Industrial facilities use different types of oils and hydrocarbons in their daily operations. The waste oil generated during these processes is normally washed off with water. However, for environmental safety, the oil must be separated from the water before disposal.
In some cases, waste oil can contaminate your coolants or cutting fluids. This lowers the efficiency of your machines and can cause lasting damage.
Oil skimmers provide a cost-effective way of separating oils and hydrocarbons from denser fluids. In this article, we will define the principles and uses of oil skimmers in industrial settings.
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How Oil Skimmers Work
Oil skimmers are simple mechanical devices that skim the surface of fluid to remove the floating oil or grease using a skimming media. Oil skimmer designs vary according to their applications.
The skimmers also use various types of skimming media such as belts, disks and ropes. The efficiency of oil skimmers is based on two basic principles of fluids, Specific Gravity and Surface tension.
Specific Gravity and Oil Skimming
Specific gravity is the ratio between the density of one fluid and the density of a reference fluid. It is also referred to as Relative Density. The reference fluid for liquids is usually water while the reference fluid for gases is air at room temperature.
Oil and hydrocarbons typically have lower specific gravity than water. This means that when a mixture of oil and water settles, the oil usually floats on the surface of the water. This is the first stage of the separation of oil from water.
Surface tension is the second principle that makes oil skimming possible. It refers to the affinity fluid molecules have to each other and other materials. Oil and water have very different surface tension characteristics. This makes oil skimming one of the most effective ways of separating the two fluids.
Oil molecules tend to have low affinity for water molecules. This makes the molecules bond better to each other and other materials than to water. When in contact with the skimming media, the oil molecules naturally stick to it and separate themselves from the water. Water has a low affinity for oil and other materials, thus it slides off the skimmer easily.
Types of Oil Skimmers
Below are the three main types of oil skimmers in use today
1. Weir Oil Skimmers
Since the oil always floats on the surface of the water, a weir skimmer is a very effective way to remove it. A weir is a barrier near the surface of a water body or container that alters the flow characteristics of the water. This skimmer allows the oil on the surface to flow over the weir into a collection tank for disposal. Weir skimmers can have manual or automatic height adjustment mechanisms. Height adjustment helps to maintain their efficiency in varying water levels.
2. Oleophilic Oil Skimmers
Oleophilic materials have a high affinity for oils and grease. They attract and absorb oil molecules more easily than water molecules. This type of skimmer uses oleophilic skimming media to ensure that it collects the maximum amount of oil from the water. They are effective when dealing with oil spills of any thickness.
3. Non-Oleophilic Oil Skimmers
Non-oleophilic material is used when oleophilic skimmers are not appropriate. This can occur when cleaning fluids such as hot alkaline aqueous parts washers. Non-oleophilic oil skimmers use belt materials that allow the oil to stick to the belt and with a vertical climb any excess water runs off back into the tank. This type of belt oil skimmer is ideal for continuous running for intermittent oil contamination. It also removes the oil before excess oil can build up and cause other unwanted problems such as bacteria growth. Please refer to Interfil