SQ_EDGE_SCREEN

Computes the pressure-loss coefficient K for square-edge wire screens, bar screens, or perforated plates based on open-area fraction.

The correlation is implemented through linear interpolation of empirical tabulated values, yielding a monotonic increase in loss as openness decreases.

The resulting coefficient represents head loss relative to the approach velocity upstream of the screen.

Excel Usage

=SQ_EDGE_SCREEN(alpha)

• alpha (float, required): Fraction of screen open to flow, [-]

Returns (float): Loss coefficient K, [-], or error message (str) if input is invalid.

Example 1: Square-edge screen at very high openness alpha 0.99

Inputs:

alpha
0.99

Excel formula:

=SQ_EDGE_SCREEN(0.99)

Expected output:

0.008

Example 2: Square-edge screen at moderate openness alpha 0.5

Inputs:

alpha
0.5

Excel formula:

=SQ_EDGE_SCREEN(0.5)

Expected output:

3.8

Example 3: Square-edge screen at low openness alpha 0.2

Inputs:

alpha
0.2

Excel formula:

=SQ_EDGE_SCREEN(0.2)

Expected output:

52

Example 4: Square-edge screen at typical openness alpha 0.7

Inputs:

alpha
0.7

Excel formula:

=SQ_EDGE_SCREEN(0.7)

Expected output:

1.1

Python Code

Show Code

from fluids.filters import square_edge_screen as fluids_square_edge_screen

def sq_edge_screen(alpha):
    """
    Calculate the loss coefficient for a square edged wire screen, bar screen, or perforated plate.

    See: https://fluids.readthedocs.io/fluids.filters.html#fluids.filters.square_edge_screen

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

    Args:
        alpha (float): Fraction of screen open to flow, [-]

    Returns:
        float: Loss coefficient K, [-], or error message (str) if input is invalid.
    """
    try:
      # Validate and convert alpha
      try:
        alpha = float(alpha)
      except (ValueError, TypeError):
        return "Error: alpha must be a number."

      # Validate alpha range
      if alpha <= 0 or alpha > 1:
        return "Error: alpha must be between 0 and 1."

      result = fluids_square_edge_screen(alpha=alpha)
      if result != result or result in (float('inf'), float('-inf')):
        return "Error: Result is not finite."
      return float(result)
    except Exception as e:
      return f"Error: {str(e)}"

Online Calculator

alpha *

Fraction of screen open to flow, [-]