Compressed Air Best Practices - June 2008 - (Page 19)

Focus Industry PHARMACEUTICALS | 06–07/08 | Aluminum oxide, silicon oxide and various other capacitive sensors share some common traits. In all cases, a capacitor is formed between two electrodes with a hygroscopic material serving as the dielectric of the capacitor. The hygroscopic material adsorbs or desorbs water vapor in proportion to the amount of water vapor surrounding the sensor. This changes the dielectric constant of the material and therefore the capacitance of the sensor. The choice of dielectric materials is critical to the performance of the sensor. Aluminum oxide is sensitive to very low dew points, but performs less well in atmospheric humidity levels. These sensors can be economical for low dew points when compared to chilled mirrors. Thin film polymer capacitive sensors operate on the same principle as aluminum oxide sensors but use polymers instead of metallic oxides as the dielectric material. Many polymer sensors are optimized for use in atmospheric levels of humidity and are not suitable for the measurement of gases with dew point temperatures lower than -20° C. However, some polymer sensors are designed for low dew point measurement, and they typically distinguish themselves by implementing active, automatic self-calibration schemes to monitor and adjust the performance of the sensor. These sensors are cost competitive with aluminum oxide devices and offer the benefit of enhanced long-term stability. What does Vaisala recommend for measurement and monitoring of dew point? When selecting a dew point instrument for a particular application, it’s important to consider the following about the installation: p p Should the instrument be portable or fixed mount? What type of signal output is desired — local display, analog, serial communication? What other functionality is of interest — power supply, data logging, alarm relays? p p What is the expected dew point level at the intended measurement location? What is the pressure range? What is the temperature range? Will the probe be installed directly in the line or will a sample line be used for external measurement? p p p With this information specified, the field of dew point instruments that fit these criteria will be significantly reduced. Thank you. For more information, contact Steve Jiroutek, Vaisala Inc., tel: 781-537-1065, email: steven.jiroutek@vaisala.com, www.vaisala.com Motorized Ball Valves THE CONDENSATE MANAGEMENT SPECIALISTS JORC offers a product range that covers ALL condensate requirements. We provide total quality and reliability so that you don’t have to compromise—our range of versatile and cost-effective solutions are designed to meet all of your condensate management needs. Through continued investment in research and development, we offer up-to-date solutions that you can count on. At JORC we never compromise on Quality or Reliability—why should you? Magnetic Zero Air Loss Drains Electronic Zero Air Loss Drains Contact us today: JORC Industrial LLC. 1146 River Road • New Castle, DE 19720 Phone: 302-395-0310 • Fax: 302-395-0312 E-mail: info@jorc.com See our new online catalog at www.jorc.com Timer Drains Compressed Air Leak Detector Oil Water Separators www .airbe stprac tices com ai rbestp ractic es.com 19 http://www.vaisala.com http://www.jorc.com http://www.jorc.com http://www.airbestpractices.com

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Compressed Air Best Practices - June 2008 Contents From the Editor Utility-Air News A Pharmaceutical Compressed Air System Audit Talking Dew Point Puerto Rico, Pharmaceuticals and Airequipo Inc. Oil-Free Rotary and Oil-Free Centrifugal Compressor Comparison SMC: Managing Energy and Dew Point in Pneumatic Systems Utility Grade Compressed Air Systems Training Calendar & Product Picks Wall Street Watch Advertiser Index Job Market

Compressed Air Best Practices - June 2008

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