Cleaning the fuel carried on board by cleaning the fuel separator, filtration and sedimentation. Advocated in the slop oil tanks. The process of sedimentation is deposited on the bottom of the vessel under the influence gravitational forces of mechanical impurities and water. At the same time, from dirt to mud and fall partly Asphaltic-resinous compounds. The speed of deposition of various impurities depends on their weight, size and shape, as well as the viscosity of the fuel. The greater the difference in specific weights and fuel impurities and less fuel viscosity, the higher deposition rate.

Therefore the process of settling of diesel fuel, which has in comparison with Heavy fuel less dense proceeds more rapidly. To reduce the viscosity of heavy fuel oil (heavy oil) in the slop tanks are usually heated to 60-70 C by steam heating elements with thermostats, automatically maintaining the correct temperature. Marine fuel is filtered based on the separation of impurities contaminating its size due to the difference-through cells or slits filter and filter out particles. Fuel is filtered out in stages en route from the stock tank to fuel pump motors. In toplivoperekachivayuschih and receiving marine pump separators are placed coarse filters.

Ship separator cleans the fuel from water and small particles. After the fuel separator, it enters the supply tanks. From there goes to the engines. Before the fuel pump filters are usually applied with a finer mesh or slotted. Before engine installed fine filters. Coarse filters, the main purpose of which is the detention of large mechanical parts, are meshed with the filter elements from metal grids and slotted with filter elements drawn from separate plates (disks). In one case equipped with two filter elements, one of which can be cleaned while the other will work. Pressure drop before and after the filter typically amounts to 0.2 kgf/cm2, increasing the pressure drop over 0.4 kgf/cm2 indicates contamination, and the lack of difference – the fault filter (break the grid). Filtering materials of fine filters are special paper, felt, felt, porous bronze, ceramics, etc. In contrast to the pre-filter wash their filtering ability is not fully recovered, so these elements are periodically replaced. In recent time the work is automated pre-filter, cleaning is carried out by washing the reverse flow of fuel, which then together with the dirt down into the mud tank. For smooth, reliable operation of the fuel system sizes remaining in the fuel filter after the mechanical parts must be smaller than the gap in high-precision pairs of pumps and nozzles, and therefore should not exceed 3-5 nm.