Stirrer Shaft Speed
Those tests have shown that it is not possible to state a maximum RPM but the range in which the shafts vibrate heavily. Such vibrations are caused by resonance. Due to those vibrations the bearings of the agitator are exposed to high stresses and in worst case accidents can be caused by tipping over agitators. The use of liquids as medium can reduce vibrations, worn out agitator bearings or insufficient stability of the agitator support increase vibrations. In practice, the "critical RPM" should simply be avoided by either staying below or skipping quickly this "critical RPM range" to obtain a quiet running stirrer shaft. In general: the longer a stirrer shaft is, the larger its diameter should be.
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