IS_CHOKED_GAS

Evaluates whether a gas valve operating point is choked (critical) using IEC 60534 inequalities.

Choking is detected when either condition is met, depending on provided factor:

x \ge F_\gamma x_T

x \ge F_\gamma x_{TP}

The function returns True for choked flow and False otherwise.

Excel Usage

=IS_CHOKED_GAS(x, Fgamma, xT, xTP)

x (float, required): Differential pressure ratio (dP/P1) [-]
Fgamma (float, required): Specific heat ratio factor [-]
xT (float, optional, default: null): Pressure difference ratio factor of a valve without fittings [-]
xTP (float, optional, default: null): Pressure difference ratio factor of a valve with fittings [-]

Returns (bool): True if flow is choked (critical), False otherwise.

Example 1: Non-choked flow example

Inputs:

x	Fgamma	xT
0.544	0.929	0.6

Excel formula:

=IS_CHOKED_GAS(0.544, 0.929, 0.6)

Expected output:

false

Example 2: Choked flow example

Inputs:

x	Fgamma	xT
0.6	0.929	0.6

Excel formula:

=IS_CHOKED_GAS(0.6, 0.929, 0.6)

Expected output:

true

Example 3: Non-choked with fittings

Inputs:

x	Fgamma	xTP
0.544	0.929	0.625

Excel formula:

=IS_CHOKED_GAS(0.544, 0.929, 0.625)

Expected output:

false

Example 4: Choked with fittings

Inputs:

x	Fgamma	xTP
0.8	0.929	0.625

Excel formula:

=IS_CHOKED_GAS(0.8, 0.929, 0.625)

Expected output:

true

Python Code

Show Code

from fluids.control_valve import is_choked_turbulent_g as fluids_is_choked

def is_choked_gas(x, Fgamma, xT=None, xTP=None):
    """
    Determines if a gas flow in a control valve is choked (critical) or not according to IEC 60534.

    See: https://fluids.readthedocs.io/fluids.control_valve.html#fluids.control_valve.is_choked_turbulent_g

    This example function is provided as-is without any representation of accuracy.

    Args:
        x (float): Differential pressure ratio (dP/P1) [-]
        Fgamma (float): Specific heat ratio factor [-]
        xT (float, optional): Pressure difference ratio factor of a valve without fittings [-] Default is None.
        xTP (float, optional): Pressure difference ratio factor of a valve with fittings [-] Default is None.

    Returns:
        bool: True if flow is choked (critical), False otherwise.
    """
    try:
      x = float(x)
      Fgamma = float(Fgamma)

      if xT is not None:
        xT = float(xT)
      if xTP is not None:
        xTP = float(xTP)

      if x < 0:
        return "Error: Differential pressure ratio must be non-negative."
      if Fgamma <= 0:
        return "Error: Fgamma must be positive."

      if xT is None and xTP is None:
        return "Error: Either xT or xTP must be provided."

      return fluids_is_choked(x=x, Fgamma=Fgamma, xT=xT, xTP=xTP)
    except Exception as e:
      return f"Error: {str(e)}"

Online Calculator

x *

Differential pressure ratio (dP/P1) [-]

Fgamma *

Specific heat ratio factor [-]

Pressure difference ratio factor of a valve without fittings [-]

xTP

Pressure difference ratio factor of a valve with fittings [-]