Hydraulic performance

The slot unit can be considered as a pipe for the purposes of the hydraulic calculations and be dimensioned according to Prandtl-Colebrook. Run-off rates for the respective longfall are given in the diagram. 

The maximum distance between the inlet shafts/gullys is calculated from the run-off rate for the given channel gradient divided by the lateral inflow per metre length. 

The water inlet area of all profiles, based on the standard effective length 4.00 m with continuous slot, is approx. 25,500 mm2/m, for channels with an intermittent slot and profiles 30/20, 30R, 30/40 and 20/40 it is approx. 17,500 mm2/m and for profiles 20R, 20/30 and 25R it is approx. 14,900 mm2/m.