What are the main aspects of the filter's bypass phenomenon?
(1) Defects of filter media
Damage to the filter media is often caused by the incompatibility of some of the materials with the oil; it may also be caused by material fatigue due to periodic flow and frequent changes in pressure. After the fatigue formed a loophole, can not play a role in filtering. ISO2941 is a method standard for detecting incompleteness.
(2) The filter structure is incomplete
Metal filter elements are often composed of argon arc welding or brazing; most modern filter elements are rarely metallic materials, they are non-metallic fibers and are bonded with resin glue. If the welding or bonding process is not good, the filter element will be damaged after a period of use, causing leakage. Leakage at least allows some large particles to escape and return to the system. Incompleteness includes defects in the filter material, as well as the lack of sealing of the assembled assembly.
(3) The filter element and the housing part are not sealed
The seal of the filter element and the housing part is usually made of an O-ring. If the seal is damaged or destroyed during use, it will cause leakage of the filter. The O-ring can be mounted in the cartridge mount or on the filter. Usually when replacing the filter element, replace the seal at the same time to ensure a reliable seal here. This is a hidden defect and is often found in the analysis of the test results of ISO 16889.
(4) Bypass valve spool does not respond
The bypass valve at the head of the filter housing opens when the filter element is severely blocked to ensure oil in the working system. If this valve design parameter is improperly selected or manufactured, improper installation will result in oil leakage or incorrect opening and closing of the valve, resulting in filter performance degradation or failure. This problem was found in the tests of ISO 16889 and ISO 3968 as follows: the pressure difference is not established or the filtration ratio is abnormal.
