Air and other gases contained in a freshly filled ultrasonic cleaning bath interfere with the cleaning performance of the ultrasonic cleaner. Evidence of these gases can be seen as bubbles that form on the inside of a standing glass of warm water. Ultrasonic cleaning is accomplished by the energy released from the violent collapse of tiny vacuum-filled bubbles. Air bubbles and dissolved air in the cleaning liquid absorb ultrasonic energy and inhibit the implosion of these cavitation bubbles, significantly reducing the cleaning effect.
Air can also be introduced as bubbles clinging to objects immersed in the ultrasonic bath.
Entrapped air can be removed two ways. Simply by running the ultrasonic cleaner a “degassing” occurs as heat and cavitation drive the air to the surface in the form of bubbles. If products to be cleaned are in the ultrasonic tank during this operation, the cleaning process is lengthened because a portion of the ultrasonic energy is diverted to the degassing operation.
A more practical and energy-efficient solution is to use an ultrasonic cleaner equipped with a degas function and carry out the process in advance of ultrasonic cleaning operations. A degas mode accelerates the removal of gas contained in cleaning solutions by pulsing, or introducing short breaks in the ultrasonic operating cycle which allows coalesced gas bubbles to rise to the surface and burst.
A degassing operation in degas mode usually lasts about 10 minutes, but depends on several factors. These include the amount of gas in the liquid, the volume of liquid being degassed, and the ultrasonic power employed.
In summary a degas mode available in certain ultrasonic cleaners such as manufactured by Elma greatly increases the speed of the degassing operation. This allows normal operations to start within 10 minutes rather than using ultrasonic cleaning action to accomplish degassing of fresh cleaning fluid. If an ultrasonic cleaner does not have a degas feature, each time the tank is filled with fresh solution the degassing effect can add 30 minutes or more to the cleaning cycle. When a shop or lab uses a set cleaning cycle time for a specific application, it is imperative to degas the fresh solution before the cleaning process begins or the cycle time will be lengthened each time the tank is refilled.
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How do you degas your ultrasonic cleaning solutions?
