USCG Technical Advisory on Oil Content Monitors

22 September 2008

SHIPOWNERS and those involved with the maintenance, operation, inspection and testing of Oily Water Separators (OWS) and Oil Content Monitors (OCM) need to be on the lookout for evidence of interference with the proper functioning of the equipment. And US Attorneys Holland & Knight have highlighted a recent United States Coast Guard (USCG) Technical Advisory which seeks to raise industry awareness about the USCGs concerns about a particular OCM.

A standard set-up is that the OCM monitors samples from the discharge line of an OWS. If the OCM detects that the oil content is higher than the permissible limit then the OCM causes the overboard discharge valve to close. And many designs of OCM incorporate a separate fresh water line that is used to flush traces of oil from the monitoring equipment.

The USCG Advisory reports that they consider the pre-2005 version of one model of OCM to have a unique vulnerability to tricking. The outcome of the tricking discussed in the Advisory is that the OCM operates as if the OWS discharge sample is passing the sensor when in fact all that is flowing through the OCM is fresh water. As a result, the overboard discharge valve may not close regardless of the oil content of the OWS discharge.

Details of the model involved and the USCGs advice on how to make the tricking more difficult are contained in the Advisory, which has been posted on the Holland & Knight website. It can be accessed by clicking here.