4 Specifying air quality (purity) in accordance with ISO8573-1:2010, the international standard for compressed air quality ISO8573-1 is the primary document used from the ISO8573 series as it is this document which specifies the amount of contamination allowed in each cubic metre of compressed air. ISO8573-1 lists the main contaminants as solid particulate, water and oil. The purity levels for each contaminant are shown separately in tabular form, however for ease of use, here all three contaminants are combined into one easy to use table. Specifying air purity in accordance with ISO8573-1:2010 When specifying the purity of air required, the standard must always be referenced, followed by the purity class selected for each contaminant (a different purity class can be selected for each contaminant if required). An example of how to write an air quality specification is shown below: ISO8573-1:2010 Class 1:2:1 ISO8573-1:2010 refers to the standard document and its revision, the three digits refer to the purity classifications selected for solid particulate, water and total oil. Selecting an air purity class of 1:2:1 would specify the following air quality when operating at the standard’s reference conditions: Class 1 Particulate In each cubic metre of compressed air, the particulate count should not exceed 20,000 particles in the 0.1 - 0.5 micron size range, 400 particles in the 0.5 - 1 micron size range and 10 particles in the 1 - 5 micron size range. Class 2 Water A pressure dewpoint (PDP) of -40°C or better is required and no liquid water is allowed. Class 1 Oil In each cubic metre of compressed air, not more than 0.01mg of oil is allowed. This is a total level for liquid oil, oil aerosol and oil vapour. ISO8573-1:2010 Class 0 Class 0 does not mean zero contamination Class 0 does not mean oil-free compressed air A Class 0 compressor does not guarantee oil-free compressed air Class 0 does not solely refer to oil contamination A Class 0 specification must be ‘cleaner’ than the Class 1 specification for the contaminant chosen The contamination levels stated for a Class 0 specification must also be within the measurement capabilities of the test equipment and test methods shown in ISO8573 Pt 2 to Pt 9 The Class 0 specification must clearly state which contaminant the Class 0 claim refers to i.e. “Solid Particulate”, “Water” or “Total Oil (aerosol, liquid & vapour)” Class 0 requires the user or the equipment supplier to show a contamination level as part of a written specification Example of a correctly written Class 0 specification “When preceded by OIL-X Grade AO General Purpose & Grade AA High Efficiency Coalescing Filters, OIL-X OVR Grade Adsorption Filters provide a delivered air quality in accordance with ISO8573-1:2010 Class 0 (≤0.003 mg/m³) for total oil (oil aerosol & oil vapour)” The agreed Class 0 specification must be written on all documentation to be in accordance with the standard Stating Class 0 without an accompanying contaminant specification is meaningless and not in accordance with the standard ISO8573-1: 2010 CLASS Solid Particulate Water Oil Maximum number of particulates per m³ Mass Concentration mg/m³ Vapour Pressure Dewpoint Liquid g/m³ Total Oil (aerosol, liquid and vapour) 0.1 - 0.5 micron 0.5 - 1 micron 1 - 5 micron mg/m³ 0 As specified by the equipment user or supplier and more stringent than Class 1 1 ≤ 20,000 ≤ 400 ≤ 10 - ≤ -70°C - 0.01 2 ≤ 400,000 ≤ 6,000 ≤ 100 - ≤ -40°C - 0.1 3 - ≤ 90,000 ≤ 1,000 - ≤ -20°C - 1 4 - - ≤ 10,000 - ≤ +3°C - 5 5 - - ≤ 100,000 - ≤ +7°C - - 6 - - - ≤ 5 ≤ +10°C - - 7 - - - 5-10 - ≤ 0.5 - 8 - - - - - 0.5-5 - 9 - - - - - 5-10 - X - - - > 10 - > 10 > 10 www.parker.com/gsfe Compressed Air Filters and Dryers
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