Launder Design Program

This program is used to design the manifold that will be used for transporting water out of the sedimentation tank to the exit channel. The launder will be located between the top of the lamella and the surface of the water in the sedimentation tank. The orifices will be at the center of the launders for water intake. The Launder program uses equations found in the fluids functions and sedimentation programs.

Launder Design Program Algorithm

Launder Program Inputs
Launder Program Outputs
Launder AutoCAD Drawing Program

Algorithm

Given the maximum flow rate through the treatment plant, and the number of sedimentation tanks in the plant, the flow rate for each sedimentation tank is equally divided between the number of sedimentation tanks. The length of the manifold section of the launder is the same as the length of the tank, minus the width of the entrance tank and the wall thickness.

To determine the number of orifices in the launder, the length of the established manifold is divided by the specified orifice spacing, found in the Design Assumptions. Note that there are two rows of orifices on a single manifold. This number is rounded down to the nearest whole number.

There will be 2 sedimentation launder pipes within each sedimentation tank, as defined in the the Design Assumptions program. From that number the flow rate through each orifice is calculated.

Using an iterative program found in the Fluids Functions (ND.Manifold) and the available pipe sizes, the nominal diameter is determined and defined as ND.SedLaunderEst. This equation is a function of different parameters established in the Design Assumptions.
The total head loss in the launder is then calculated using the HL.Manifold equation found in the Fluids Functions. This equation is defined below with the given inputs and a minor head loss of 0.

Next, the head loss through the orifice is the given head loss, HL.SedLaunderBod, minus the calculated head loss through the whole launder.
Finally, the diameter of the orifice holes is calculated using the D.Circle equation from the fluids functions. This number is roundest to the nearest available drill size. Written out, the equation is as follows: