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What makes airborne ultrasound so effective?

All operating equipment and most of the leakage problems produce a broad range of sound. The ultrasonic components with high-frequency sounds are extremely short waves in nature. A shortwave signal tends to be pretty directional. (condition monitoring)

As a result, isolating these signals from background plant and operational equipment sounds makes determining their precise position relatively simple. Furthermore, as mechanical equipment begins to alter, ultrasound’s delicate, directed character allows these possible warning signs to be noticed early, before an actual breakdown, and frequently before they are identified by vibration or infrared. (condition monitoring )

Although condition monitoring is necessary to evaluate the intensity and examine sonic patterns, it is also required to be able to “hear” the ultrasounds produced by various pieces of equipment. That is precisely why these instruments are so popular.

Condition monitoring enables inspectors to validate a diagnosis on the spot by clearly distinguishing between various equipment noises. Most ultrasonic devices achieve this using an electrical process known as “heterodyning,” which precisely transforms the ultrasounds received by the instrument into the audible range, where users can hear and distinguish them through headphones. (condition monitoring )

Condition Monitoring- the detailed process

Vibration analysis, infrared, and other technologies have long been used for condition monitoring and predictive maintenance. However, ultrasonic technology is a fantastic choice, particularly for enterprises with limited resources.

Friction, collision, turbulence, and electrical discharge all-cause ultrasound. In addition, mechanical equipment produces friction and impact as byproducts. A roller bearing, for example, generates friction when the shaft and balls move around the centre. However, if there is too much friction, issues with the equipment begin to emerge owing to unbalance, or the bearing may seize, resulting in the machine being shut down entirely.

It is crucial to keep important bearings lubricated at all times. An ultrasonic receiver whose microphone may be placed in touch with the housing will detect a smooth-rolling ultrasound produced by an adequately greased bearing. (condition monitoring )

When the bearing is over-lubricated, there is very little ultrasound audible via the headset during condition monitoring. If the bearing is under-lubricated, the intensity of the bearing will increase drastically, and additional noises, such as fluttering or scratchiness, may be created. Ultrasound will identify signs of an under-lubricated bearing long before infrared can detect heat rises and much before vibration analysis.

Furthermore, as a bearing wears out, the ultrasonic wave produces enormous spikes in the signal created by flat patches or scratches on the race. The tips are audible through the headset as pops or crackles. When the bearing’s ultrasound shows these characteristics, a replacement may be arranged during a routine production stoppage. Wear detection is immediate. It is not essential to obtain bearing readings from many contact points along different axes and send the results elsewhere for examination during condition monitoring.

However, the use of ultrasound technology for condition monitoring does not have to be complicated. The output of the ultrasonic sensor may be recorded using the software. Once a component’s baseline or benchmark signal has been obtained, subsequent recordings can be compared to it to assess its wear or correct lubrication over time.

The primary advantages of ultrasound and ultrasonic instruments in condition monitoring are:

1. They are directional and can be easily located.
2. They provide the earliest warning of impending mechanical failure.
3. Many problems are only detectable in the ultrasonic range.
4. Audible noise is ignored, increasing the selectivity of the ability to pinpoint. Therefore, they are more accurate at identifying problems.
5. They can be used to locate leaks and potential electric failure conditions.
6. Instruments can be used in loud, noisy environments.
7. They support and enhance other predictive maintenance (PdM) technologies or stand on their own in a maintenance program.
8. They are instantaneous in inferring diagnosis.
9. Isolation of faulty components, even internally, is possible.
10. More versatile – Ultrasound can be used for several applications.
11. Non-destructive – Ultrasonic instruments do not adversely affect or interfere with the component under test.
12. Ultrasonic testing can be performed while the equipment is operating.
13. Maintenance personnel currently using IRD can easily use this equipment.
14. They can detect even airborne sound waves from the equipment and many motor NDE bearings.

Instrumentation

The use of ultrasound technology for health monitoring, on the other hand, does not have to be complicated. The ultrasonic sensor’s output can be captured using the software. After obtaining a component’s baseline or benchmark signal, future recordings can be compared to it to measure its wear or correct lubrication over time.

Some devices allow you to change the frequency response from 20 to 100 kilohertz (kHz). In addition, analogue or digital ultrasound equipment is available. Decibels are used to represent the intensity of a signal on a digital instrument. In general, digital instruments incorporate onboard data logging with data management software to offer trending information and set warning groups for equipment that requires special attention. Some digital instruments also offer onboard sound recording, allowing users to capture sound samples and analyze them using spectrum analysis software.

Applications

Ultrasonic translator applications are classified into three categories: mechanical inspection, leak detection, and electrical inspection.

Mechanical inspection

While functioning correctly, mechanical equipment emits a “normal” sound characteristic. As components begin to deteriorate, the original sound signature changes. This change can be detected as a change in the intensity of a display panel or as a qualitative sound change that can be heard through headphones and recorded for later study. An ultrasonic translator can be linked to a vibration analyzer, or sound samples can be analyzed on a personal computer using spectrum analysis software.

“Ultrasonic monitoring of bearings offers the earliest warning of bearing breakdown,” according to a NASA study. They discovered that a 12-decibel rise in amplitude of a measured ultrasonic frequency over baseline indicated the early (incipient) phases of bearing failure. This shift is sensed long before changes in vibration or temperature reflect it.”

Other ultrasonic mechanical examination opportunities include mentioning a few, cavitation in pumps, compressor valve leakage, broken gears, excessive rubbing, and weak connections.

Leak detection

Ultrasound is helpful because it can detect the sound of a leak. When a fluid (liquid or gas) leaks, it flows from the high-pressure side to the low-pressure side, where it expands rapidly and creates a turbulent flow. This turbulence contains a lot of ultrasonic energy. As a result, the strength of the ultrasonic sound decreases fast further from the source. As a result, the exact location of a leak may be determined. This can apply to pressure leaks such as pressurized air and negative pressure (vacuum) leaks and leaks in valves and steam traps.

Lubrication

As the notion of “predictive” lubrication vs time-based (“preventive”) lubrication has arisen, there are situations when spectral analysis mixed with sound might be beneficial. For example, instead of lubricating bearings on a regular, “time-based” schedule, inspectors can test bearings regularly and identify those that require lubrication while leaving the rest alone. In addition, lubrication technicians can be trained to apply just enough lubricant to avoid over-lubrication in this manner.

When a bearing exceeds a baseline by 8 dB without affecting acoustic quality, it should be oiled. The technician should cease adding lubricant when the sound level has decreased to the preset baseline level. Viewing a good picture while monitoring amplitude changes and listening to acoustic qualities in real-time is one technique to show this process. (condition monitoring)

Spectral analysis software

A similar FFT diagnostic may now be conducted on a conventional PC with the release of spectrum analysis software, as long as the PC has a sound card. These apps give spectrum and time series representations of sound and allow users to hear sound samples while viewing them on a PC monitor.

A sound sample is often recorded with an MP3 recorder or a tape recorder. Some ultrasonic devices offer onboard sound recording capabilities that may be transferred to a PC via a compact flash card. Acoustic qualities may be examined when the recording is played again in real-time. An anomaly can be easily detected based on a known “good” or “normal” state.