What is Speedsafe?

The way most traditional magnetic stirrers is essentially by having a spinning magnet in a box with a plate on the top, on which ypu place your beaker. you then put your stir bar inside the beaker and turn it on. This works fine, but if the beaker is removed before the magnet has stopped spinning, then the magnet has nothing resisting it and therfore the motor speeds up, potentially very detrimental to the stirrer. Similarly, if the beaker is then placed back onto the stirrer, the stir bar goes from stationary to full speed straight away, causing it to hurtle around the beaker. Again, this sudden added stress on the motor is detrimental.

Each Hanna stirrer is equiped with a speed sensing device (opto-sensor) coupled with a frequency voltage converter (FVC), which monitors the speed. As the speed reaches a preset maximum level, the speed limiter shuts down the VCO (voltage controlled oscillator) to slow down the motor speed. This ensures that when the load is suddenly removed from the stirrer, the motor will not accelerate to such a high speed that is hazardous to the stirrer.

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