Compressed Air Best Practices - February 2009 - (Page 20)

| 02/09 Focus Industry POWER PLANTS | AIR STANDARDS Solid Particulate Maximum Number of Particles per m3 Purity Class 0 1 2 3 4 5 6 7 8 9 100 100,000 — — — — — — — 0.1–0.5 microns 0.5–1 micron 1–5 microns Particle Size micron Concentration mg/m3 Vapor Pressure Dew Point Water Liquid g/m3 Oil Total Oil (Aerosol, Liquid and Vapor) mg/m3 As specified by the equipment user or supplier As specified by the equipment user or supplier 1 1,000 10,000 — — — — — — 0 10 500 1,000 20,000 — — — — — — — — — ≤5 ≤ 40 — — — — — — — ≤5 ≤ 10 — — As specified by the equipment user or supplier -70 °C/-94 °F -40 °C/-40 °F -20 °C/-4 °F +3 °C/37 °F +7 °C/45 °F +10 °C/50 °C — — — ≤ 0.5 ≤5 ≤ 10 ≤ 0.01 ≤ 0.1 ≤1 ≤5 — — — — — Chart taken from ISO8573.1 : 2001 The Purity Classes The current version of ISO8573 Part 1 was published in 2001 and is currently in the process of being revised. Every five years, ISO standards are reviewed to determine whether they are still timely, accurate and useful to the industries that they serve. If the Working Group, which is made up of volunteer industry experts, decides that the standard requires no revision, then nothing is done to change the standard, and it retains its current publication date. If the standard is revised, then a new publication date is assigned to it once the revision has completed the required balloting procedure. When referring to an ISO standard, it is common practice to include the publication date, so you may see Part 1 of this standard referred to as ISO8573.1 : 2001. There are three categories of contaminants that have been assigned classes in ISO8573.1 : 2001. The first category is solid particulates. The second category is made up of a combination of liquid water and water vapor. The third category is called oil, and it consists of the sum of the liquid oil (in aerosol or liquid droplet form) and oil vapor. The chart above summarizes the three categories of contaminants and shows the limits of contamination that are required to differentiate one purity class from another. The purity classes range from the cleanest, Class 0, to the most impure, Class 9. Note that not all of the categories have the full range of classes, only the water category does. Also, notice that Class 0 does not have any numbers associated with it in any of the categories. In the text of ISO8573.1 : 2001, Class 0 is defined by stating, “As specified by the 20 www.airbestpractices.com equipment user or supplier and more stringent than Class 1.” It is very important to understand that Class 0 does not imply that there are no contaminants present; it simply means that there are fewer contaminants than in Class one. Solid Particulates There are eight possible classes for solid particulates, from Class 0 to Class 7. Class 0 is the most pure, but it is numerically undefined other than to say that it must be more pure (fewer particles in each size range) than Class 1. Classes 0 through 5 are defined by the number of particles in a particular size range, in one cubic-meter of compressed air. Measurement methods are described in Part 4 of ISO8573 for Classes 0 through 5. Classes 6 and 7 are used to describe compressed air that is typically too “dirty” to be measured with a particle counter. Instead, mass measurements are used to determine the amount of particulate contamination in the compressed air, according to Part 8 of ISO8573. Water There are 10 possible classes for water contamination, from Class 0 to Class 9. Class 0 is the driest, but it is numerically undefined, other than to say that it must be drier (a lower pressure dew point) than Class 1. Classes 0 through 6 are defined by the pressure dew point of the compressed air. Pressure dew point is defined as the temperature at which moisture begins to condense in the pipes and storage tanks http://www.airbestpractices.com

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Compressed Air Best Practices - February 2009 Contents From the Editor Utility-Air News Compressed Air Audit of the Month Air Standards Instrument Air in Nuclear Power Plants Seven Sustainability Projects for Industrial Energy Savings The Pneumatic Advantage Personal Productivity Resources for Energy Engineers Wall Street Watch Advertiser Index Classifieds

Compressed Air Best Practices - February 2009

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