V&P Scientific, Inc.
5
Technical Note 453
TUMBLE STIRRER OPERATION
The optimal operating speed of the Tumble Stirrer is dependent upon the particular application to be
used and needs to be empirically determined.
Factors to consider in determining optimal stir speed are the
application, fragility of the objects being stirred, size, shape, composition of the test tube, vial, bottle or
microplate well (glass, polypropylene or polystyrene), depth of the microplate wells, volume and viscosity of the
liquid, and the type of magnetic stir element (bar, disc, custom shape) used.
In general, stirring microbial cultures works best at low speeds. Stirring to resolubilize extracts, or to stir in deep
well microplates, requires high speed. The Tumble Stirrer is well suited for either of these types of applications
since it can function at minimum and high RPM. Again the speed of stirring needs to be determined empirically
for the application.
Most tumble stirring applications require a stir speed between 300
–
500 RPM. The VP 710U5 series is
capable of a maximum stirring speed of 800 RPM.
The Stirrer Control Unit has an ON/OFF Power Switch and a Speed Control Knob. The Stirrer Speed is manually
controlled by Speed Control Knob. The speed of stirring can also be pre-set and the power turned on and off.
Voltage Switch is set at factory to voltage requested by customer when ordered.
If voltage Switch is changed
by customer, the resulting damage to the Control Unit is not covered under the Stirrer warranty.
