The OCM continuously monitors how much oil is in the water that is pumped out the discharge line of the OWS system. The OCM will not allow the oil concentration of the exiting water to be above the
Marpol standard of 15 ppm. This standard was first adopted in 1977 with Resolution A.393(X) which was published by
IMO. These standards were updated various but the most current resolution is MEPC 108(49). The oil content meter will sound an
alarm if the liquid leaving the system has an unsatisfactory amount of oil in the mixture. If it is still above that standard, then the bilge water will be reentered into the system until it meets the required criteria. The OCM uses light beams to determine how oily the water in the system is. The system will then gauge the oil concentration based on a light intensity meter. Modern
oil content meters also have a data logging system that can store oil concentration measurements for more than 18 months. The new MEPC 107(49) regulations have set out stringent actions that require the OCM to be tamper proof and also the OCM needs to have an alarm that sounds whenever the OCM is being cleaned. Third, is a computing unit which calculates how much oil has actually been discharged along with the day and time of the discharge. If the OCM computes that the oily discharge is above the 15 ppm standard, the
oily water separator needs to be checked by the crew. There are three types of oil that the oil content meter needs to check for and they are
fuel oil,
diesel, and
emulsions. == See also ==