Airborne Ultrasound
How DOES the Airborne ULTRASOUND EQUIPMENT WORK?
The analysis by ultrasound is a noninvasive technique that can be applied in various fields:
- Leak Detection of a fluid
- Inspection machines and ball bearings
- Electrical inspections
These analyzes are important as they allow to contain energy costs (losses and friction causing energy waste), increase the availability and safety of plant and machinery with obvious benefits on risk prevention and savings on insurance policies.
Ultrasounds are mechanical sound waves with frequencies above those audible to the human ear (20 kHz). The tools to Airborne Ultrasound, thanks to a piezoelectric sensor, turn the mechanical waves in electric waves. Thank un'eterodina, the wave frequency is lowered and the operator made audible through headphones or a recorder.
How do Airborne Ultrasound detect leak?
The losses of a generic fluid (gas or liquid) from a pipe at pressures other than environmental causes, if the rate of leakage is sufficient, a turbulent motion with a spontaneous formation of acoustic waves. The man can hardly pick up sound waves above the 14/15 kHz (people with an exceptional hearing come to feel a maximum of up to 20 kHz), especially if it is in a noisy environment. The probability that a human being is able to hear the sound originated from acoustic waves of weak intensity, generated by small losses, is practically zero even in a situation of complete silence. It follows that, in an industrial plant, the detection by ear of losses is a technique somewhat coarse and with a very low efficiency in detecting leaks.
On the other hand, if you leave the field of audible frequencies and enter the field of ultrasound (≥ 20 kHz), you have three fundamental advantages:
- With the appropriate tool you can perceive ultrasound generated by a very small loss;
- Ultrasound waves tend to propagate unidirectionally from the source that generates them, so it is able to accurately detect the loss;
- The noisy environment for the human ear can be pointed quiet or quieter when analyzed in the spectrum of ultrasound.
The following figure illustrates the above concepts, as you see the fluid flowing through the orifice creates a movement called "laminar" or "turbulent". This turbulence generates ultrasonic components that are detected by the tool operator and made audible through special headphones. Generally it is possible to observe that, as the greater the loss, the greater the level of ultrasound. The same phenomenon is created in the case of vacuum leaks, but takes place within the receptacle and can be detected by contacting it with the probe of the instrument Ultrasonic Airborne.
Consequently, with an ultrasonic detector as Ultraprobe® the detection of losses in circuits of compressed air or other gas becomes easy and fast, are installations in pressure or vacuum, because, in addition to determining the presence of loss, it is possible to locate the point Precise escape for an immediate intervention.
Obviously the tool is also applicable for the inspection of valves, steam traps, heat exchangers and potentially in any component in which a fluid flows.
All equipment Ultraprobe® detect ultrasonic signals to 40 kHz, with a bandwidth between 37 and 42 kHz, because in this range are detected ultrasound generated by the pressure of compressed air and other gases.
The signals, whose intensity in decibels is on the display, are made audible to the operator in the headset and are unmistakable, even in the presence of ambient noise different. Any ultrasound competitors can easily be shielded. Obviously the coach to exploit better the equipment must be trained and have the hours of field experience.
Inspection of rotating machines and ball bearings
Another important application of ultrasound in the field of maintenance is that relating to rotating machines and to ball bearings. Using the tools Ultraprobe analysis of such components is clear and effective.
The instrument is mounted a magnetic sensor that attaches to the machine and detect ultrasound analyzed through the "structure of the machinery" (inspections "Structure Borne"). In this way, after an analysis using software and a time series of data, you can understand:
- The causes of bearing failures;
- If politics lubrication of the bearing is correct or if you are in a state of ipolubrificazione (poor lubrication) or iperlubrificazione (excessive lubrication);
- The level of bearing wear.
In all these cases, the first alarm signal is due to the 'increased friction, which produces ultrasound initially and only later, when the damage is already present, begin to appear the vibration and debris detectable with oil analysis.
Better explaining the procedure of analysis to ultrasound it can be said that, in general, the mechanical movements produce a wide spectrum of sounds. Focusing on a narrow band of ultrasonic frequencies, Ultraprobe detects subtle changes in amplitude and sound quality. Such changes, such as establishing a NASA research, can provide an early warning to prevent a failure as any failure is characterized by a spectrum ultrasonic precise.
A very important aspect is therefore the possibility of a personalization of the bearing lubrication of critical machines, in fact the lubrication programmed not always is the best maintenance policy since a need of fat of a bearing can change depending on the environmental / operational, and then require a different amount of lubricant.
The importance of proper maintenance of the moving parts and bearings is also important from the point of view of energy as to have a lower friction implies a lower consumption of electricity.
Safety of electrical installations
Ultrasonic inspections are also useful in the departments of electrical maintenance, which generally perform routine checks of electrical panels, substations, transmission lines and high-voltage distribution lines. Given the increased attention to workplace safety and the dangers of flames and explosions arc, the ability to perform remote measurements ultrasound is extremely valuable. TV and radio interference are typical problems complained by telecommunications companies. Often the source of the trouble can be traced to a bad transformer or a malfunctioning switch. Determine the exact cause of the failure is fast and simple with a control ultrasound. The directional nature of ultrasound, addressed by a parabola, allows to detect any abnormalities maintaining a safe distance.
Moreover phenomena of electrical failure such as the electric arc, the tracking and the anomalies such as the corona effect and micro discharges produce the phenomenon of ionization of air molecules surrounding (which also generates ultrasound).
The instrument Ultraprobe detects high frequency sound produced from the air ionized and translates, through the phenomenon heterodyne, in the audible range. The sound quality for any type of issue is heard in the headphones, while the intensity of the signal is detected on the display.
You can then use ultrasound for the detection of faults and electrical faults because normally, the equipment is quiet, though, the processors can produce a constant ringing, which is easy to distinguish from the irregular sounds emitted by electric shocks.
WHY In our inspections DO we use only ultrasound Airborne?
Many inexpensive devices on the market are defined ultrasonic sensors but, to be honest, they are just plain noise amplifiers. It is relatively easy to build an electronic device that is able to detect ultrasound, while it is much more complex, and requires skills, experience and high costs, realize an electronic device that is able to only detect ultrasound of a certain frequency and so precise.
The advanced series Ultraprobe can eliminate all ultrasound "parasites", focusing only on ultrasound to analyze.
Condition monitoring operators, in addition to observing the precise level of ultrasound intensity at a given frequency, can, through the instruments of high level as the Ultraprobe 15000, listening to the sound quality made audible to the human ear, making the registration sound, store and manage the data but, above all, and this is the icing that makes the difference dell'Ultraprobe 15000, compared to all other existing devices in the world, are constantly reviewing the recorded sound in a very simple, because the instrument is able, via its screen on board, to immediately display the spectra.
Finally, we must point out that all the analyzes are done in factory running so you do not need to plan stops for inspections. Indeed the running of the plant is required so that the instrumentation can detect ultrasound in installations that still would not be generated.