Up Time Magazine- August/September 2008

to prevent excessive gain increases during prolonged intervals of silence. Most digital recorders have a feature called Auto Gain Control and it’s wonderful if you are recording an interview or documenting the minutes of a meeting or other spoken proceeding. But for recording sounds, whether it is a concert pianist or an ultrasound detector, AGC has a detrimental affect on the output file. Considering that we are recording ultrasound files so we can analyze signal peaks in a time waveform, does it make sense during the capturing of the signal to apply an algorithm that amplifies the lows and de-amplifies the peaks? Not if we are going to use the sound file for analysis, comparison, and diagnostics. So if it is your intention to record ultrasound files for reasons above and beyond simple sharing and training, be sure that your recording device has a Manual Gain Control setting to avoid signal manipulation and clipping. sound signals for analysis. It is possible, and sometimes desirable, to circumvent the digital recorder all together and go straight to your vibration data collector. Most collectors are capable of receiving an ultrasound signal and going straight to the time or frequency domain. By taking the audio output and feeding it into a vibration data collector, the ultrasonic meter can be effectively used as an intelligent sensor. By fixing the amplitude setting of the detector, the measurement chain will provide repeatable and comparable data. There is a limitation in the size of the block of data possible, and this is proportional to the sampling resolution of your vibration data collector. There are two reasons for recording ultrasound files. The first is for sharing, library building, and training. The second is for comparison, trending, analysis, and diagnostics. For those interested only in the first, choosing a suitable recording device and method is less important. For those wanting to tap into the power of ultrasonic analysis for slow speed bearings, lubrication, reciprocating compressors, and electrical inspections, the right recording device is every- thing. This application is developing fast and there have been many changes in the way we do things. There are many changes ahead. Future presentations will be application specific as we delve deeper into the specific wins being realized by those ultrasound inspectors who’ve successfully integrated AVM Ultranalysis to their predictive maintenance best practices. Allan Rienstra is the General Manager of SDT North America providing ultrasound solutions to maintenance professionals since 1991. Allan has written countless articles on practical applications for ultrasound inspections including “Strategies for an Effective Airborne Ultrasound Program”. These published works are considered the standard by companies implementing inspections programs. As a co-author of SDT’s Level 1 Ultrasound Certification Program, Allan is recognized as a leader in his field. He is a graduate of Simon Fraser University, Vancouver, British Columbia, Canada and resides in Cobourg, Ontario with his wife and two children. He can be contacted at Allan@sdtnorthamerica.com Direct to Vibration Data Collector There is a fourth method for collecting ultra- www.uptimemagazine.com 61 http://www.alltestpro.com http://www.alltestpro.com http://www.uptimemagazine.com

Table of Contents Feed for the Digital Edition of Up Time Magazine- August/September 2008

Up Time Magazine- August/September 2008 Contents Upfront Upclose Information Technology Lubrication Infrared Maintenance Management Motor Testing Precision Maintenance Reliability Ultrasound Vibration Upgrade

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