The main function of the filter is to control the pollution level of the hydraulic system, ensure the normal working performance of the system, and extend the service life of the components. The selection of filters with low filtration accuracy or little maintenance of filters will lead to excessive pollution of the system, making the system unreliable or damaged hydraulic components. The performance of the filter mainly depends on two aspects, on the one hand, the ability to filter pollutants, that is, the filtration accuracy; On the other hand, it includes scale capacity, pressure drop and flow capacity. The correct selection of filters requires careful evaluation according to the technical requirements of the entire hydraulic system and the characteristics of the various types of filters.
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The selection of the filter includes the selection of the filter type, the selection of the specification and the determination of the installation position of the filter in the loop. Among them, when selecting the filter model, first select the appropriate filter type according to the design requirements of the hydraulic system, and then select the appropriate filter model and specification according to the filtration accuracy. In addition, the following points should be considered:
① The filter can maintain sufficient flow capacity for a long time;
② The filter element has sufficient strength and is not damaged by the effect of oil pressure;
③ Good corrosion resistance of filter element;
④ the filter element can work continuously at the specified temperature;
⑤ The filter element is easy to clean and replace.
In addition to the selection of filtration accuracy, it is also necessary to determine the location of the filter installation according to the pollution sensitivity of the hydraulic system and components and the type of filter selected, so that the degree of oil contamination is as low as possible. The filter can be installed in various positions in the hydraulic system, such as the oil suction and discharge ports of the hydraulic pump, the oil inlet and outlet ports of the actuator, and the oil inlet of the sensitive element, as shown in Figure 36.
The high-pressure filter should be used at the oil inlet of the hydraulic pump, the actuator and the sensitive element, and the low-pressure filter can be used at the system oil return port and the oil suction port of the hydraulic pump. The pressure drop of the filter at the suction port of the hydraulic pump should be as low as possible to avoid affecting the self-priming capacity of the hydraulic pump.
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1- Oil Suction Filter; 2- Oil injection port/Air Filter; 3- Oil suction filter with bypass valve; 4- High pressure filter with bypass valve; 5, 6-high pressure filter; 7- Low pressure Oil Return Filter with bypass valve; 8- Low pressure filter with bypass valve independent of main hydraulic system
