Liquid coolant filters are used in compression - ignition big engines in trucks and heavy machines. Their appearance is similar to spin-on filters. Liquid coolant filters function in engine cooling system as by-pass filters where only part of the liquid flows through. The main function of these filters is liquid coolant filtration and efficient trapping of solid contaminants. The filter medium is made of special filtration materials, which traps Cabin, corrosion products and sludge resulting from degradation of substances protecting cooling system from scale, corrosion and premature corrosion caused by cavitation. In most cooling liquid filters there are special blocks with active substances - corrosion inhibitors, which by slow releasing into the cooling liquid, replenish the level of components being degraded during exploitation, maintaining liquid thermal conductivity on the same high level, as well as liquid anticorrosion and anticavitation properties.