Labnet AccuPlate Hotplates, Stirrers and Hotplate Stirrers User Manual
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Frequently Asked Questions
I have a beaker of water on my hot plate and set the temperature for 550°C. Why
does the display setting blink and not remain constant?
The display will blink at any time when the temperature sensor is not within range of the
set temperature value. The temperature measured by the sensor is a composite of the
temperature of the heating element located beneath the sensor, the ceramic top above
the sensor, and the very small air space around the sensor. Water requires a substantial
amount of heat in order to boil yet remains at a constant temperature of 100°C for the
duration of the boiling process. Although the heating element is producing maximum heat
at the 550°C setting, the water consumes this heat so quickly during the boiling process
that the heat is unable to raise the temperature measured by the sensor to within range
of the 550°C set value.
How long does it take to bring a beaker of water to boil?
Using a 600 mL PYREX® beaker with 400 mL of water at 25°C, it takes approximately 15
minutes to bring the water to a full, rolling boil.
Can I use a metal tray on top of my Labnet hot plate?
No. The metal will act as a heat sink, and have a high probability of creating an abnormal
heating condition. If an abnormal condition is detected, the product will shut down. A
metal vessel will also scratch the ceramic top plate.
The stir bar keeps decoupling. Why and what can I do to stop this?
These units are programmed to minimize decoupling. However, liquid viscosity, stir bar
magnetic strength, vessel used, and speed changes can cause decoupling. High
viscosity liquids must be stirred at slower speed settings. The magnetic strength of stir
bars can weaken over time and may need to be replaced. Vessels used need to have
thin, flat bottoms to insure optimal performance. Rapid decreases in stir speed can cause
decoupling as the magnet slows down quicker than the stir bar and the liquid.
What size vessel should I use?
Vessels used on the top of a hot plate must not be larger than the top plate.