An oily water separator is a machine fitted in all ships (not just tankers) for reducing the oil content of engine room oily bilge water before it is discharged overboard.
It is usually fitted in the engine room and basically comprises one or more vertical cylinders, an inlet pipe from the bilge and outlet pipe to the overboard discharge. An oil discharge monitoring and control system (ODMCS) is a system only fitted in tankers comprising piping between the slop tank and computerised sampling and monitoring equipment (ODME) usually fitted in the cargo control room, and piping to the overboard discharge A tanker fitted with an ODMCS will also have an oily water separator in its engine room.
