Oil separator (tank) is a kind of equipment (facility) for separating oil from oil-water mixture. Its basic principle is to separate oil from water by using the immiscible nature and different densities of oil and water, and trap oil in it. Commonly used in oily sewage treatment. As shown in the above figure, oily sewage enters a large space, and its flow rate decreases, and the oil in it gradually floats up, while the water flows out from below the space. So as to realize oil-water separation. The specific structure of oil separator (tank) with different purposes will be very different for different objects, but the basic principle is the same.

The grease trap used in catering industry will be specially designed for solid sundries, box insulation (anti-freezing, anti-oil solidification) and waste oil recovery methods.