Find out which type of oil water separator is best for your business.

Cleanawater on 14 July 2017

  • Coalescing plate oil water separators treat water to ~10 ppm oil content
  • Hydrocyclone oil water separators treat water to ~5 ppm oil content
  • Vertical gravity oil water separators water to ~50 ppm oil content

What is an oil water separator?

An oil water separator is a piece of equipment designed to free oil, grease, and hydrocarbons from water. It can be used in industrial settings, commercial settings where waste oil is generated or in any location where a release of oil could cause environmental contamination.

The question many people ask is: What are the different types of oil separator and which is the best one for my application? There are three different types you can choose from.

Key differences between oil separators and where they are used

 Coalescing PlateHydrocycloneVertical Gravity

Flow rate

1,000 to 50,000 l/h

> 3,000 to 500,000 l/h

720 t 3,000 l/h


Not compact

Very compact


Outlet water spec

10 ppm

5 ppm

50 ppm

In detail: oil water separator types

Coalescing Plate Separators

slack imgs

The heart of a coalescing plate separator consists of corrugated plates made from an oleophilic material. The plates are laid one on top of the other with a separation of between six and twelve millimetres between them. As the water and oil stream enters the separator and flows between the plates, oil droplets begin to attach themselves to the coalescing material. As more droplets form and attach to each other on the surface of the plate, they flow into corrugated shapes getting trapped in these plates while the water continues to flow. The angle of plate arrangement ensures water continues to flow at desired flow rates whilst oil droplets are forced to impinge on the corrugated plates. The process continues until the oil has migrated through each plate to the surface of the separator, while the water continues to flow through the plates and out through the outlet.

Separation of oil from the water is accomplished through the forces of gravity (oil being lighter than water, and the oleophilic nature of the coalescing plates. This type of separator is ideally suited as a permanent installation to treat a waste water stream before it is released to the environment or to trade waste (e.g. wash down facilities, bunds, industrial effluent).

Hydrocyclone Oil Water Separators

hydrocyclone oil water separator mining wash bayA hydrocyclone oil water separator works with the power of centrifugal force to separate oil from water. The inlet stream enters the separator at an angle into a cyclone which accelerates the flow into a spiral shape. The heavier water particles are pushed to the outer edges and fall down towards the outlet by gravity, while the light oil particles are drawn to the inner core of the cyclone and migrate upwards because of their lower density. The oil stream effluent leaves from the top of the separator.

Separation is accomplished by centrifugal forces which can reach up to 1,000 times the force of gravity. Hydrocyclone oil water separators are suited to applications with a low maintenance requirement and for applications that require a high and efficient removal of oil from water. Their high efficiency makes them an ideal solution for factory settings on process and effluent water streams.

Vertical Gravity Separators

vertical gravity separatorsVertical gravity oil separators are designed to accelerate the natural process whereby oil floats to the surface of water. The separator tank is filled with cone shaped layers of oleophilic materials. Oil particles stick to the cones and then enlarge as particles stick together until the large oil droplets float to the surface of the separator. The larger the oil droplets that are formed, the faster the separation process. The inlet stream enters near the bottom of the tank and is directed upward into the first cone. Sludge settles at the bottom, oil floats to the top and water is drawn from an outlet on the side of the tank in the bottom section.

The water and oil inlet stream is pumped into the separator with an appropriate pump to make sure no unnecessary mixing of the particles, which would hamper separation. Vertical gravity oil separators can handle a low or intermittent flow rate of hot or cold inlet streams. They are well suited to commercial or restaurant applications as well as washdown and refuelling entities. The water recovered from the vertical gravity oil separator can be recycled to be used again in a washdown operation.

Where have oil water separators been used?

Veolia Water Ballarat needed a high tech solution to deal with oil spills in a transformer bund without any interruption to operational activity. Cleanawater provided a hydrocyclone solution that seamlessly integrated with the existing infrastructure.

A coalescing plate separator was the ideal solution for New Age Caravans when they moved into new facilities with specially designed washdown and rainfall simulation bays. Cleanawater designed and installed the system with effluent meeting the local trade waste water requirements.

Contact Cleanawater for more information about oil separators

We offer highly technical expertise, excellent quality equipment and a personalised approach to your business’ needs. We can easily combine our solutions to suit your specific business, compliance and investment requirements.

Call our expert team on 1800 353 788 to discuss efficient solutions for oil separators.