These units are heavy-duty stirrers, and can stir up to 5.0 liters (1.3 gallons), making them ideal for laboratory and production use. Each model incorporates electronic controls that allow the user to precisely regulate the speed, and a limiter ensures 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 can cause the motor 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.

 

In addition, HI322N and HI324N have an automatic feedback feature with HI324N also boasting an LCD tachometer. The motor is electronically controlled to maintain the chosen speed even if the load changes. If the viscosity or the level (fluid weight) increases or decreases, the circuitry will adjust the output power. The RPM display guarantees repeatability in QC test and research by constantly displaying the RPMs.