The following points are to be followed while operating OWS:
1) OWS overboard manual discharge valve is to be kept locked and keys are to be kept with the chief engineer. Open the lock and overboard valve. Open all the other valves of the system.
2) Open the desired bilge tank valve from which the oily water mixture is to be discharged from OWS.
3) Open-air if the control valves are air operated.
4) Switch on the power supply of the control panel and OCM unit.
5) Fill the separator and filter unit with fresh or seawater to clean up and prime the system till the water comes out from the vent of the second stage.
6) Start the OWS supply pump which is a laminar flow pump and one that will supply the oily water mixture to OWS.