Armfield Instruction Manual
32
The space in the tank between the perforated metal sheets is then filled with sand to
a depth of about 450mm. The overflows are set with their tops about 25mm above
sand level, before water is poured slowly into the space around the upstream
overflow.
After steady flow conditions have been achieved, dye is introduced in the usual
manner at different points along the sand surface and, also along the edge of the
upstream membrane.