Mattei is concerned there is a lack of understanding around oil-free and class 0 air
19/06/2013 Mattei Compressors Ltd
When purchasing new compressed air equipment, an increasing number of companies are including the terms 'oil-free' and 'class 0 (zero)' on their tender documents. However, rotary vane compressor manufacturer Mattei is concerned that these phrases are being used without clear understanding about what they actually mean, or what benefits they deliver.ISO8573-1:2010 is the international standard for specifying compressed air quality, and details the amount of contamination allowed in each cubic metre of compressed air. Contaminants are separated into three areas - solid particulate, water and oil - each having its own range of classes.
The class 1 standard for oil, which states that in each cubic metre of compressed air there should be no more than 0.01mg of oil, is suitable for critical applications such as breathing, medical and food. However, there is also a more stringent class 0.
Despite its name, class 0 does not equal zero contamination. In reality it needs to have less contamination in a cubic metre of air than class 1 does. The end user and the equipment supplier agree the levels as part of a written specification - so when used in isolation the term class 0 is meaningless. Meanwhile, the phrase 'oil-free' relates to a type of compressor, rather than a specific class of air.
Historically only very sensitive environments - such as pharmaceutical and food and drink manufacturing - have required compressed air with a high standard of purity. In recent years however there has been a definite shift towards compressed air users requesting 'oil-free' and 'class 0' air for more standard applications - which Mattei is raising concerns about.
Andy Jones, general manager at Mattei, says: "Our concern is that these terms are being included on tender documents without real understanding about what they actually mean or what benefits they deliver; for example it might be misconceived that class 0 air will be totally oil-free, or will improve a company's environmental credentials.
"And it's vital for specifiers to consider whether class 1 or class 0 air is truly required - and whether it is needed for the entire system or just part of it - because the more stringent the purity, the more costly it is to achieve it, especially if the oil-free compressor route is taken.
"Oil-free compressors are more expensive than oil-lubricated equivalents, in terms of the capital outlay and maintenance, as well as the amount of energy they use. In fact we'd suggest oil-lubricated compressors are 10-15 per cent more energy efficient than oil-free machines. As typically around 75 per cent of the cost of purchasing and running an air compressor over a five-year period comes down to its electrical consumption, choosing an oil-lubricated compressor can offer significant savings in energy costs.
"Since oil-free compressors don't use any lubricating oil in the compression chamber, many end users assume they will provide oil-free, class 0 air. However, this is not the case. For an oil-free compressor to ensure class 1 or class 0 purity, downstream filtration will nonetheless still be required - because outside of laboratory conditions the air being drawn into a compressor can never be entirely clean and free of hydrocarbons or other contaminants.
"It's important for end users to understand that, providing there is an adequate level of filtration, an oil-lubricated compressor can deliver high standards of air purity. Modern oil removing devices can reach exceptional levels of performance; in fact they are capable of making compressed air 400 times cleaner than the air we breathe."
There can often be legitimate reasons for end users requesting class 1 and class 0 air. However, before investing in costly equipment, Mattei is urging plant and factory managers to thoroughly assess why such high standards of purity are needed, and whether they are required for the whole plant or just isolated areas. It is also worth investigating whether it would more appropriate, cost-effective and efficient to achieve class 1 or class 0 with an oil-lubricated compressor and filtration rather than with an oil-free compressor, which will still require filtration.
For further information visit www.mattei.co.uk or call 01789 450577.
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