Acoustic Cleaning - Basic concept
|
All the Acoustic Units belonging NIRAEUS® Acoustic System generates a sound wave shape within a safe field range (60÷300 Hz) Note 1Such safe range it’s defined “audiosonic”, absolutely different from other dangerous known systems like “infrasound” Note 2 or not efficient in our industrial target like “ultrasound” Note 3 |
||
|
Note 1 Safe field of the audiosonic frequencies tested and approved by E.P.R.I. (Energy Power Research Institute – USA), who has fixed the lowest limit for the industrial application, at 20 Hz. |
||
|
Note 2 Infrasound is sound with a frequency too low to be detected by the human ear. The study of such sound waves is sometimes referred to as infrasonics, covering sounds from the lower limit of human hearing (about 16 or 17 Hz) down to 0.001 Hz. This frequency range is the same one that seismographs use for monitoring earthquakes. Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation. |
||
|
Note 3 Ultrasound is a cyclic sound pressure with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kHz (20.000 hertz).Ultrasonic cleaners, sometimes mistakenly called supersonic cleaners, are used at frequencies from 20-40 kHz for jewellery, lenses and other optical parts, watches, dental instruments, surgical instruments and industrial parts. An ultrasonic cleaner works mostly by energy released from the collapse of millions of microscopic cavitations near the dirty surface. The bubbles formed by cavitation collapse forming tiny jets directed at the surface. |
||
| Industrial Acoustic Cleaning is the use of low frequency, high-power sound waves to excite and dislodge particulate deposits from structural surfaces. Sound is transmitted through the movement of particles in a gassous medium, such as fluegas / exhaust / air. Cleaning energy is transferred through a series of compression and tension cycles that create movement in the gassous medium to fluidize dust particles that have collected on various surfaces. The acoustic disturbance can be represented as a wave, with the X axis representing time, and the Y axis the displacement of a given particle in the medium from its rest position. Once the particulate has been displaced, it is removed by gravity and/or gas flow. | ||
|
Hertz and decibels The sound we hear is described by its frequency. Frequency is measured in hertz (Hz), or cycles per second. The general range of hearing humans can detect is between 20 Hz and 20 kHz. The fundamental measurement of loudness is the "BEL" named for A. G. Bell. The decibel (dB) is 1/10 of a BEL. The decibel is a logarithmic scale of acoustic pressure. In the measurement of sound, the focus is on amplitude of the acoustic pressure, measured in Pascals (Pa) and/or dB. Increasing of 10 dB represents a 10-fold increasing in sound pressure. |
||
|
Fundamental Frequency for Cleaning
Acoustic cleaners dislodge particulate by vibrating the particles with sound energy. A certain sound intensity (dB) at a given frequency is required to fluidize particulate. Less intensity (dB) is required to resonate particles at lower frequencies (60 Hz to 300 Hz) Larger wavelengths are produced at the fundamental frequencies of 60 Hz to 300 Hz Thus, an Acoustic Unit that produces an intensity level of 150 dB with a fundamental frequency of 100 Hz can clean a substantially larger area than an Acoustic Unit that generates similar intensity levels (dB) at a fundamental frequency of 250 Hz. Lower Frequency = Greater Effective Cleaning Area
|
||
