IAPWS95_PSAT

This function computes the saturation vapor pressure of water from temperature using high-accuracy IAPWS-95 fit equations. It is intended for smooth and precise saturation-line evaluation.

The saturation mapping is:

P_{sat} = f(T)

where T is temperature and P_{sat} is saturation pressure.

Excel Usage

=IAPWS95_PSAT(T)

• T (float, required): Water saturation temperature (K).

Returns (float): Saturation vapor pressure of water at the specified temperature (Pa).

Example 1: Saturation pressure at moderate temperature

Inputs:

T
400

Excel formula:

=IAPWS95_PSAT(400)

Expected output:

245769

Example 2: Saturation pressure near low fit range

Inputs:

T
240

Excel formula:

=IAPWS95_PSAT(240)

Expected output:

37.6195

Example 3: Saturation pressure at elevated temperature

Inputs:

T
500

Excel formula:

=IAPWS95_PSAT(500)

Expected output:

2639200

Example 4: Saturation pressure near critical point

Inputs:

T
646

Excel formula:

=IAPWS95_PSAT(646)

Expected output:

21774900

Python Code

Show Code

from chemicals.iapws import iapws95_Psat as chemicals_iapws95_psat

def iapws95_psat(T):
    """
    Compute saturation pressure from temperature using IAPWS-95 polynomial fits.

    See: https://chemicals.readthedocs.io/chemicals.iapws.html#chemicals.iapws.iapws95_Psat

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

    Args:
        T (float): Water saturation temperature (K).

    Returns:
        float: Saturation vapor pressure of water at the specified temperature (Pa).
    """
    try:
        return chemicals_iapws95_psat(T)
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

T *

Water saturation temperature (K).