Magnetic 2.5L auto-reverse stirrer with tachometer, stainless steel cover, 110/115V, When stirring a solution, to work with a constant speed (Revolutions Per Minute) is an important factor in ensuring that the best repeatability in test and processes is achieved. Without a tachometer, there is no way of knowing the RPMs. HI 304N is a heavy-duty stirrer with a built-in tachometer.
It is often desirable to stir in two directions in order to achieve maximum homogeneity. An advanced circuit allows HI 304N to reverse the direction of the stirring at user selected intervals. The interval can be adjusted from 30 seconds up to 3 minutes. In addition to the tachometer and precision speed control, a limiter will assure that the maximum speed is never exceeded (Speedsafe). Often, a sample is removed from the stirrer before the speed has been reduced. In some cases this has caused the stirrer to accelerate until it destroys itself. HANNA stirrers incorporate a VCO device that will stop the motor from accelerating as soon as the load is removed.