As a seafarer on a merchant ship or as a ship manager/owner of a vessel, one of the biggest nightmares is that of any kind of oil pollution accident on a ship.

A ship produces oil and water mixture on a daily basis which needs to be separated from each other before discharging the dirty water out of the ship using equipment such as an oily water seperator.

A ship engineer may work with 5-10 different makes of marine engines, but he/she is more likely to encounter many more types and makes of OWS in his/her career span. Even for PSC inspectors and surveyors, an oil water seperator (OWS) has always been a preferred choice of machinery on the ship for inspection. Hence, it is imperative to know and understand the basics of oil and water seperator design and how an oil and water seperator works.

As the name indicates, the function of an oil-water seperator is to separate the maximum amount of oil particles from the water to be discharged overboard from the engine room or cargo hold bilges, oil tanks and oil-contaminated spaces. As per maritime regulations, the oil content in the water processed from the OWS must be less than 15 parts per million of oil.