Gas removal by ultrasonics
For good sonic wave propagation, the elimination of gases dissolved in cleaning liquids is indispensable.
In the washing liquid which has just been poured into the tank, and in which the detergent has dissolved, or when the temperature is too low compared to that of the speed, air is present in the form of numerous gaseous bubbles.
These are obstacles to the good propagation of the waves generated by the PZT transducers.
This is due to the fact that the speed of sound is directly proportional to the density of the medium in which it propagates: for example, in steel it is 5,000 metres/sec, in water it is 1,000 metres/sec, and in the air it is 330 metres/sec. Then our sound wave, which travels in the washing liquid at 1,000 metres / sec, slows down when it encounters an air bubble and then deviates. If it immediately meets another air bubble deviates once again, until it comes back if the air bubbles are closely packed together.
In conclusion, to achieve the best result with ultrasonic cleaning, the liquid must be released quickly released from the air dissolved in it (degassing).
With ultrasonic cleaning systems, degassing occurs spontaneously, but requires a certain period of time (10-15 minutes with hot liquids).
To accelerate this process, our generators have a special function called DEGASSING, for which, and for short periods of time, composite wave trains are generated in multiple frequencies.
In this way, the release of the air is accelerated throughout the volume of the tank and the ultrasonic effect soon reaches maximum efficiency.
Ultrasonic cleaners are excellent at degasification
SONIFICATION
In chemistry, degassing is the process that leads to the removal of dissolved gases in liquids (typically water or aqueous solutions).
Degassing may be required for various reasons: for example, it may be carried out when a solvent free of air or oxygen is required to prevent unwanted reactions with the solute, or to avoid the formation of bubbles in a liquid which must later be solidified (the presence of the bubbles affects the mechanical properties of the material).
Ultrasonic degassing has often been used for this purpose in many processes in the pharmaceutical industry and chemistry, in general.
In fact, the solubility of gases in liquids is determined by Henry’s law which states that the amount of dissolved gas is proportional to its partial pressure in the gas phase. Therefore, the decrease in pressure created by the ultrasonic waves results in the decreased solubility of the gas.
This phenomenon is called sonication, or more accurately sonification.
Our cleaning devices have also proved to be highly useful for degassing. We have applied submersible transducers directly in the mixing tanks with truly exciting results.
Application of ultrasonic transducers in the food industry
A new trend is spreading throughout the food industry:
the reduced use of heat treatments for the purpose of preserving all the nutritional and organoleptic characteristics of food products
The conservation of foods is based on methods and techniques whose purpose is to slow down or stop their natural process of alteration, keeping their microbial load under control or destroying it
Food conservation techniques, whatever method is used, have the common objective of creating an environment which is unfavourable to the life, development and activities of microorganisms.
Sonication, which has the same principle for use as ultrasound, is among these technical innovations.
