High quality inline filter casings and the elements they contain, are an essential part of compressed air treatment. They are the primary defence for removing condensed water, particles, oils and vapours along with other debris, before it clogs and disables your pneumatic system.
To get the best service life from your inline filtration system the following should be observed;
Install a simple centrifugal water separator prior to the first stage of filtration. This will remove condensed water and oils in liquid form. This reduces the workload on the remaining filters. It’s essential that a reliable automatic drain is used. Condensates must be removed as they accumulate. A simple water separator has no internal filter element to block up, its only operating cost is limited to auto drain maintenance.
The second and third phase of filters are normally coalescing type filters with micron ratings of one micron and one mg/m³ down to the second filter at 0.1 micron and 0.01 mg/m³ oil removal. These filters are the real workhorses of the system. Using direct impact, Brownian Motion and Interception these elements remove solids, liquids and coalesce vapours into liquids for easy removal to the base (or quiet zone) of the filter casings for removable an automatic drain.
The final phase of filtration can be oil vapour removal, this level of filtration can be optional or mandatory depending on what the c/air is being used for. By using an activated carbon filter element or canister, oil vapours can be removed from a c/air system quite easily. The elements and casing should not be exposed to liquids; the air should be as dry as practically possible to ensure reasonable element life. Activated carbon filters must be preceded by two high efficiency coalescing filters to ensure that oils and liquids are removed prior to the activated carbon elements. A/carbon elements are not designed for liquid and solids removal. They are installed to prevent the last traces of hydrocarbons from infecting the airline. The elements will have half the service life of a coalescing filter.
Filter should be sized for air flow, we normally recommend to have a 20% overdesign on max air flow to ensure good (long) service life intervals. All filters should have differential gauges indicating the change out time for the filter elements. If this D/P indicator’s gauge is followed and filters changed out when indicated, the pressure loss across the filter will be low. If the elements are left in service too long the pressure drop will increase and will lead to expensive power wastage at the compressor room. Don’t leave the elements in too long, it will cost you money in pressure losses!
To really get the best from your compressed air system compressed air filters should be operated in tandem with a properly sized refrigeration air dryer.
It must be remembered that water in your airline will eventually evaporate, oils do not evaporate, they can lay in a compressed air piping system for years creating havoc with your c/air quality plans!
In the Auto Refinishing industry you require very high air quality, consider having regular audits for dew point, particle and oil monitoring carried out at regular intervals. Or install this equipment in the system and permanently monitor your air quality for dew point (water content). This can assist in preventing a breakthrough of contaminated air into the c/air system.
In terms of local environmental legislation it is against the law to allow oils from any source to pollute ground water. Use a simple and effective condensate separation system to prevent the pollution of our precious dams and rivers.
Artic Driers International is a family operated compressed air treatment company with 25 years expertise in the compressed air treatment industry – visit our downloads page for more essential information at www.articdriers.co.za