CPI Units

CPI (Corrugated plate interceptor) or TPI (Tilted plate interceptor) separators are predominantly used in separation of free oil from effluent water or suspended solids for oily water treatment in an OWS (oily Water System).

The basic principle of difference in gravity between the phases (liquid – liquid or solid – liquid) is employed in an OWS in separation of the two phases. This phenomenon is defined as “Gravity Separation”.

It is therefore apparent that the phase with high density will settle and with lower density float to the surface of fluid. In an OWS, the effectiveness of this technique is subjected to various factors such as difference in the density, viscosity, factors of the medium, temperature, turbulence, and also the nature of impurity etc.

In some cases chemical coagulation and flocculation is needed for removal of the impurity by making them heavier or lighter.

KASRAVAND CPI Units are designed to remove free oil and suspended solids from water as a primary stage of water treatment and utilize plate packs as the main separation device. The plate packs are designed with specific spacing and alignment to allow solids to settle and fall to the bottom while simultaneously allowing oil drops to rise and coalesce, thereby reducing the oil and solids loading from the downstream water treatment train and smoothing out flow slugging.

The Tilted plate pack (CPI) separator offered by Paramount with technology acquired from M/s. PWT, Holland provides an extensive reduction in surface area requirement of a separator by introducing multi-layer separation wherein area required is reduced considerably depending upon number of such layers. It is feasible to achieve almost complete removal of all the particles which would not have normally be achieved by a single large surface separator. This is possible because of considerable increase in the surface area of the unit, within the same depth. In most of the cases the plates are installed at an angle of 45°deg. or more and thus the separated material can be collected and removed by gravity.

The corrugated plate pack in a TPI/ CPI separator, used in Oily water treatment for removal of free oil, is the heart of our various purification systems consisting of number of parallel corrugated plates. A Plate pack is a housing of flat plastic plates (strengthened by resins) and stiffened by a frame made from plastic material (strengthened by resins) and/or stainless steel.

The number of plates in a Plate pack is determined by in-house developed calculations, based on the long experience acquired by supply of the separators to various industrial applications. The number of plates per Plate pack is also factored to a certain extent on economy of size of the separator. The number of Plate packs per TPI/ CPI separator is calculated based on the effluent flow and its characteristics to the unit.

The CPI(corrugated plate interceptor) Oil Separator is an oil-water gravity separator, developed with Shell’s technology, and is suitable for oily wastewater treatment. CPI Oil Separator enables high efficiency gravity separation with corrugated plates, providing excellent treatability with a high flow rate. The simple structure makes it possible to reduce the construction cost and facilitates maintenance.

  1. The corrugated plates are located at short intervals, providing high oil-water separation efficiency. This makes it possible to stably treat rainwater even when the amount of rainwater treated is two or even four times larger than usual.
  2. Compared to the PPI (Parallel Plate Interceptor), the CPI Oil Separator requires about 2/3 the installation area.
  3. Compared to the PPI, the CPI Oil Separator has a relatively low construction cost.
  4. The simple structure facilitates maintenance.
  5. The CPI Oil Separator uses a molded synthetic resin that is highly resistant to corrosion, acid, and alkali, such as FRP, and is suitable for water quality.
  6. The compact structure eliminates any concern about plastic deformation.


The advantages of KASRAVAND's range of CPI Units include:

  • Low operating and maintenance cost
  • Proven robust and reliable design
  • Pressurized or non-pressurized design
  • Automated controls for unmanned operation