Degassing is term used to describe the removal of dissolved gasses from a liquid in an ultrasonic cleaning tank.  Dissolved gasses will reduce the effectiveness and power of an ultrasonic cleaner since these gasses provide a cushioning effect on the ultrasonic waves generated.  However, the dissolved gasses within the fluid are largely removed in the first few minutes of ultrasonic activity.  Therefore, in most cases, ultrasonic cleaners can be used immediately after changing cleaning fluids.

When an ultrasonic cleaner is activated after a fresh batch of cleaning fluid has been added, one will notice a huge veil of very fine bubbles rising to the surface from every area of the cleaning fluid.  The audible sound generated by the ultrasonic system is also deadened at this time, and the system does not produce the typical sound that the ultrasonic cleaner will produce when the fluid is degassed.  Once the veil of bubbles rises to the surface, sound begins to increase in volume, and ultrasonic surface activity begins to generate.  At this point, the ultrasonic cleaning system is capable of ultrasonic cleaning at 85% or more, enough power to remove the contaminants in question.  In fact, if the ultrasonic cleaning system can NOT remove the contaminant at 85% efficiency, chances are that the ultrasonic cleaning system does not have enough power for the application in the first place. 

The above information is the primary reason why Zenith ultrasonic generators do not include degassing controls which pulse generator output on and off to permit bubbles which are created during the degassing process to rise to the surface of the fluid.  This circuit adds complexity and parts to the equipment design, and adds new controls that are rarely touched or used in reality.  Operators simply fill the tank, activate the ultrasonic system for a few minutes, and begin cleaning.

The only time that degassing for extended periods may be required is on very large ultrasonic cleaning tanks with liquid capacities over 100 gallons.  These tanks may require more than a few minutes to generate effective ultrasonic cleaning activity.  The use of degassing controls, however, will not decrease the wait time when compared to a system that operates continuously.

Degassing takes place at a faster rate with increasing ultrasonic frequencies.  Since higher frequency ultrasonics, such as our 80kHz system, produce more evenly distributed cavitation, a larger volume of liquid is being attacked ultrasonically per unit of time.  As a result, higher frequencies tend to degas faster than lower frequencies.

Once a fluid is degassed by ultrasonic activity, or heating of the cleaning fluid, it does not need to be degassed again.  Therefore, degassing is only an issue when cleaning fluids are exchanged with new fluid.  Pumping of a degassed fluid does not reduce its efficiency as demonstrated by our Ultramatic  and Ultramatic HV Systems which pump cleaning and rinsing fluids during operation, with no reduction in the effectiveness of the ultrasonic cleaning or rinsing processes.  However, cleaning fluids should not be circulated during the ultrasonic cleaning process, since circulation will impede the effectiveness of the ultrasonic cleaning system.  More information on how circulation affects the ultrasonic process can be found in the Ultrasonic College drop-down menu under "Fluid Circulation."

Degassing:

• Requires only a Few Minutes in Typical Ultrasonic Cleaning Systems
• Needs to be Addressed Only when Fresh Fluids are Added to the Ultrasonic Tank
• Will Take Longer in Larger Ultrasonic Tanks over 100 Gallons in Size.
• Is Performed Faster with Higher Operating Frequencies
• Is Not Required after Pumping of Fluids.

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Zenith Mfg. & Chemical Corp.
85 Oak St.
Norwood, NJ  07648-0412
800-432-SONIC (7664)
201-768-6999
sales@zenith-ultrasonics.com