Industrial oils are mainly used to lubricate friction joints of different industrial machines, textile units, ventilators, and pumps. In addition, industrial oils may serve as a basis for technological and plastic lubricants or as hydraulic fluids. They are divided into two groups according to their purpose: general and special. The range of these products has been extended considerably due to the development of alloyed industrial oils.
General purpose industrial oils are used to lubricate different joints and working parts of equipment in different branches of industry. Special purpose industrial oils are used in specific areas.
Generally speaking, oil products that serve as lubricating materials are resistant to external effects due to their complicated chemical structure. But, when affected by unfavorable conditions during operation, industrial oils are prone to significant chemical changes. Such oil products become unfit for use and should be disposed of according to existing rules and requirements for proper disposal. Used oil should be managed very carefully since it can do much harm to flora and fauna if it is haphazardly discharged into the environment.
During operation, industrial oils should be regularly filtered so as to prevent the lubricated surface from being damaged by mechanical impurities and in order to extend the useful service life of the oil product.
Filtration in theory and practice removes contaminants from industrial oils. The method of oil processing is determined by the nature of its use and the contamination level of the oil. As of today, there exist mechanical, gravitational, centrifugal and magnetic type filtering systems.
Mechanical filtration is the most widespread since it is simple and relatively trouble free. Paper, felt, nets, or wire can be used as a filtration material. There are both fine mesh filters and coarse mesh filters. Fine mesh filters remove impurities of a very small size while coarse mesh filters are used to remove larger sized contaminants. The fine mesh filters are mainly made of paper and felt while coarse mesh filters are usually composed of wire or net materials. Industrial equipment that requires high purity oils are usually equipped with both types of filters.
The gravitational type filters are driven by gravitational force that makes the contaminants with a higher viscosity than oil settle down away from the main body of the fluid. This method is mainly used together with fine and coarse mesh filters.
Centrifugal filtration is a kind of gravitational filtration. According to this method, all unwanted impurities are removed by strong centrifugal force that is in centrifuges.
Centrifugal purification may be used as an independent method or together with fine mesh or coarse mesh filters.
Magnetic filtration uses a non-powered magnet or an electromagnet as a filter. The main disadvantage of this method is that only ferromagnetic particles can be removed.