Ultrasound is a mechanical wave with frequencies above the perceptible range of audibility for airborne sound of about 16 Hz to 16 kHz which in its propagation is linked to an elastic medium.
| Infrasound | 0 Hz < f < 20 Hz |
| Audible sound | 16 Hz < f < 20 kHz |
| Ultrasound | 16 kHz < f < 1 GHz |
| Hypersound | f > 500 MHz |
1 Hz = 1 undulation per second = 1 Hertz
In liquid media ultrasound propagates in form of a longitudinal wave. Due to sound pressure there will be compressions and depressions. Tensile forces during the suction phase of the depression can "tear" the fluid; this results in the formation of microscopic bubbles which are filling with air and/or liquid vapour (cavitation).
With the imploding of those cavitation bubbles dirt particles are really "blasted off" from the surface of the instruments and suspend into the liquid.
Cavitation is the main reason for the cleaning effect in low-frequency ultrasonic cleaning. Its cleaning action can be best compared with scores of microbrushes. Smallest and hardly accessible places such as lumens, corners, or undercuts especially will be advantageously reached.
Example (MPEG 2 file)
Advantages of the ultrasonic treatment
• improved cleaning effect
• intensive and gentle for the instruments
• no rests of dirt in pits and pores
• no damage of instrument surfaces
• short time contact of the instruments and the disinfectant and cleaning agent - no risk of corrosion
• ecological through:
- reusability of the disinfectant and cleaning agent
- biodegradable disinfectant and cleaning agent
- energy saving
• economic through:
- short machining time
- low costs for energy, water and disinfectant and cleaning agent
• easy and safe handling