6. Tilted Plate Interceptor (TPI)/ Corrugated Plate Interceptor (CPI) Corrugated Plate Separators (CPS) provides economical and effective removal of free oil and solids from wastewater by gravity, in a smooth, efficient automatic flow. Gross, free oil droplets rise, and the flow containing residual small free droplets and solids particles enters the CPI in a laminar flow condition. Series of parallel plates, arranged to allow small, free oil droplets to coalesce and separate from the carrier fluid. Separation is based on the differences in the specific gravities of the fluids and the liquid temperature Separated oil rises to the peaks of the corrugations in the parallel plates. At the top of the unit, the separated oil forms a layer and is skimmed by an adjustable trough or weir.