Water Separation - Large, heavy amounts of liquid droplets or particles from a compressed gas flow are separated by means of gravitational forces, centrifugal forces, inertial effects, etc. The differential pressure is constant and a high separation efficiency is guaranteed over the whole specified flow rate range.
Dry Type Filtration - Solid contaminants are separated from the compressed gas system. The solids contact the fibres of the filter media where they remain. A coarse and a fine coarse media filter protects the fine filter media, increasing the service life. The differential pressure (dry) increases with an increasing amount of contaminant. The elements can be operated from inside to out or vice versa. The preferred direction of flow is toward the finer filter fibres, i.e. from out-to-in.
Wet Type Filtration - Liquid contaminants from the compressed gas flow are separated using a fine multi-layer filter media in combination with a drainage media (coalescing filter). The liquid contaminants contact the fibres of the fine filter media, move along the fibres due to the compressed gas flow and form larger droplets when they are merged (coalescing effect). The droplets are absorbed by the drainage media, discharged to the filter element bottom due to gravitational forces, and drop off the filter element. Theoretically, the differential pressure (wet) is constant. However, it rises as the filter element is continuously loaded with liquid and solid contaminants. The direction of flow is toward the drainage media, i.e. from in-to-out.
Oil Vapour Adsorption - Compressed gas flow is separated by means of absorption to activated carbon. The CNG becomes virtually oil-free which cannot condense into a liquid any more. There is often a filter media downstream of the activated carbon in order to eliminate activated carbon abrasion particles (abrasion-free activated carbon filter). The differential pressure (dry) is constant. The direction of flow is always toward the media, i.e. from in-to-out. Liquid oil or water would dramatically reduce the retention capacity of the activated carbon for oil vapour and should, therefore, be separated in advance using appropriate grade filters.