BCAS 2018

www.bcas.org.uk 27 Technology Guide Class 0 compressed air When selecting new air compressors for their installations, many users (especially in the food, beverage and pharmaceutical industries) are now requesting oil free air compressors with “ISO8573-1 Class 0” certification. W hen using ISO8573-1, the international standard for compressed air purity, Class 0 is the highest purity classification available. Class 0 allows a user or manufacturer to specify an air purity which is cleaner than Classification 1 and which is still measurable using the methods and equipment of ISO8573 Parts 2 to 9. Many compressor manufacturers have taken to specifying their oil free air compressor models to Class 0, however this often leads to misunderstandings regarding the actual purity of compressed air at the point of use. Some myths ● MYTH: A lubricated air compressor is the only source of contamination in a compressed air system. ● MYTH: An air compressor can clean the air it compresses, or provide oil free compressed air. ● MYTH: An oil free compressor removes the need for some, most or all of the air treatment technologies associated with a lubricated compressor. ● MYTH: Class 0 covers all contaminants found in a compressed air system or means 0 contamination. ● MYTH: Air that is Class 0 at the outlet of the compressor will still be Class 0 when it gets to the point of use / application. Some facts ● FACT: In a typical compressed air ring main, there are 10 different contaminants present requiring treatment (regardless of whether an oil free or oil lubricated compressor is installed). ● FACT: These contaminants come from 4 different sources. ● FACT: The purification technologies required to clean compressed air from an oil free compressor is identical to that required for an oil lubricated compressor. ● FACT: Many oil free compressor designs are not totally oil-less. ● FACT: Oil vapour in the ring main cools & condenses to form liquid oil and oil aerosols. ● FACT: Old contaminated piping in a ring main contains many contaminants (including oil). ● FACT: Compressed air must be treated both in the compressor room and at the point of use. Oil free air Most users request Class 0 as they have critical applications where the presence of oil is unacceptable and by requesting Class 0, users are actually specifying the need for oil free air (not oil free equipment). There are filtration products on the market to provide the removal of all forms of oil from compressed air (liquid oil, oil aerosols & oil vapour). Some levels of filtration provide the final oil removal stage, which allows the air to be designated as “Technically Oil Free” and with an air purity (quality) classification of ISO8573-1 Class 0. Air can now be available no matter what type of air compressor is installed (even oil lubricated). Installation flexibility can mean oil free air is available just where it’s needed, at the critical points of use. Oil free filtration