Control valve sizing and rating (fluids.control_valve)

This module contains equations for modeling control valves subject to gas or liquid flow.

For reporting bugs, adding feature requests, or submitting pull requests, please use the GitHub issue tracker or contact the author at Caleb.Andrew.Bell@gmail.com.

Sizing Functions

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)

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

1(1,2,3)

IEC 60534-2-1 / ISA-75.01.01-2007

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

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)

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.

When this model does not converge, the result is normally because of the specified delta P being less than that caused by the piping diameter changes.

References

1(1,2,3)

IEC 60534-2-1 / ISA-75.01.01-2007

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)
72.5866454539105

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

Intermediary Sizing Calculations

fluids.control_valve.FF_critical_pressure_ratio_l(Psat, Pc)

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

fluids.control_valve.is_choked_turbulent_l(dP, P1, Psat, FF, FL=None, FLP=None, FP=None)

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

fluids.control_valve.is_choked_turbulent_g(x, Fgamma, xT=None, xTP=None)

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

fluids.control_valve.Reynolds_valve(nu, Q, D1, FL, Fd, C)

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

fluids.control_valve.Reynolds_factor(FL, C, d, Rev, full_trim=True)

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

fluids.control_valve.loss_coefficient_piping(d, D1=None, D2=None)

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

fluids.control_valve.control_valve_choke_P_l(Psat, Pc, FL, P1=None, P2=None, disp=True)

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

fluids.control_valve.control_valve_choke_P_g(xT, gamma, P1=None, P2=None)

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(1.0, 1.3, 1E5)
7142.857142857143
>>> control_valve_choke_P_g(1.0, 1.3, P2=7142.857142857143)
100000.0

fluids.control_valve.convert_flow_coefficient(flow_coefficient, old_scale, new_scale)

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

fluids.control_valve.cavitation_index(P1, P2, Psat)

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

Representative Control Valve Curves

fluids.control_valve.Cv_char_linear(opening)

fluids.control_valve.Cv_char_quick_opening(opening)

fluids.control_valve.Cv_char_equal_percentage(opening)

Noise Generated by Control Valves

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)

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), [dB]

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 global 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)
81.58200097996

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)

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), [dB]

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