Theory Of Operation - Omni PCR-258 User Manual

SECTION 3 — OMNI TH OPERATION

3.5 THEORY OF OPERATION

The rotor shaft is coupled directly to the drive motor, via the drive pin.
When attached to the homogenizer motor, the rotor shaft can spin
up to 35,000rpm. This assembly makes up the rotor portion of the
rotor-stator generator probe. The tube/collar assembly is attached to
the motor housing, but does not spin. This is the stator portion of the
rotor-stator generator probe. As the rotor knife spins within the tube
and collar assembly, it creates a pumping action, pulling the sample
into the open end of the generator probe and forcing the sample out
through the windows in the tube. The interaction of the rotor knife
with these windows sets up a shearing action, reducing the particle
size of the sample. The speed differential between the rapidly moving
portion and the relatively stationary portion of the sample sets up a
second force called cavitation which pulls the sample apart, further
reducing the particle size.
The processing efficiency can be affected by:
• Amount of material processed vs. size and speed of the
generator probe.
• Container geometry and size (round vessels encourage
swirling, while fluted or cornered vessels disrupt flow patterns
for more effective mixing/processing).
• Processing speed vs. optimal speed.
• Size and type of material and flow characteristics (material
particles must be small enough to be carried into the
generator head for optimal processing).
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