CV_CAV_INDEX

Overview

Calculates the cavitation index of a control valve.

Excel Usage

=CV_CAV_INDEX(p_inlet, p_outlet, p_sat)

• p_inlet (float, required): Inlet absolute pressure (Pa)
• p_outlet (float, required): Outlet absolute pressure (Pa)
• p_sat (float, required): Saturation absolute pressure (Pa)

Returns (float): Cavitation index sigma (-)

Examples

Example 1: Documentation example

Inputs:

p_inlet	p_outlet	p_sat
1000000	800000	200000

Excel formula:

=CV_CAV_INDEX(1000000, 800000, 200000)

Expected output:

4

Example 2: Low outlet pressure

Inputs:

p_inlet	p_outlet	p_sat
1000000	100000	50000

Excel formula:

=CV_CAV_INDEX(1000000, 100000, 50000)

Expected output:

1.05556

Example 3: Near saturation

Inputs:

p_inlet	p_outlet	p_sat
1000000	500000	990000

Excel formula:

=CV_CAV_INDEX(1000000, 500000, 990000)

Expected output:

0.02

Example 4: High index (low delta P)

Inputs:

p_inlet	p_outlet	p_sat
1000000	990000	100000

Excel formula:

=CV_CAV_INDEX(1000000, 990000, 100000)

Expected output:

90

Python Code

import micropip
await micropip.install(["fluids"])
from fluids.control_valve import cavitation_index

def cv_cav_index(p_inlet, p_outlet, p_sat):
    """
    Calculates the cavitation index of a control valve.

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

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

    Args:
        p_inlet (float): Inlet absolute pressure (Pa)
        p_outlet (float): Outlet absolute pressure (Pa)
        p_sat (float): Saturation absolute pressure (Pa)

    Returns:
        float: Cavitation index sigma (-)
    """
    if p_inlet <= p_outlet:
        return "Error: Inlet pressure must be greater than outlet pressure."
    if p_inlet <= p_sat:
        return "Error: Inlet pressure must be greater than saturation pressure."

    return float(cavitation_index(P1=p_inlet, P2=p_outlet, Psat=p_sat))

Online Calculator