Ultrasound seems like some type of a superpower a comic book hero might have, but you might be surprised to find out that you can put ultrasound to work for you in troubleshooting, monitoring, and evaluating the equipment in your facility. From steam traps to electric motors, ultrasound data can be a powerful tool for your predictive maintenance program.
Ultrasound refers to sound waves that are at such an ultra-high frequency that they are beyond the normal range of human hearing. Many different phenomena in electrical and mechanical systems emit ultrasounds that can aid a trained technician in detecting and diagnosing problems such as vacuum leaks or under lubricated bearings.
Ultrasound equipment detects sounds within ultra-high frequency ranges and transforms those sounds to a form that can be interpreted by a technician. Many times ultrasound is plotted to show how intensity measured in dB varies across frequencies, allowing a particular frequency to become the focus of ultrasound investigation.
Filters that are part of the ultrasound equipment allow a technician to tune out other sounds that are not related to the investigation or troubleshooting process. And because sound is directional it is possible to pinpoint the exact location of a particular ultrasound source.
In addition to visual plots of intensity versus frequency, some types of ultrasound equipment can transform ultrasounds into a range that can be detected by human hearing. In such situations, a technician can wear a set of headphones to essentially “hear” the sounds and learn to recognize sounds for different electromechanical conditions.
So here is where things get interesting: when most industrial machines begin to approach a failure mode, the onset of the defect behind that failure mode results in high-frequency sounds being emitted. These sounds are usually the result of one of three things:
Each of these phenomena (friction, impact, turbulence) has its own ultrasound signature that is detectable with the right equipment in the hands of a trained technician.
Here is a list with some of the more common applications for ultrasound in an industrial setting:
Let’s take a look at some of these in more detail, beginning with ultrasound for bearing inspection and lubrication.
Identifiable ultrasound profiles are generated by friction from bearings that are either about to fail or suffering from lubrication issues (and that can be over or under lubricated). The ultrasound profile is directly related to the amount of friction involved. Bearings that are functioning correctly have a very different sound profile from those that are experiencing problems --- and this is something that a trained ultrasound technician will recognize. Not only does ultrasound detect problems, it can also be used as a tool to optimize the amount of lubricant used on a bearing.
When gases leak under pressure (either out of a system, in the case of a pressurized system, or into a system, in the case of a vacuum) they are going to create a turbulent flow. Ultrasound not only picks up on the presence of that turbulent flow, but allows the technicians to use its intensity and directionality to locate the source of the leak even in noisy environments. Ultrasound can also be used as part of a compressed air leak survey to locate leaks, aid in developing a cost estimation for the leaks, and provide key information about your facility’s carbon footprint.
Ultrasound can also be used to inspect stream traps and valves. Both steam trap and valve operation can be investigated in just about any environment. For a valve, it is as simple as determining whether you are picking up the sound of turbulent flow. When you consider how many stream traps and individual valves there are in your plant floor, it makes sense that a quick, efficient means of inspection is important.
Mechanical issues are not the only type of phenomena that can generate identifiable ultrasound profiles: certain electrical issues have high-frequency sounds associated with them, also. These include ...
In all of these phenomena, high-frequency sounds are generated because the electrical ionization involved disturbs nearby air molecules. While some electrical equipment produces a steady hum, that is far different from the types of ultrasound generated by factors such as arcing or corona.
Ultrasound is a powerful tool for PdM (Predictive Maintenance). Here are a few examples of the benefits your facility will reap if you make ultrasound a part of your PdM program:
And when used as part of PdM and Asset Condition Maintenance, ultrasound will help you stop problems before they develop into catastrophic, costly failures through the data that it provides.
Here are some key reasons why ultrasound works so well in industrial environments:
At HECO, our Predictive Service Group (HECO PSG) provides on-site maintenance and reliability services for industrial facilities like yours. PSG can help you set up and run your PdM programs (PdM) and perform the necessary corrective actions that are revealed by data. Our team of engineers and technicians are both knowledgeable and experienced in a wide variety of equipment and technologies -- including ultrasound. In fact, we have a certified ultrasound technician for both air leak and steam trap surveys on staff. If you are ready to harness the potential of ultrasound for your facility, give us a call!
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