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          Using an iterative program found in the Fluids Functions (ND.Manifold) and the available pipe sizes, the nominal diameter of the manifold 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.

{latex}
\large
$$
HL_{SedLaunderEst} = (K{8 \over {g\pi ^2 }}{{Q^2 } \over {D^4 }} + {8 \over {g\pi ^2 }}{{L_{SedLaunderEst} Q_{Sed}^2 } \over {ND_{SedLaunderEst}^5 }})({1 \over 3} + {1 \over {2N_{SedLaunderOrifices} }} + {1 \over {6N_{SedLaunderOrifices}^2 }})
$$
{latex}

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

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           To re-fill the sedimentation tank with clean water from the exit channel, a uniquely designed control piece is fitted into the launder coupling. The launder is removed from its place when the tank is drained. Then, a control piece consisting of a short pipe covered by a cap with a single orifice is fitted in its place. The size of this orifice is calculated so that the flow rate of water into the empty sedimentation tank is not higher than the flow rate of water out of the other sedimentation tanks so that the plant water level does not drop.

{latex}
\large
$$
A_{Orifice} = {Q_{Sed} \over (Pi_{VenaContractaOrifice})\sqrt{2g(H_{LaunderCap})}}
$$
{latex}

{latex}
\large
$$
H_{LaunderCap} = {H_{Sed} - H_{ExitChannel} + HW_{ExitChannel}}
$$
{latex}

          Once the tank is refilled, the control piece is removed and the launder replaced.

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