Compressed Air Best Practices - March 2008 - (Page 33)

Compressed Air Industry FOOD PROCESSING | 03/08 | BY JOHN BALL Compressed air filtration technology has evolved from a subjective art form to a quantified, highly advanced science. Today, contaminant free compressed air is a requirement in most major industries. It is specified in critical applications including pharmaceutical and semi-conductor manufacturing as well as the food processing industry. As manufacturing processes become more sensitive, the need for high purity levels of compressed air becomes increasingly important. Untreated, compressed air systems contain contaminants in the form of solids, liquids and gases. Compressed Air System Contaminants Solid contamination, present in ambient air, may be ingested through the intake of an air compressor. Typical industrial air contains nearly 4,000,000 particles of dirt per cubic foot of air. Liquid contamination is introduced in the form of water vapor or as oil aerosols generated by the air compressor. Even a well maintained oil lubricated air compressor, with an oil carryover rate as low as 2 ppm/w, will introduce as much as 4.8 gallons of oil into a compressed air system per year. Hydrocarbon vapors are also ingested through the intake of the air compressor, up to 5 ppm/w, which produce undesirable odors and small amounts of trace oils ending at the point of use. So what are the solutions? Each aforementioned contaminant may be addressed through the proper application of compressed air filters. Coalescing filters are utilized to capture submicronic particles and oil aerosols at highly efficient rates. In general filtration terms, coalescing is defined as a process whereby small, liquid aerosol droplets traveling through a filter element run together and form larger droplets. Media constructed of fibrous material is best suited for the removal of liquid aerosols. To achieve the coalescing effect, certain industry recognized principles of filtration must be honored. The mechanisms promoting effective removal of oil aerosols are: Direct Interception: This phenomena occurs when a particle 2.0 micron and larger in size, collides directly with the filter media. Since most coalescing filters flow from inside of the element to the outside, direct interception takes place on the interior surface of the element. Once the droplet is directly intercepted, it extends over the surface of the fiber onto neighboring fibers. Coalescing Process: Converging-Diverging Pore Structure www.airbestpractices.com 33 http://www.airbestpractices.com

Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - March 2008

Compressed Air Best Practices - March 2008 Contents From the Editor Utility-Air News The Compressed Air Audit of the Month: Saving Energy with Blowers in Canada Do You Provide World-Class Service? Managing Rotary Screw Air Compressors at Midwest Bakery The Difference Between Acfm and Scfm for Proper Vacuum Sizing Best Practices — Multi-Module Process Air Dryers The Vacuum Formation Process in Building Compressed Air Filter Elements Solberg Manufacturing Real World Best Practices: Measuring Pressure Dewpoint in a Compressed Air System Resources for Energy Engineers: Training Calendar & Product Picks Wall Street Watch Advertiser Index Job Market

Compressed Air Best Practices - March 2008

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