Oil skimmers are remediation devices used to remove oil from the surface of water, solvents, cleaning solutions, and other fluids. There are two basic types of oil skimmers. One type is used to filter and remove oil, debris, and unwanted materials. The other type is used to recover or capture oil in a usable state. Typically, this second type of skimmer is used to clean up oil spills in factories, refineries, and bodies of water. Applications for oil skimmers include in-plant pumps, tanks, and coolant systems as well as outdoor cooling and settling ponds. When selecting oil skimmers, important specifications to consider include capacity, removal or recovery rate, and total flow. When capacity is measured in gallons, flow is measured in gallons per minute (gpm) and the removal or recovery rate is expressed in gallons per hour (gph).
Oil skimmer. Video Credit: Oil Skimmers
Types of Oil Skimmers
Oil skimmers use several technologies. Gravity skimmers rely upon the difference in specific gravity between the oil and the water or solution. Oil floats to the top and is then removed. Belt skimmers run through a contaminated liquid continuously, using a belt to pick up the oil. Often, a wiper is used to remove the oil from the belt. Wheel skimmers pass a coated disc or wheel through the contaminated liquid. The disc or wheel picks up the oil, which is then skimmed off outside the tank. With tube oil skimmers, a rope or string is circulated through the contaminated liquid. Tube skimmers can be side-mounted for low clearance applications. Sponge skimmers use absorptive materials that are designed to capture oil, but not water or other filtered solutions. By contrast, coalescing oil skimmers pass contaminated water through a coalescing media. Centrifuge skimmers separate media by spinning, causing the denser material (water) to migrate to the outside where it can be separated. Floating weir skimmers include floats and an adjustable-height weir that can be positioned at the oil-water interface so that contaminants flow into the weir and the water is excluded. Handheld or suction skimmers are small, portable devices used in small spaces such as sumps and manholes. A weir or plate is mounted at the bottom of a pipe and lowered by hand to the interface. The suction then draws the contaminant from the water.
Oil skimmers are used in a variety of industries. For example, pulp and paper processing facilities use oil skimmers in primary oil/water settling basins. Locomotive repair shops use oil skimmers in evaporator oil/water equalization tanks. Oil skimmers are also used by food processors, automotive parts manufacturers, machine shops, and the mining industry.