US warns on BilgMon 488 bilge alarm deficiencies

Malcolm Latarche

Malcolm Latarche · 02 August 2019


Deficiencies found on four ships’ oily water separators (OWS) has prompted the USCG to publish a marine safety lessons learned bulletin.

Marine Safety Detachment Port Canaveral Port State Control Officers discovered that the entries in the Oil Record Book did not correspond to the bilge alarm data being displayed by the bilge alarm / oil content meter. The 15ppm bilge alarm is required by MARPOL to record date, time, alarm status and the operating status of the 15ppm bilge separator. The recording device should store this data for at least 18 months and be able to display or print a protocol for official system inspections as required by IMO Resolution MEPC.107(49), Revised Guidelines and Specifications for Pollution Prevention Equipment for Machinery Spaces of Ships.


In each of the four cases, the USCG issued a deficiency on the Port State Control Report of Inspection (Form B) requiring that each vessel needed to verify the validity of the entries in the bilge alarm data log against the entries in the Oil Record Book. The deficiencies found were required to be rectified to the satisfaction of Recognized Organization, Flag Administration, and the Coast Guard prior to the vessels’ departure from port.

The specific monitor in all these cases was the BilgMon 488 model manufactured by Brannstrom, a Swedish company. The older model BilgMon 488 has a battery inserted behind the circuit board of the bilge alarm that the crew cannot replace. The purpose of the battery is to maintain the stored data and Real Time Clock (RTC) when the unit is disconnected from a power supply. The circuit board contains two contact points that provide the ability to measure the battery voltage. In all four cases, the battery voltage was extremely low and failed to provide the required 2.5 volts necessary to maintain the stored data without error. As a result, when the data was viewed on the LCD screen it was scrambled and inaccurate.

The operator’s manual for this model clearly states that the battery should not be removed under any circumstances. Furthermore, a red warning sticker is affixed to the circuit board. Attempting to remove the battery in this circumstance may cause an unrecoverable error, failure and data loss. A manufacturer’s representative indicated that the battery was originally designed to last the lifetime of the device and that if the RTC stops due to a power supply failure, combined with a low back-up battery voltage, the unit is locked down and the display reads “RTC check: FAILED.”

The newer model BilgMon 488 is equipped with a replaceable battery, indicated below by the yellow arrow. As a result, when the battery weakens, the unit display will read “Batterylow: 0.5V Replace battery.” The battery can then be safely removed because it utilizes a capacitor that ensures enough energy to maintain the stored data for several hours. Click here for the applicable manual.

Master units on older models have serial numbers starting with “A,” “AE,” “BFA,” and “EDA.” The newer type of master unit has serial numbers starting with “4A,” “4AE,” “4BFA,” and “4EDA.”

As a result of these discoveries the USCG strongly recommends that ship owners and operators whose vessels use the BilgMon 488:

  • 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.
  • Maintain awareness that Port State Control Officers performing MARPOL examinations will verify that the BilgMon 488 is recording data properly and is aligned with the ORB entries.
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