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, nonNewtonian fluids, or liquidsolid conveyance systems. For details of the calculations, consult [R123131].
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 []
Returns: C : float
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
References
[R123131] (1, 2, 3, 4) IEC 6053421 / ISA75.01.012007 Examples
From [R123131], matching example 1 for a globe, parabolic plug, flowtoopen valve.
>>> size_control_valve_l(rho=965.4, Psat=70.1E3, Pc=22120E3, mu=3.1472E4, ... 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 [R123131], matching example 2 for a ball, segmented ball, flowtoopen valve.
>>> size_control_valve_l(rho=965.4, Psat=70.1E3, Pc=22120E3, mu=3.1472E4, ... 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 [R124132]. 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 []
Returns: C : float
Metric Kv valve flow coefficient (flow rate of water at a pressure drop of 1 bar) [m^3/hr]
References
[R124132] (1, 2, 3, 4) IEC 6053421 / ISA75.01.012007 Examples
From [R124132], matching example 3 for nonchoked gas flow with attached fittings and a rotary, eccentric plug, flowtoopen control valve:
>>> size_control_valve_g(T=433., MW=44.01, mu=1.4665E4, 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 [R124132], 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=5.625E5, 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
[R125133] 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
[R126134] (1, 2) IEC 6053421 / ISA75.01.012007 Examples
From [R126134], 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 []
Returns: choked : bool
Whether or not the flow is choked []
References
[R127135] IEC 6053421 / ISA75.01.012007 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 []
Returns: choked : bool
Whether or not the flow is choked []
References
[R128136] IEC 6053421 / ISA75.01.012007 Examples
Example 3, compressible flow, nonchoked 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
[R129137] IEC 6053421 / ISA75.01.012007 Examples
>>> Reynolds_valve(3.26e07, 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]
Returns: loss : float
Sum of the four loss coefficients []
References
[R130138] IEC 6053421 / ISA75.01.012007 Examples
In example 3, nonchoked 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
Returns: FR : float
Reynolds number factor for laminar or transitional flow []
References
[R131139] IEC 6053421 / ISA75.01.012007 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