Thin mechanized step screen

Input data

Flow

Width (b)

Trashrack width (W)

Distance between trashracks (d)

Downflow level (y)

Inclination (º)

β - Kirschmer

Output data

Upflow level

Upflow velocity

Energy

Velocity between bars

Head loss

Upflow level at 50%

Upflow velocity at 50%

Velocity between bars at 50%

Upflow energy at 50%

Head loss at 50%

Description

The thin mechanized step screen is designed for debris removal in hydraulic flows, using calculation methods based on variables like flow rate and specific channel geometries.

Image

Downflow calculation:

Parameter
Standard Units
Description
Flow
m³/s
Volume of water passing through the section
Width (b)
m
Channel width
Trashrack width (W)
m
Thickness of the trashrack bar
Distance between trashracks (d)
m
Spacing between the bars
Downflow level (y)
m
Water level at the downstream side
Inclination (º)
º
Angle of the bars relative to the flow
β - Kirschmer
-
Kirschmer coefficient for calculation

Calculated results:

Parameter
Standard Units
Description
Upflow level (ym)
m
Water level at the upstream side
Upflow velocity (Um)
m/s
Velocity of flow at the upstream side
Energy (Em)
J
Energy associated with the upstream flow
Velocity between bars (Ubb)
m/s
Flow velocity between the trashrack bars
Head loss (Hl)
m
Pressure drop or head loss
Upflow level at 50% (ym50)
m
Upstream level calculated with 50% of the flow
Upflow velocity at 50% (Um50)
m/s
Upstream velocity at 50% of the flow
Velocity between bars at 50% (Ubb50)
m/s
Velocity between bars with 50% of the flow
Upflow energy at 50% (Em50)
J
Energy with 50% of the flow
Head loss at 50% (Hl50)
m
Head loss with 50% of the flow
Flow output (Qout)
m³/s
Volume of water exiting the system

References

  • WEF, ASCE, EWRI (2010). Design of municipal wastewater treatment plants. Volume 2: liquid treatment processes. New York, McGraw Hill.