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electronic GmbH & Co. KG • Heinrichstraße 3-4 • 12207 Berlin • Deutschland • [email protected]
6.1.4 Check the cooling
• Insert a commercially available wattmeter between the mains plug of the ultrasonic bath
and the socket
• Fill the ultrasonic bath with liquid, see chapter 4.1.
• Switch on the ultrasonic bath, leave the ultrasound switched o
ff
• Switch on cooling for a short time (target temperature must be set at least 1 degree
above actual temperature)
• Read
o
ff
the measured value displayed on the wattmeter and note it down
• Switch cooling on again (set the target temperature at least 1 degree below actual
temperature)
• Wait for the refrigeration unit to restart for 2 minutes
• Read
o
ff
the measured value displayed on the wattmeter and note it down
• Compute the di
ff
erence between the two measured values
• Switch
o
ff
the ultrasonic bath
The measured value read cooling switched on must be approx. 100-200 W above
the measured value when cooling is o
ff
6.1.5
Checking the ultrasound e
ff
ect
To check the ultrasound e
ff
ect, it is recommended that a foil test be carried out both
on initial commissioning and at regular intervals thereafter. The frequency of testing is
the responsibility of the user.
The foil test is a simple procedure for demonstrating the intensity and distribution of
cavitation in an ultrasonic bath. For this purpose, an aluminium foil stretched on a foil test
frame is inserted – in this case without foil test frame in the inset beakers intended for this
purpose. The aluminium foil is perforated or destroyed to a certain extent by cavitation,
depending on the duration involved.
For purposes of reproducibility, it is important that the test conditions
remain constant:
• Filling height of the ultrasonic bath (2/3) and in the sample vessel
• Temperature of the tank contents
• Where applicable: degassing time (degassing for 10 mins. before the test)
• Foil properties (thickness, surface)
• Positioning of foil
• Sonication
time
• Concentration and type of ultrasound preparation
Foils can be archived in a suitable way (scanning, photos, etc.). This allows the foils to
be compared at any time. The perforated areas of all foils should have approx. the same
dimensions and distribution – even if the results are never identical.
A process validation, e.g. for the treatment of medical products, can only be achieved by
conducting regular foil tests.
Film: http://bandelin.com/folientest/.
In order to obtain a su
ffi
ciently strong cavitation e
ff
ect, the foil test also requires the surface
tension of the water used to be reduced using surfactant preparations (in the ultrasound