Bottom distributor (6 beams) for 30″
The lower drainage and distribution systems are a system of pipes with slots, the width of which should be 0.1 mm less than the size of the smallest fraction of the filter load. The total area of the slots should be in the range of 1.5 – 2% of the filter area.
The lower drainage and distribution systems of quick filters must meet the following requirements
- uniformity of distribution of rinse water over the filter area;
- uniformity of filtered water collection from the filter area;
- sufficient mechanical strength;
- slots not clogging during the operating cycle and rinsing.
To protect the lower drainage and distribution system from the products of the destruction of the load, it is usually “closed” with a layer of special gravel backfill, called a “gravel bed”. The height of the gravel bed usually exceeds the top of the drainage and distribution system by 5 centimeters or more.
The presence of a gravel bed also contributes to a more even distribution of the water flow during backwash and prevents the formation of so-called “water potholes”.