IAPWS92_PSAT

This function evaluates the saturation pressure of water from temperature using the IAPWS-92 formulation.

The saturation-pressure model is of the form:

P_{sat} = P_c \exp\left(\frac{T_c}{T} \sum_i a_i\tau^{n_i}\right)

where \tau = 1 - T/T_c, and the coefficients are defined by the IAPWS-92 standard for vapor-pressure calculations.

Excel Usage

=IAPWS92_PSAT(temperature)

• temperature (float, required): Temperature for saturation-pressure evaluation (K).

Returns (float): Saturation vapor pressure of water (Pa).

Example 1: Saturation pressure near boiling point

Inputs:

temperature
373.15

Excel formula:

=IAPWS92_PSAT(373.15)

Expected output:

101418

Example 2: Saturation pressure at moderate temperature

Inputs:

temperature
325

Excel formula:

=IAPWS92_PSAT(325)

Expected output:

13532.1

Example 3: Saturation pressure at elevated temperature

Inputs:

temperature
450

Excel formula:

=IAPWS92_PSAT(450)

Expected output:

932203

Example 4: Saturation pressure at low positive temperature

Inputs:

temperature
280

Excel formula:

=IAPWS92_PSAT(280)

Expected output:

991.759

Python Code

Show Code

from chemicals.air import iapws92_Psat as chemicals_iapws92_psat

def iapws92_psat(temperature):
    """
    Compute saturation vapor pressure using the IAPWS-92 correlation.

    See: https://chemicals.readthedocs.io/chemicals.air.html

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

    Args:
        temperature (float): Temperature for saturation-pressure evaluation (K).

    Returns:
        float: Saturation vapor pressure of water (Pa).
    """
    try:
        return chemicals_iapws92_psat(temperature)
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

temperature *

Temperature for saturation-pressure evaluation (K).