CREW’S VIEWS
Oil Discharge Monitoring System
Could the “white-box” be the answer to help ships stay clean and out of trouble?
captains would wish for just that. With numerous examples of magic pipes, bypass valves and the resultant fines for accidentally or purposely pumping bilge water exceeding 15ppm (parts per million) into the sea, vessel masters are ever fearful of having little control over pollution violations but all the responsibility. Even the new amendments to the Oil Record Book which entered into force on 1 January 2011 to better clarify the movements of oil residues, still requires the master’s signature at the bottom of each page not the chief engineer’s. With lesser
T accountability, rogue
engineers still persist in the illegal dumping of oily water with in excess of 15ppm despite MARPOL Annex 1. In the past, these pollution violations only ever came to light during flag/state inspections. Now, with the increased numbers of spotter planes utilised by countries such as France and the USA, as well as the large payouts given as incentives to whistle blowers
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the WikiLeaks of the ships engine-room world, masters are finding themselves being held personally accountable and on the receiving end of lengthy jail sentences. Enter Marinfloc’s White-Box System.
Like all oil discharge monitoring systems, it essentially consists of four elements, An oil content meter, A flow meter, a computing unit and an overboard valve control system, thus ticking all the boxes of Resolution MEPC.107 (49), which requires vessels to
The Naval Architect April 2011
he “White-Box” might sound like a knight in shining armour charging in to the rescue, and I know most
provide, “fail-safe arrangements to avoid any discharge in case of malfunction.” Te system is designed to only allow, the
discharge of bilge water with an oil content of less than 15ppm. Te oily water separator pump feeds the bilge water through the White-Box system. An adequate flow of this sample water is continuously fed by the flow control device to the oil content meter. An optical sensor within this unit measures light scattered and absorbed by oil droplets in the sample water. Te sensor signals are then processed by
a microprocessor, if the oil in the bilge water is less than 15ppm, a signal is sent to a 3-way valve and this valve will allow the discharge overboard only if other criteria are met. Namely, there is sufficient flow through the flow-switch, the solenoid rinse water valve to flush the meter with fresh water for cleaning purposes is not activated by the push button, and the recorder is on. Conversely, if the content of the oil is greater than 15ppm or any of the above conditions are not met, the 3-way valve switches to the ‘return’ position, returning the water to the bilge water tank. The components of the White-box are
housed in a steel cage with physical padlocks, as an added deterrent visible tamper-proof tape seals critical accesses. The system is calibrated according to the International Maritime Organization regulations by the manufacturer, and its operation is digitally recorded to a PCMCIA memory card. Tis information includes, if there is a flow through the oil content meter, the oil content itself, the position of the 3-way valve and the volume pumped overboard in litres. Te ability to
record the GPS position is also available. A screen display that can be remotely mounted in the engine control room gives a graphic indication to the engineer on watch the same information. Like the mythical unbreakable safe
however, no equipment can truly be 100% tamper proof or infallible. Tree-way valves by the nature of their construction can malfunction. OCM’s especially the older models that require daily cleaning can give erroneous readings and finally the flow switch that utilises a sight glass has an adjustment screw that can be tampered with. The latest White-box systems have
rectified some of these potential hotspots. Te flow switch which monitors the processed bilge water samples is now digital, with no moving components or sight glass making it essentially maintenance free and tamper resistant. The oil content meter requires weekly intervals for cleaning and a memory card within the unit stores information up to 18 months. Cruise lines that in the past were on
probation by the US Department of Justice use the White-Box as an addition - a security blanket if you like. Te system acts as an added barrier for anyone thinking of committing pollution violations, and as a redundancy in case of a malfunction with the bilge alarm system. Restricting access to the White-Box by the use of padlocks and keys to senior engineers further narrows the loop. Unless there is a determined collaboration between the ships engineers and electricians, the White-box in my opinion is a worthy champion for captains. NA
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