The end cap, as an important component of the filter element, is usually made by stamping or machining processes, and the materials include stainless steel, carbon steel, aluminum and other metals. Its design features include a certain depth of glue injection groove to ensure sealing performance. In addition, the radial end cap is specially equipped with an O-ring groove to further enhance its sealing effect.

Air filters are generally classified into several grades based on their filtration efficiency, such as primary, medium, high, and ultra-high efficiency, with specific standards varying by country.

The types of filter sealing rings are mainly classified by material and structural type. The materials include multiple types of high-molecular materials such as nitrile rubber, fluorine rubber, and silicone rubber. The structural types cover O-rings, V-rings, lip seals, and others.

1. Coarse filtration: Coarse filters  have a wide range of filtration precision typically, generally between 50 μm and 500 μm. They are mainly used to filter larger particles or impurities, such as leaves, sand and gravel, etc., to protect the equipment and pipelines in the system.

Filter oil leakage may be caused by various reasons.