U.S. Department of Energy - Energy Efficiency and Renewable Energy

Federal Energy Management Program – Operations and Maintenance

Diagnostic Tools for Fans

Air moving systems emit very distinct sound patterns around bearings and fan blades. In most cases, these sounds are not audible to the unaided ear or are drowned out by other equipment noises. Using an ultrasonic detector, the analyst is able to isolate the frequency of sound being emitted by the bearing or blades. Changes in these ultrasonic wave emissions are indicative of changes in equipment condition—some of these changes can be a precursor to component degradation and failure.

Within air moving systems, there are many moving parts, most in rotational motion. These parts generate a distinct pattern and level of vibration. Using a vibration analyzer and signature analysis software, the analyst can discern the vibration amplitude of the point on the equipment being monitored. This amplitude is then compared with trended readings. Changes in these readings are indicative of changes in equipment condition.