Ultrasonic cleaners supply an exquisite alternative to traditional 'immerse, soak and scrub' methods of cleaning parts and objects. While intensified cleaning is its key advantage, it does have the side consequent of raising temperatures steadily across a cleaning run. Sure objects intended for cleaning are made of delicate materials that are sensitive to both higher temperatures as well as large variations in temperature. A good temperature regulation law is required for this.
Ultrasonic cleaners use a transducer to originate ultrasonic waves within the solvent medium. These waves cause 'cold boiling' at points on the liquid-solid object surface. This forms a covering field of vapor microbubbles that rapidly cool and condense-collapse in a process called cavitation. The rapidly collapsing or imploding microbubbles produce localized shock waves that cause this intense cleaning action.
The law of conservation of vigor requires that all the vigor - external thermal heating and ultrasonic - added to the solvent-object law be dissipated as internal thermal vigor and unit heat loss. This consequent causes solvent heating at rates depending on the solvent type, unit heat loss, transducer frequency, efficiency and power rating. Selection of the base operating frequency and solvent is largely a function of the material of the object for cleaning and the cleaning chemistry.
Each combination of solvent, impurities and material of the object to clean requires an ideal or optimal operating temperature. In most applications, this temperature is above ambient - often in the range of 40 to 60 degrees Celsius - and needs to be sustained within a band of a few degrees. In many cases, the net consequent of a heater with a temperature regulator and heat loss to the surroundings is adequate for temperature control within an thorough range. Some materials for cleaning may be more thermally sensitive than others are, and need greater cooling to keep the temperature relatively low. In such cases, a cooling-water coil firmly affixed to the tank supplies the desired cooling. A fixed flow-rate cooling coil with an thorough heat change area is dipped into the solvent to lower the temperature, while using partial control with the heater alone for temperature regulation. Examples of thermally sensitive materials contain dental prosthetics and cleaning proteinic impurities.
The cooling-water coil is a straightforward auxiliary device that is most sufficient in producing the lower temperatures required for some ultrasonic cleaning applications. This coil accessory is included in Elmasonic S ultrasonic cleaners. A few precautions are all it takes for its allowable use. The material of the coil must be as corrosion unyielding as the cleaner's components - typically, the same stainless steel type is used. The thermal area and water flow-rate of the cooling coil must be calculated and verified. This requires elementary heat balances for a single solvent volume, operation, solvent type and cooling load of the ultrasonic cleaning application. Excessive cooling can lead to condensation inside the transducer module, which may cause electrical or electronic short-circuiting. allowable Selection of the cooling coil area, cooling water flowrate and good heater-based temperature control is adequate to prevent this. Finally, the cooling coil needs cleaning and drying after each use.
