# Control valve sizing and rating (fluids.control_valve)¶

fluids.control_valve.size_control_valve_l(rho, Psat, Pc, mu, P1, P2, Q, D1, D2, d, FL, Fd)[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 [R125133].

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 Diameter of the pipe before the valve [m] D2 : float Diameter of the pipe after the valve [m] d : float Diameter of the valve [m] FL : float 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]

References

 [R125133] (1, 2, 3, 4) IEC 60534-2-1 / ISA-75.01.01-2007

Examples

From [R125133], 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 [R125133], 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, D2, d, FL, Fd, xT)[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 [R126134]. 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 Diameter of the pipe before the valve [m] D2 : float Diameter of the pipe after the valve [m] d : float Diameter of the valve [m] FL : float Liquid pressure recovery factor of a control valve without attached fittings [-] Fd : float Valve style modifier [-] xT : float Pressure difference ratio factor of a valve without fittings at choked flow [-] C : float Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]

References

 [R126134] (1, 2, 3, 4) IEC 60534-2-1 / ISA-75.01.01-2007

Examples

From [R126134], 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 [R126134], 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] 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

 [R127135] 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] FF : float Liquid critical pressure ratio factor [-]

References

 [R128136] (1, 2) IEC 60534-2-1 / ISA-75.01.01-2007

Examples

From [R128136], 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.

\begin{align}\begin{aligned}\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})\end{aligned}\end{align}
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 [-] choked : bool Whether or not the flow is choked [-]

References

 [R129137] 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.

\begin{align}\begin{aligned}x \ge F_\gamma x_T\\x \ge F_\gamma x_{TP}\end{aligned}\end{align}
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 [-] choked : bool Whether or not the flow is choked [-]

References

 [R130138] 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] Rev : float Valve reynolds number [-]

References

 [R131139] 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.

\begin{align}\begin{aligned}\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\end{aligned}\end{align}
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] loss : float Sum of the four loss coefficients [-]

References

 [R132140] 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:

\begin{align}\begin{aligned}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})\end{aligned}\end{align}

Otherwise :

\begin{align}\begin{aligned}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})\end{aligned}\end{align}
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 FR : float Reynolds number factor for laminar or transitional flow []

References

 [R133141] 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