Technical Circular No: 029/2019

Subject: USCG lessons learned on BilgMon 488 Bilge Alarm/ Oil content Meter.

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  • In recent inspections, Port State Control (PSC) Officers in the United States have found that the entries made in the Oil Record Book did not correspond to the bilge alarm data displayed by the bilge alarm/oil content meter.
  • On investigation the route cause was found that the 15 ppm bilge alarm systems of Oily Water Separators failed to maintain the required stored data due to low battery voltage. The purpose of battery is to maintain stored data and Real Time Clock (RTC). In these instances, due to low battery voltage, the data shown on the display was scrambled and inaccurate.
  • This issue was found in a older model of BilgMon 488 having a non-removable battery. Newer model is equipped with replaceable battery which shows the indication on display unit for replacement of battery when it weakens.
  • The models can be identified by serial number as older model starts with “A”, “AE”, “BFA” & “EDA” while newer model starts with “4A”, “4AE”, “4BFA”, “4EDA”.
  • Based on results, United States Coast Guard (USCG) has issued a Marine Safety Lessons Learned 01-19 (copy attached) recommending that shipowners should check their vessels’ bilge alarm / oil content meters to ensure they are working properly.
  • USCG has recommended as follows to shipowners and operators whose vessel use the BilgMon 488:
  1. Remind vessel engineers to routinely review the stored data available through the LCD display ensuring that the data matches the information recorded in the ORB and actual OWS operations.
  1. Maintain awareness that PSC Officers performing MARPOL examinations will verify that the BilgMon 488 is recording data properly and is aligned with the ORB entries.
  • Owners/operators and masters are requested to be guided by above and ensure adherence to these recommendations in order to avoid potential departure delays that could arise from PSC.


  1. USCG Lessons Learned 01-19


This Technical Circular and the material contained in it is provided only for the purpose of supplying current information to the reader and not as an advice to be relied upon by any person. While we have taken utmost care to be as factual as possible, readers/ users are advised to verify the exact text and content of the Regulation from the original source/ issuing Authority.

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