Qsonica Sonicator Q500 Operation Manual page 9

increases (increased load on the probe), additional power will be delivered by the power supply to
ensure that the excursion at the probe tip remains constant. The displayed wattage readings will
vary as the load changes, however the amplitude will remain the same.
The resistance to the movement of the probe determines how much power will be delivered to
maintain amplitude. For example, a ½" probe at 100% amplitude will require approximately 5
watts to operate in air. The amplitude of this probe is approximately 120um. Insert the probe in
water and the wattage reading will increase to approximately 90 watts. The wattage required to
operate the probe will increase as the load increases but the amplitude remains the same.
The amplitude control allows the ultrasonic vibrations at the probe tip to be set to any desired
level. Although the degree of cavitation/ultrasonic energy required to process the sample can
readily be determined by visual observation, the amount of power required cannot be
predetermined. A sensing network continuously monitors the output requirements, and
automatically adjusts the power to maintain the amplitude at the preselected level. The greater
the resistance to the movement of the probe due to higher viscosity, deeper immersion of the
probe into the sample, larger probe diameter or higher pressure, the greater the amount of power
that will be delivered to the probe. Setting the Amplitude control to its maximum will not cause the
maximum power rating of the unit to be delivered to the sample. The maximum power (500 watts)
that the Ultrasonic Processor is capable of delivering will only be delivered when the resistance to
the movement of the probe is high enough to draw maximum wattage.
It is the intensity of cavitation that measures the effectiveness of the sonication, not the total
power applied to the system. Intensity is directly related to the amplitude of the radiating face of
the tip or horn. It is amplitude that must be provided, maintained, and monitored. The unit
provides controlled amplitude under varying load conditions in order to give reproducible results.
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