dfloat, optional
Diameter of the valve [m]
- FLfloat, 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!) []
- Fdfloat, 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_chokedbool, optional
Overrides the automatic transition into the choked regime if this is False and returns as if choked flow does not exist
- allow_laminarbool, optional
Overrides the automatic transition into the laminar regime if this is False and returns as if laminar flow does not exist
- full_outputbool, 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
- Kvfloat
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 [1], 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 [1], 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