Factors To Consider in Choosing Ultrasonic Cleaning Solutions

Ultrasonic cleaners work on the principle of cavitation. This refers to a process wherein very high frequency ultrasound waves, produced by a piezoelectric transducer, agitate a cleaning solution to emit millions of tiny vacuum bubbles that lift off dirt, grime and other impurities from any plastic or metal object placed in the solution.

The type, consistency and concentration of the cleaning solution depend on what you want to clean. Know that ultrasonic cleaners have a wide range of applications; ranging from household items to surgical instruments to guns to machine parts – and so many more. So it is important to choose the appropriate cleaning liquid, mixing it with water or aqueous or solvent-based solution, and then heating it to the right temperature. Then again, the objects to be cleaned, the type of contaminants to be removed and the degree of cleanliness required will often define the appropriate cleaning process. Contaminants, often referred to as soil, can be broadly classified into organic and inorganic. Grease, oil and wax are classified as organic soils; while oxides, salts and dust are inorganic.

For organic contaminants, the ultrasonic cleaning solution to be used should be aqueous. Aqueous cleaners comprise a detergent which adheres with the dirt, grease, or other particulate impurities and, coupled with the mechanical performance of the ultrasonic waves, lift off the resulting new amalgam into the solution. Alkaline detergents and fatty acids also react to blend the dirt into the solution. The dirt is dispersed into tiny particles; and the contaminants are flushed away by the mechanical action of the cleaning system, one tiny microscopic layer by layer. This process is called saponification.

Aqueous solutions are able to to reduce the cohesion of the water in which they are combined. For some cleaning applications, a solution of de-ionized water is enough to attain the desired result.

Typically, solvents are used in some applications. Solvent cleaners are usually much denser than water and have a lower surface-tension. The action of solvents work to dissolve the impurity. Because the solution has very low surface tension, it can penetrate the smallest of cavities and blind holes. Plus, it can dissolve contaminants like organic oils and others. Solvent cleaners are most appropriate for inorganic contaminants. Depending on the application, these cleaners can be a mixture of the solvent itself and water. A solvent can also be a blend or an azeotrope. This is a solution of two or more substances that after distillation, retains the same composition in the vapor state as in the liquid state.

Some solvents can be harmful to skin, so you must be careful in handling them. For example, solvents used to remove scale from objects are generally acidic. Moreover being more dense than water more ultrasonic power will be required to cause cavitation. Always be careful to select the appropriate solvent for a particular type of soil. In response to environmental management, HFC solvents, containing hydrogen, fluorine, and carbon are a good choice since they are non ozone depleting. Sometimes, flammable solvents such as turpines, isopropyl, and ethers can also be used. However, it is recommended to first double check with the manufacturer or vendor. Flammable solvents may require expensive modifications to the ultrasonic cleaner tank.


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