def Cv_to_Kv(Cv):
    """Convert valve flow coefficient from imperial to common metric units.

    .. math::
        K_v = C_v/1.156

    Parameters
    ----------
    Cv : float
        Imperial Cv valve flow coefficient (flow rate of water at a pressure   
        drop of 1 psi) [gallons/minute]

    Returns
    -------
    Kv : float
        Metric Kv valve flow coefficient (flow rate of water at a pressure drop  
        of 1 bar) [m^3/hr]

    Notes
    -----
    Kv = 0.865 Cv is in the IEC standard 60534-2-1.
    It has also been said that Cv = 1.17Kv; this is wrong by current standards.

    The conversion factor does not depend on the density of the fluid or the
    diameter of the valve. It is calculated with the definition of a US gallon
    as 231 cubic inches, and a psi as a pound-force per square inch.

    The exact conversion coefficient between Kv to Cv is 1.1560992283536566;
    it is rounded in the formula above.

    Examples
    --------
    >>> Cv_to_Kv(2.312)
    1.9998283393826013

    References
    ----------
    .. [1] ISA-75.01.01-2007 (60534-2-1 Mod) Draft
    """
    return Cv / 1.1560992283536566
