Magnetic stirrers are devices widely used in laboratories consisting of a rotating magnet or a stationary electromagnet that creates a rotating magnetic field. This device is used to make a stir bar, immerse in a liquid, quickly spin for stirring or mixing a solution.
Magnetic stirrers generally include a coupled heating system for heating the liquid. They are one of the most handy instruments that we use everyday in our laboratory. Having one of them makes your life much easier in your laboratory.
If you start searching for magnetic stirrers the diversity of models and prices are very vast. You can find one for as low as ₹2,000 to high as ₹ 90,000. If you have never worked with a magnetic stirrer you will simply never know where to start.
This guide will help you by your search and purchase:
First thing you need to consider before purchasing your magnetic stirrer is the heating plate. There are magnetic stirrers with hot plate versions and magnetic stirrers without hot plate versions.
It is worth considering how often you’ll need a magnetic stirrer and hot plate before you indulge yourself with a system. Know your requirements, your daily procedures and necessities in your laboratory. If you hardly both heat and stir, then you can probably consider having a magnetic stirrer and a separate hot plate. If you have very little space and use both procedures simultaneously, then you can think about getting more in a combined form.
There are hot plates with a metal plate or a ceramic plate available and they usually heat up to 350 C (some models up to 500 C ) which is much higher than any temperature you’ll need in your laboratory. The basic models don’t have any temperature display and you’ll need a thermometer to check the temperature. Models with a digital temperature display are available as well.
When purchasing a magnetic stirrer with a hot plate, you obviously need to consider:
- The heat output (power/Watt of the hot plate)
- Heating range (look at the minimum heating temperature because the max. temperature is much higher than what you’ll need)
- Min. and max. adjustable temperature
The capacity of the stirrer is always mentioned for water. It is mentioned for the max. capacity: 2 lit for example. The nominal capacity is much higher than the real capacity because obviously you rarely will use plain water for stirring.
The speed is expressed as rpm (rotations per minute). The min. speed is about 100 rpm. powerful models have a speed of up to 2500 rpm. Everything between 1000-1500 rpm should be all right for your lab.
Max. permissible temperature and humidity
If you work in a humid lab or you intend to blend hot material, have a look at the max. allowed working temperature and humidity of the instrument.
Mounting surface dimensions
The surface dimension obviously defines the size of the beakers you can use with each magnetic stirrer. Your beaker could have a max. diameter as the plate.
A magnetic stirrer obviously needs a magnet to operate. Magnets are available in all possible sizes and forms, from simple rods to starts, ellipsoids, discs etc. I would recommend that you start with a simple rod at the beginning.
The size of the stirring rod should be suitable for your beaker. Usually 0,5-1,0 cm smaller than the diameter of the beaker. If you’re working with different beaker sizes (which you certainly do), you’ll need different magnetic rods.
We have covered all important features you need to know before purchasing a magnetic stirrer.
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