Compressed Air Best Practices - February 2009 - (Page 19)

Focus Industry POWER PLANTS | 02/09 | In this article I will focus on Part 1 of ISO 8573 and describe why the standard was developed, how it should be used and what the future holds for this standard in the compressed air industry. But before we look at Part 1 of ISO8573, we need to take a look at what causes compressed air to be “impure.” How successfully compressed air stream cleanliness requirements are met can have a dramatic impact on overall plant operating costs. Excessive contamination shortens the life of components and systems, adversely affects product quality, can result in excessive maintenance costs and can even create health and safety problems. Contaminants in the form of solid particulates, oil aerosols and vapor, water aerosols and vapor and even unwanted gaseous vapors can be introduced from the plant environment, ingested by the compressors or created by the air compressor and distribution system. While many compressed air applications require a high degree of purity, all compressed air applications work better if the air is clean and dry. However, when the air leaves a compressor, it is anything but clean and dry. Sources of Contamination Contaminants in compressed air systems have three possible points of origin. They can come from the air drawn into the compressor, from internal compressor mechanisms and from the compressed air distribution system. Compressors draw in virtually all particles, vapors and gases in the air within a six-foot radius of the inlet. Smaller particles, less than 10 microns in size, can be drawn in from a larger radius. The compressor inlet filter is designed to stop larger particles that could cause rapid wear of compressor parts. This design prevents excessively frequent replacements of the air intake filter element, but it does little to protect sensitive applications downstream of the compressor. Most of the airborne particles smaller than 10 microns can enter the compressor. Also, any gases and vapors around the intake will enter the compressor and become part of the compressed air supply. These include combustion by-products such as carbon dioxide, carbon monoxide, nitrous oxides or sulfur dioxides. Another factor affecting air contamination is that during compression to 100 psi, the air volume is reduced by a factor of seven, meaning seven cubic-feet of ambient air becomes one cubic-foot of compressed air. The result is an increase in the concentration of airborne particles in the compressed air stream. After compression, some of the most common airborne contaminants include dirt and pollen particles, iron oxide (rust) particles, microorganisms, unburned hydrocarbons, liquid water, water aerosols and water vapor and oil aerosols and vapor. Now that we know what the contaminants are made up of, we can take a look at how the ISO standard is used to classify the type and amount of contamination in compressed air. 19 http://www.awarenessideas.com

Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - February 2009

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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