Acoustic and Structure Borne Ultrasound

Discovering Modes of Failure that are Beyond Human Hearing

We know the storey about the seasoned technician who carried a screwdriver and would listen to the rotating bearings to determine the condition and state of failure. The issue of course is those sounds the technician heard were within the frequency of human hearing AND those sounds indicated the rotating bearings had already begun to fail. Ultrasound Testing is a sophisticated technique that captures a high-frequency sound and converts that sound to a frequency below 20kHz that is detectable by human hearing using an ultrasound detector. Sounds above 20kHz are inaudible to human hearing. Acoustic and Structure Borne ultrasound is able to identify the high-frequency and heterodyne the frequency so it can be heard. Noises produced by air movement from a fan or blower, compressed air, bearings that are short of grease, gear mesh in a gear reducer, water travelling in a pipe, gate valves that are only partially closed all produce high-frequency acoustic and structure borne ultrasound.

Mechanical

· Bearings requiring grease – Dry bearings emit a high-frequency noise that can be used to signal how much grease a bearing needs.
· Bearing Failure – Ultrasound is effective in identifying bearings that are in the earliest state of pre-failure. New bearings that have false brinelling, bearings that are loose in the bearing pocket or loose on the journal can be identified before functional failure occurs.
· Rotating Machinery Looseness – Both acoustic ultrasound and structure borne ultrasound is effective in identifying rotating equipment that either too tight or too loose. Conveyor belt rollers, out of sight scuffing and rubbing each produce a specific high-frequency signature that when captured by an Ultrasound detector can direct you to the source.

· Compressed Air - Compressed air production is not a cheap product to manufacture. Today, we see compressed air as serving many manufacturing processes, so it is very important when producing a product. However, compressed air leaks waste energy. Acoustic Ultrasound is a perfect solution to targeting system wide compressed air leaks that put the cost savings directly back into company profits. [Check out SAVE ON ENERGY for additional government savings incentives.]

· Pumps – Cavitation in pumps is very damaging to pump impellers. Severe destructive cavitation forces decimate impellers leading to poor flow, loss of head pressure, and premature and costly repair requirements. Acoustic Ultrasound is highly effective in determining pumps that have cavitation and can be used to correct leading causes of pump cavitation.

· Water and fluids Piping – Gate value in water distribution system require regular exercise to stay functional, yet it is sometime impossible to know when gate values malfunction and refuse to close. This can be a serious safety concern. Structure borne ultrasound is effective in hearing the turbulent flow as fluids pass a partially closed valve allowing identification of malfunction.

· Underground leak detection – Ultrasound when used in concert with thermal imaging is a perfect partner for detection of underground water and gas leaks. Electrical

· Partial Discharge – Traditional annual electrical testing was when technicians would discover evidence of Arcing, Tracking and Corona. New electrical inspection standards promote the use of acoustic ultrasound to detect partial discharge activity. Any electrician who opens an active electrical cabinet that has Arcing, Tracking or Corona activity is placing himself, his coworkers and the company at severe RISK of ARC FLASH. Acoustic ultrasound is used to detect such partial discharge activity BEFORE opening the cabinet.

· Electric Motor Winding Looseness – Acoustic Ultrasound is VERY EFFECTIVE in detecting loose laminations, or other electrical anomalies.