Silotank range of Bypass Separators are used where the risk of a large spillage and heavy rainfall occurring at the same time is small and it is deemed that full treatment of very high flows is not necessary. Bypass separators fully treat all flows, for the area served, generated by rainfall events of up to 6.5 mm/hr i.e. 99% of all rainfall events.
Common applications for Bypass Separators are
- Surface Car Parks
- Lightly contaminated commercial areas
Each bypass separator design includes the necessary volume requirements to meet the recommendations laid down in Pollution Prevention Guidelines PPG3. These include:
- Oil Storage Volume (V = NSB x 15 litres)
- Silt Storage Capacity (C = NSB x 100 litres)
- Coalescing Filter
The nominal size of a bypass separator that is required for a catchment area (A) is obtained using the following formula:
NSB = 0.0018(A) m2
The flows generated by higher rainfalls will pass through the weir chamber and bypass the main separation chamber. Class 1 separators are designed to achieve a discharge concentration of less than 5mg/litre of oil under standard test conditions.