Experts have been arguing for years on the subject of generating clean oil free compressed air. At the heart of the matter lies the question: Which compressor system provides the most cost-effective way of producing oil-free compressed air? Leaving aside the claims of individual manufacturers, there is no doubt that premium quality, oil-free compressed air can be achieved with either dry-running or fluid-cooled (oil injected) compressors. Ideally, the only factor to consider when selecting an air system should be its efficiency.
The first question we should ask is “What is oil free compressed air?”
According to ISO 8573-1, compressed air can be described as oil-free if its oil content (including oil vapour) is less than 0.01 mg/m³. That is approximately four-hundredths of that contained in normal atmospheric air. This amount is so minute as to be barely measurable. But what about the quality of the air that the compressor draws in? This of course depends on local ambient conditions. Even in normal situations the hydrocarbons in the air caused by industry and traffic emissions often lie between 4 and14 mg/ m³. In industrial areas, where oil is used as a lubricating, cooling and processing medium, the mineral oil content can be far greater than 10 mg/m³. Other impurities such as hydrocarbons, sulphur dioxide, soot, metals and dust are also present.
The second question is “Why treat Air?”
Every compressor, regardless of type, draws in contaminated air, concentrates the contamination by compression and, if no measures are taken to remove it, passes it on to the compressed air network.
Despite modern beliefs around air quality in “oil free” compressors not requiring filtration it is actually very much required as the air coming out will only be as good as the air drawn in, and as we compress the air we end up concentrating the impurities we discussed earlier that occur in the local ambient conditions.
In contrast, aggressive materials neutralised and solid particles are partly washed out of the air in oil injected compressors by the oil itself. Despite the high degree of purity of the compressed air being produced in this case, treatment via air filtration is required and in both cases, whether the air is from an “oil free” or “oil injected” compressor neither types of air compression will provide air that is classified as oil-free as set out by ISO 8573-1 without suitable filtration.
Glaston Compressor Services Ltd comprises of a team of highly qualified and experienced service engineers and in-house staff that are committed to delivering total customer satisfaction.
Phone Glaston Compressor Services on (0)1695 51010