This is the explanation for the dual UC's from a UC maker:
For the removal of coarse and tenacious contaminations and for pre-cleaning of robust surfaces such as stainless steel and cast iron we recommend cleaning at 25 kHz.
The most commonly used ultrasonic frequency range is 35-40 kHz for routine cleaning jobs and for cleaning jobs in the laboratory and sanitary sector.
For fine cleaning and for the cleaning of sensitive surfaces such as light metal alloys use an ultrasonic cleaner operating at 45 kHz.
Higher frequencies such as 130 kHz are used for fine cleaning jobs and for the cleaning of highly sensitive surfaces including micro electronics, printed circuit boards and precision optics.
For the removal of coarse and tenacious contaminations and for pre-cleaning of robust surfaces such as stainless steel and cast iron we recommend cleaning at 25 kHz.
The most commonly used ultrasonic frequency range is 35-40 kHz for routine cleaning jobs and for cleaning jobs in the laboratory and sanitary sector.
For fine cleaning and for the cleaning of sensitive surfaces such as light metal alloys use an ultrasonic cleaner operating at 45 kHz.
Higher frequencies such as 130 kHz are used for fine cleaning jobs and for the cleaning of highly sensitive surfaces including micro electronics, printed circuit boards and precision optics.

