The MOP automatic overflow protection provides safe operation in connection with controlled ventilation for tanks carrying treated offshore contaminated bulk liquids.

The device ensures free ventilation and prevents unwanted liquids from reaching the PV valves.The MOP system is a ready to action configuration ensuring safe ventilation without the use of manual procedures. The pressure setting of the MOP is to be adjusted according to the set pressure for the pressure valve and is typically to have a higher pressure setting to avoid premature opening.

​The MOP automatic overflow protection system provides safe operation in controlled ventilation for tanks carrying treated contaminated bulk liquids​ The MOP system provides free ventilation and prevents unwanted liquids from reaching the PV valves.​ If no protection device is in place to stop the uncontrolled flow of the mentioned liquid into the PV valve, this will flood the valve with a solid substance compromising the controlled ventilation leaving the valve clogged and inoperative. With the introduction of the MOP, cargo tanks are protected with regards to excessive pressure - created by vent pipes beeing flooded by heavy density liquid