A strainer is a type of filter that is used to remove large contamination particles from the system. These two products do have quite a bit in common. They are both used to remove unwanted or contaminated particles from liquids or gasses.

A filter is a fine mesh screen that is used to remove impurities from oil, air, and water onboard the ship. A strainer is a type of filter that is used to remove large contamination particles from the system.

An Oily Water Separator (OWS) is a piece of equipment used on board almost all marine vessels. It is used to separate oil and water mixtures into their separate components. They are found on board ships where they are used to separate oil from oily waste water, such as bilge water before the waste is discharged into the environment. These discharges of waste water must comply with the requirements laid out in MARPOL 73/78.