Bypass Separator

NSBP Range


Bypass separators are used when it is considered an acceptable risk not to provide full treatment, for very high flows, and are used, for example, where the risk of a large spillage and heavy rainfall occurring at the same time is small, e.g.
    • Surface car parks
    • Roadways
    • Lightly contaminated commercial areas


Kingspan Environmental Bypass_Separator_NSBP_Rangewere one of the first UK manufacturers to have separators tested to EN 858-1. Kingspan Environmental have now added the NSBP bypass range to their portfolio of certified and tested models. The NSBP number denotes the maximum flow
at which the separator treats liquids. The British Standards Institute (BSI) tested the required range of Klargester full retention separators and certified their performance in relation to their flow and process performance assessing the effluent qualities to the
requirements of BS EN 858-1. Klargester bypass separator designs follow the parameters determined during the testing of the required range of bypass separators.

Each bypass separator design includes the necessary volume requirements for:

    • Oil separation capacity
    • Oil storage volume
    • Silt storage capacity
    • Coalescer
The unit is designed to treat 10% of peak flow. The calculated drainage areas served by each separator are indicated according to the formula given by PPG3 NSB = 0.0018A(m2).  Flows generated by higher rainfall rates will pass through part of the separator and bypass the main separation chamber.  Class I separators are designed to achieve a concentration of 5mg/litre of oil under standard test conditions.

Class II separators are designed to achieve a concentration of 100mg/litre of oil under standard test conditions.


    • Light and easy to install
    • Class I and Class II designs
    • Inclusive of silt storage volume
    • Fitted inlet/outlet connectors
    • Vent points within necks
    • Oil alarm system available (required by BS EN 858-1 and PPG3)
    • Extension access shafts for deep inverts
    • Maintenance from ground level
    • GRP or rotomoulded contruction (subject to model)

To specify a nominal size bypass separator, the following information is needed:-

    • The calculated flow rate for the drainage area served
    • Our designs are based on the assumption that any interconnecting pipework fitted elsewhere on site does not impede flow into or out of the separator and that the flow is not pumped
    • The required discharge standard. This will decide whether a Class I or Class II unit is required
    • The drain invert inlet depth
    • Pipework type, size and orientation

contact_us  to find out more information


Sizes and specifications for the Bypass Separators

Contact Us


03 544 4365
16 Gladstone Road
Richmond, Nelson 7020

P.O.Box 3581,
Richmond, Nelson. 7050