Frequently Ask Questions: Specific Applications

Can the UL101 be used to identify underground leaks?

How can you tell when a bearing is bad?

How do you establish a baseline to determine if a bearing is good or bad?

What if the bearing does not have a housing that can be reached safely in contact mode?

How do I determine if a gas leak is large enough to contemplate spending the money to fix it?

Can the UL101 be used to identify underground leaks?
The UL101 has been successful at locating and detecting gas leaks in underground pipelines up to 4 feet below ground. However, the detection of gas leaks is dependant upon such factors as the pressure, the type of soil, temperature, etc.

The UL101 has also been successful in detecting water main breaks below concrete and within walls. In one case, a water leak was detected below 1 foot of concrete and soil. The leak was minimal, but saved the building maintenance from installing a completely water piping system for an apartment complex.

Another area in which detection can be successful is in checking for valve leaks in underground systems that have some portion (such as a fire plug) exposed. In this case the solid probes may be used to listen to ultrasound generated deep below the surface.

How can you tell when a bearing is bad?
Different bearings under different conditions sound different. A bearing under small load and rpms should make a soft whirring sound when the potentiometer is adjusted to the point where you only hear the bearing under test with the UL101. A bearing under great load and rpms will naturally sound rougher. If the bearing sounds loud or is squeaking, try lubricating a little. If there is no change in the sound, the bearing may be naturally noisy, may be close to the motor, or another problematic component could be causing the sound. Continue adjusting the UL101's potentiometer down until ambient noise fades away.

If you hear a click or scraping of the bearing, there may be a scratch on the race or flat spots on the balls. When these conditions occur, they are indicators the bearings life expectancy is diminished. While an indication of one of these defects may not be critical, if two of these defects are apparent the bearing is in critical condition. The bearing should be replaced immediately. Any indication of a defect should put a red flag on the bearing and be scheduled for replacement during the next shut down. Problems only get worse, even if they are not yet critical.

If the bearing does not create any noise, this is a sign of over-lubrication - which can be more critical than a bad bearing.

How do you establish a baseline to determine if a bearing is good or bad?
You know your equipment better than anyone else because you work around it each and every day. You know what noises it naturally makes, its quirks, and its faults. A regular inspection of your equipment with the UL101 will enable you to establish the same familiarity with your equipment in the ultrasonic level that you have in the audible level.

The advantage in listening to ultrasound is like looking into a crystal ball. Whatever occurs in the ultrasonic level is a precursor to what you will hear in the audible level. But once you hear it audibly, further damage may have already occurred, multiplying your problems exponentially.

It is also a good practice to use SoundCTRL to build and maintain a history of the signals. Frequently capturing the sounds of critical equipment will help to establish trends. SoundCTRL can be used play back old recordings as well as compare the root mean squared (rms) levels and fine/course crackle counts.

What if the bearing does not have a housing that can be reached safely in contact mode?
Listening to ultrasound emitted in air will also provide an indicator of the condition of bearings, or any other mechanical components. However, use of the Solid Probe attachments is recommended because they remove any interfering ambient ultrasound such as gas leaks or electrical arcing.

How do I determine if a gas leak is large enough to contemplate spending the money to fix it? Although it is impossible to use ultrasound to measure the amount of air escaping through a hole, you can make a rough estimate of air loss based upon the size of the hole or the size of the threads. [INSERT LINK HERE ABOUT CALCULATING COSTS] However, be aware that air leaks do not fix themselves over time. They only get worse. Make a record of the location of the leak and schedule a time in the near future when you have the man-hours available to fix the leak.