Three Common Types of Air Filters

Air filters are a vital component in the process of compressing air. Strict purity standards in air compression require the removal of a variety of contaminants such as particulates, vapors, and oil aerosols. Contaminants can infiltrate the compressed air from a range of different sources. Corroded pipes can introduce pollen and dust particles into the compressed air, while intake air can add harmful particulates to the compressed air. Donaldson compressed air filters fall into three categories, namely the dry particulate filters, vapor removal filters, and coalescing filters.

Dry Particulate Filters

These air filters are used for removing desiccant particles from the absorption dryer. Dry particulate air dryers operate the same as coalescing filters by capturing and retaining dust and pollen within the air compressor.

Coalescing Filters

Coalescing filters are designed to remove aerosols and water from the compressed air. Coalescing filters capture small water droplets, which form large water droplets that are then taken out of the air compressor by the filters. Coalescing filters are equipped with a re-entrainment barrier that prevents small water droplets and aerosols from reentering the compressed air. Oil and water are the common liquids that coalescing filters can remove. These compressed air filters can also trap particulates within the air compressor and remove them from the compressed air.

Vapor Removal Filters

These filters are designed to remove any gaseous lubricant that might have gone past the coalescing filter. However, vapor removal filters use an absorption process, so they are not ideal for capturing lubricant aerosols. Vapor removal filters often get saturated with aerosols quickly, which can render them useless within a short period. But passing the compressed air through a coalescing filter before pumping it through the vapor removal filters can help prevent this.

Uses of a compressed air system can help determine what types of air filters are needed. Whether an air compressor is designed to remove basic contaminants or for high infiltration levels, cleaning it is an essential step in air compression. But air filters can, in short, help you achieve safe, clean compressed air.