CV_CONVERT_COEFF

Converts a valve flow coefficient between the supported scales Kv, Cv, and Av.

The conversion applies fixed scale relationships so the same physical valve capacity is preserved across unit systems.

This is useful when moving between IEC-style K_v, US-style C_v, and SI-area-style A_v specifications.

Excel Usage

=CV_CONVERT_COEFF(coeff, old_scale, new_scale)
  • coeff (float, required): Flow coefficient value to convert.
  • old_scale (str, required): Original scale (e.g., Kv, Cv, Av).
  • new_scale (str, required): Target scale (e.g., Kv, Cv, Av).

Returns (float): Converted flow coefficient.

Example 1: Kv to Cv

Inputs:

coeff old_scale new_scale
10 Kv Cv

Excel formula:

=CV_CONVERT_COEFF(10, "Kv", "Cv")

Expected output:

11.561

Example 2: Cv to Kv

Inputs:

coeff old_scale new_scale
11.56 Cv Kv

Excel formula:

=CV_CONVERT_COEFF(11.56, "Cv", "Kv")

Expected output:

9.99914

Example 3: Kv to Av

Inputs:

coeff old_scale new_scale
10 Kv Av

Excel formula:

=CV_CONVERT_COEFF(10, "Kv", "Av")

Expected output:

0.000277653

Example 4: Same scale

Inputs:

coeff old_scale new_scale
50 Cv Cv

Excel formula:

=CV_CONVERT_COEFF(50, "Cv", "Cv")

Expected output:

50

Python Code

Show Code 
from fluids.control_valve import convert_flow_coefficient

def cv_convert_coeff(coeff, old_scale, new_scale):
    """
    Converts between different flow coefficient scales (Kv, Cv, Av).

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

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

    Args:
        coeff (float): Flow coefficient value to convert.
        old_scale (str): Original scale (e.g., Kv, Cv, Av). Valid options: Kv (metric), Cv (US), Av (SI).
        new_scale (str): Target scale (e.g., Kv, Cv, Av). Valid options: Kv (metric), Cv (US), Av (SI).

    Returns:
        float: Converted flow coefficient.
    """
    try:
      coeff = float(coeff)

      if coeff < 0:
        return "Error: Flow coefficient cannot be negative."

      return float(convert_flow_coefficient(coeff, old_scale, new_scale))
    except Exception as e:
      return f"Error: {str(e)}"

Online Calculator

Flow coefficient value to convert.
Original scale (e.g., Kv, Cv, Av).
Target scale (e.g., Kv, Cv, Av).