ULTRASOUND RESOURCE LIBRARY

With Arcing, the discharge to ground is a high current pathway across an insulator.

This is a “burst of energy” that has a long duration discharge.

The “buzzing” Sound that is heard with corona and the initial stages of tracking is not heard with arcing.

The “burst of energy” will be seen as wide peaks in the time series.

Corona is where the pathway to ground is through the air.

This discharge has a buzzing or frying sound that is uniform.

You will note the harmonic peaks are evenly distributed throughout the screen.

The amplitude peaks in the Time Series are equally spaced as the discharges only occur at the negative peak of the sine wave.

FFT View

Time Series View

Tracking occurs where there is a low current pathway to ground across an insulator.

There is a buildup and discharge of the voltage that produces “popping” sounds.

The discharge peaks correspond to the “popping” sounds. They are not uniformly spaced in time.

Note the evenly spaced harmonics with no frequency content between them in the FFT and the evenly spaced impacts which are almost “clones” of each other in the Time Series.

A very clear indication of mechanical looseness.

FFT View

Time Series View

This is another example of tracking.

Note the erratic energy bursts accompanied by a buzzing sound in the background.

FFT View

Time Series View

Note the lack of harmonics and the disappearance of the buzzing sounds typically heard in other forms of of tracking, seen in both the FFT and Time Series views.

FFT View

Time Series View

This is a typical transformer.

It is shown in the FFT screen and in the time series.

All transformers have their own distinct “hum” which can be used as a baseline to note any changes.

FFT View

Time Series View

This view of a transformer with loose winding.

Note the shrinking and growing pattern. The harmonics have no frequency content between them which indicates a mechanical issue.

FFT View

Time Series View

Listen to the full 14 seconds.

Note the standard transformer hum accompanied by two very distinct popping sounds.

Time Series View

Good Bearing:

FFT of a good bearing.

Since there are no defects, the sound will be a smooth rushing sound.

The spectral view will not show any harmonics or large peaks.

Bad Bearing:

This is an FFT spectrum view of a bad bearing. As a bearing enters the failure stage there is a rise in the decibel level of 12- 16 dB over a baseline. This rise in amplitude is usually accompanied by a change in the sound quality.

Note that on this bearing we can now observe fault frequency harmonics which we can use to confirm & analyze.

The integrated bearing fault calculator can confirm inner/outer ring, ball pass or cage defects.

This is a Time Series view of a bad slow speed bearing (less than 25 RPM).

The heterodyned audio signal we can listen to gives us already a clear indication of bad condition.

When analyzing slow speed bearings it may be difficult to get a good reading in FFT view.

However, the defects are very apparent in the Time Series view.

This is a Time Series view of a bearing being lubricated while listening with an Ultraprobe.

Lubrication should be added gradually.

Listen to the full 49 seconds to hear and view the gradual drop in amplitude as the lubricant is added.

This is a time series view of a bearing being over lubricated.

If too much lubrication is added the amplitude will rise. If this occurs, immediately stop adding lubricant.

Listen to the full 43 seconds to observe and hear the drop in amplitude and the rise in amplitude.

Steam is the vapor phase of water and is identified acoustically as a constant rushing sound as you will hear in this sample.

Good Inverted Bucket Steam Trap Time Series View

This trap will operate in an “open-close” cycle.

The number of cycles and the time between cycles is dependent on the condensate load and the size of the trap. Here is a typically “good” trap operation.

Inverted Bucket Steam Trap Stuck Open Time Series View

When the bucket loses its prime it sinks and forces the discharge valve open.

Acoustically the “open-close” pattern disappears and only a steady rushing sound of steam blowing through will be heard.

Good Thermodynamic Steam Trap Time Series View

A Thermodynamic or “Disc” trap will have an “open-close-open-close” cycle of anywhere from 4 to 10 times a minute.

Thermodynamic Steam Trap “Motorboating” (Leaking) Time Series View

In this sample the disc no longer shuts closed as it should. Instead it is leaking steam. This is heard as a chattering sound and can be observed in the time series view.

Thermodynamic Steam Trap Stuck Open Time Series View

If the disc is stuck open it will waste steam. The “open-close” pattern will be replaced with a constant rushing sound of steam blowing through.

Good Thermostatic Steam Trap Time Series View

This trap will operate in an “open-close” cycle.

As steam enters, the thermostatic element expands and the trap will close.

When the steam cools to condensate, the element will contract and open.

The number of cycles and the time between cycles is dependent on the condensate load.

It can discharge for long cycles or stay shut for a long time. Conversely it can also open and close rapidly.

Thermostatic Steam Trap Stuck Open Time Series View

Should the thermostatic element fail, the trap can be stuck open.

Acoustically the “open-close” pattern disappears and only a steady rushing sound of steam blowing through will be heard.

Good Float And Thermostatic Steam Trap Time Series View

A float and thermostatic trap has two elements: the ball float and the thermostatic bellows.

Typically this trap will have a steady modulating flow. This is caused by changes in the motion of the float element as it adjusts to changes in the condensate level.

Occasionally the thermostatic element will contract to discharge contaminants such as air.

Float And Thermostatic Steam Trap Stuck Open Time Series View

When a “F&T” trap fails it can fail shut or open.

If the ball float becomes damaged due to an event such as water hammer, the float will sink and shut the trap.

In this instance there will be no sound and the trap will be cold. If the valve is stuck open then steam will rush through.

This is an example of steam rushing through.

Good Reciprocating Compressor Valve Time Series View

The advantage of ultrasound spectral analysis is that the inspector can hear and see the sound sample as it plays.

Here is a typical good compressor valve. Note the distinct “open” “close” of the valve.

Bad Reciprocating Compressor Valve Time Series View

This is an example if a leaking reciprocating compressor valve.

It does not close as sharply as in the sample of the “Good” reciprocating valve.

You will also note the longer “open” segment in the time series.

This is an example of cavitation in a valve.

Cavitation is the formation and implosion of cavities in a liquid (similar to bubbles) usually on the low pressure side of a pump or valve.

Cavitation is a significant cause of wear (surface fatigue) that can lead to a failure condition.

The most common examples of this kind of wear are pump impellers and bends when a sudden change in the direction of liquid occurs.