oily water separator, pollution, bilge, valve, packing gland, density, separation, reciprocating, screw pump, marpol, regulations

Oily Water Separator Oily water separators are used to separate oil from bilge water before the latter is pumped overboard. On the tank top of the engine room, we can very often find water. The water usually comes from the pump and valve packing glands, leaks, spills, washing water, air reservoir drains, and many other sources. Over a period of time, water accumulates as bilge water. The oily water separator works on the principle of coalescing small oil droplets in the water to form larger oil drops. When the oil drops become large enough, the lower density oil drops floats up and collects at the top of the vessel The water remains at the lower portion and is pumped overboard. The oil layer is pumped into an oily bilge tank which can be pumped out at an oil collecting facility when the ship arrives at a port. The small oil droplets are enabled to form larger drops with the help of gradually sloping plates installed in the oily water separator. Heaters are also employed to warm up the water and oil mixture to increase the density difference between water and oil and thus hastening the separation process. The pump used to send the bilge water into the oily water separator should not agitate the mixture because this might create finer oil particles. The pump is usually a slow action reciprocating pump or a mono screw pump