Compressed Air Best Practices - March 2008 - (Page 34)

| 03/08 Compressed Air Industry FOOD PROCESSING | THE VACUUM FORMATION PROCESS IN B U I L D I N G C O M P R E S S E D A I R F I LT E R E L E M E N T S Inertial Impaction: Smaller particles in the 0.2 to 2.0 micron size range are the most challenging to capture. Particles of this size, which conform to the air stream, are collected as they travel through the torturous path of fibers inside the element. Once a particle of this size encounters a fiber approximately one half of its physical size, it is captured and adheres to the fiber. Diffusion: The diffusion process commonly referred to as Brownian Motion captures particles 0.2 micron and smaller. Particles of this micron size are small enough to deviate from the air stream, are not affected by gravity and move in a random motion through the element. The erratic movement increases the likelihood of the particle coming in contact with a fiber within the element. The Vacuum Formation Process Micro-Filtration, division of Numatics, has been producing high performance filtration media since 1986. A proprietary vacuum formation process allows the manufacturing to be controlled to a point where all stages, from the selection of the raw material to the finished product are tightly governed. 1 The vacuum formation process starts with selecting the required grade of borosilicate fiberglass micro-fiber. Filtration performance, from micron retention rate to pressure drop is dictated by media grade selection. Since the micro fibers vary in diameter and length, each will exhibit unique performance characteristics. A pre-measured quantity of fiberglass material is added to a polypropylene mixing barrel containing into a proprietary solution. The solution is commonly referred to as slurry. The slurry is mixed for a specified period of time and then added to a stainless steel formation tank. The pH level within the tank is controlled allowing the fibers to properly combine and “floc.” Flocculation is defined as a “process of contact and adhesion whereby fine particles of a dispersion form larger size clusters.” A fixture surrounded by a corrosion resistant support is immersed in the formation tank. Hole diameter spacing as well as the circumference and length of the fixture dictate the elements’ physical size, density, filtration performance and flow capacity. The inner media wrap initiates the coalescing process by acting as a disperser. Vacuum is drawn on the fixture building a random matrix of glass fibers. Submersion time and vacuum pressure are regulated dependent upon desired filtration grade. Large diameter fibers are first to collect on the fixture allowing the smaller diameter glass fibers to migrate unabated. Once the fixture has collected larger fibers, smaller fibers are collected onto what is now the interior of the element. The remaining large fibers are collected creating an element with a course to fine, back to course pore structure. A torturous path has now been created. The converging/diverging pore structure captures submicronic particles to 99.9999+% efficiency. 2 3 4 5 Vacuum Formation Tank 34 www.airbestpractices.com 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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