TM 55-1925-285-13&P
OPERATOR, UNIT, AND DIRECT SUPPORT MAINTENANCE
OIL WATER SEPARATOR FOR
INLAND AND COASTAL LARGE TUG (LT)
EQUIPMENT DESCRIPTION AND DATA
EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES
OIL WATER SEPARATOR (OWS)
The OWS uses the principles of gravity separation and coalescence to remove oil from water. Storage of oily
wastes in the Oily Waste Tank (OWT) prior to treatment enhances this process by allowing some of the oil to
separate in the tank, thus reducing the loading on the OWS. The OWS can process from 10 to 15 gal/min (38 to
57 L/min) of bilge water.
OIL CONTENT MONITOR (OCM)
The Model ET-35N oil content monitor system described in this technical manual is designed to monitor and
measure the amount of oil that is present in water discharged from the OWS. It is primarily intended to be
incorporated into onboard OWS installations on U.S. Military vessels. The OCM system provides control signals
to the diverter solenoid valve of the OWS to prevent the overboard discharge of effluent with an oil content
greater than 70 parts per million (ppm) while at sea, or greater than 15 ppm while in port, within 12 nautical miles
(nmi) of land, or other designated special areas of environmental concern. The ET-35N OCM utilizes the prin-
ciple of ultrasonic emulsification to affect the turbidity of oil/water mixtures, which can be accurately measured to
determine the small traces of oil in the effluent from the OWS. This system can sample effluent streams of at
least 2 gal/min (7.6 L/min) (no maximum flow rate) through a nozzle sampler, and is rated for continuous duty.
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