The Function of Magnetic Stirrers in Laboratories: Types and Uses

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Once you’ve learned the purpose of magnetic stirrers in labs, you’ll want to get your hands on one soon!

There are so many tasks involved in chemical and biological laboratories. Agitation and stirring processes are no exceptions.

Lab technicians need to use the best equipment for the job to ensure the results are consistent. Among the ideal tools for agitation are magnetic stirrers.

Here, we will discover what magnetic stirrers are to help you better understand them.

What Are Magnetic Stirrers?

A magnetic stirrer is often used with a hot plate. It agitates the liquid to speed up reactions or improve mixtures.

The rotating magnet creates a ‘rotating magnetic field’, which provides the stirring action. Thus, with the movement, it mixes the samples thoroughly.

Modern models let users control the magnetic field’s speed. This feature allows you to customise the speed as per the specific sample’s needs.

Depending on the application, you can configure it with hot plates to heat your samples simultaneously. The addition of heat plates allows you to mix various samples for different applications.

Essentially, this device is used to cause a stir bar immersed in a liquid to spin very quickly, agitating or mixing the liquid.

Note: You should use glass or non-metal beakers for the samples. This is to prevent interference with the magnetic field.

How Does it Work?

A stir bar magnet is placed inside a container, immersed in the fluid. Then a separate magnet is set underneath the vessel to attract the stir bar magnet.

The lower magnet is attached to a motor that spins it. If the magnets are close enough, the stir bar magnet spins inside the case.

To put it simply, a magnetic stirrer uses the principle of magnetic field and vortex. Put the sample (in the vessel) on the base, and it will generate a rotating magnetic field.

This will drive stirrers, forming a vortex in the vessel – in this way, stirring the liquid.

Function and Uses of Magnetic Stirrers

Magnetic stirrers are ideal for mixing components, either solids or liquids, to get a homogeneous liquid mixture. Some of the common samples include bacterial growth media and buffer solutions.

But as mentioned, their main function is to agitate the liquid. Either for speeding up reactions or improving mixtures.

The stirring function:

• To speed up reaction or evaporation, opt for a shorter reaction time. The same goes for mixing the reaction material thoroughly and balancing temperature distribution.
• When heating material in an airtight vessel, magnetic stirring can prevent bumping.

The heating function:

The temperature range of the heating device is generally between room temperature to 100℃. Take note that some standard types of magnetic stirrers only have a stirring function.

Different Types of Magnetic Stirrers

There are several types of magnetic stirrers. It all depends on your selection of size, application and configuration.

1. Magnetic mini stirrer

A compact sized stirrer that allows the user to regulate the speed with great precision. Designed to resist harmful chemicals present in a lab environment.

Most mini magnetic stirrers consist of a speed regulator. This feature ensures the device never exceeds the maximum speed.

Excellent examples of this type of stirrer are the magnetic stirrers from AME and Ohaus!

 

AME Magnetic Stirrer HMS-901

No longer available

Product code: LQ2115

The AME Magnetic Stirrer uses two high strength magnets to induce a current into a water vessel placed on top. Features include:

• ND Servo Motor stirrer drive
• 0–1250 RPM speed range
• Stepless turntable speed control
• Easy to clean and control

Magnetic Stirrer Ohaus Mini

No longer available

Product code: LQ2072

The OHAUS Mini Magnetic Stirrer is a rugged, compact unit that can stir up to 1000 ml of liquid. It is ideal for educational purposes and also other lab environments that require consistent stirring.

It features a 102 x 102 mm, easy-to-clean ceramic top plate and Valox polymer housing.

2. Magnetic stirrer with timer

This type of stirrer can automatically shut off the motor after a set amount of time. It uses an inbuilt timer to shut off the stirrer when the pre-selected period of time has been over.

The speed is also automatically reduced while the load is removed. Have a look at this magnetic stirrer with a timer from Ohaus!

Ohaus Magnetic Stirrer Mini Auto Start/Stop

No longer available

Product code: LQ2072AS

The OHAUS mini magnetic stirrer is a rugged, compact unit that can stir up to 1000 ml of liquid. It has an auto start/stop function when the beaker/flask is added or removed.

It features a 102 x 102 mm, easy-to-clean ceramic top plate and Valox polymer housing. Ideal for educational purposes and also other lab environments that require constant stirring.

3. Heavy-duty magnetic stirrers

This type of stirrer is true to its name. It features a greater chemical resistance and is highly durable. Also, it has a high level of mixing capacity.

The internal electronic control device it comes with can regulate the speed automatically. Heavy-duty magnetic stirrers sure are perfect for use in a lab or production environment.

Check out our offer below!

 

IEC Magnetic Stirrer & Hotplate with Thermostat Control and PTFE Top (Teflon)

Product code: LQ2093-001

This Teflon coated IEC magnetic stirrer has a maximum temperature setting of 320°C. The plate is covered with a char-grey PTFE (Teflon) coating, making it more hard-wearing and robust against chemicals.

This makes the unit suited for lower temperature work in a lab or melting solids at specific temperatures. The front panel features a mains switch and a heat control knob. Also a knob to control the speed of the magnetic stirrer.

4. Battery-powered magnetic stirrers

The battery-powered magnetic stirrer comes in handy where there is no electric outlet. Their main application is in incubators.

This unit consists of rubber feet and speed control knobs. Alkaline batteries can be used, though rechargeable ones should work just fine.

5. Air operated turbine magnetic stirrer

An air operated turbine magnetic stirrer is perfect for mixing liquid up to 1 litre of solution. It uses a low-pressure air supply for power.

Its major advantage is it eradicates the sparking hazard from electrical sources.

The Bottom Line

It turns out that the wrong agitation process can lead to inaccurate results. If you use the wrong equipment, you won’t get the level of performance or consistency you need.

Hence why it is crucial to understand the agitation options as per applications. This is where magnetic stirrer hot plates come into the picture.

The primary use of a magnetic stirrer is to conduct biological and chemical experiments by mixing two components. It is equally suitable for solids or liquid samples to get a consistent liquid mixture.

And now that you know how magnetic stirrers work and their function, it is time for you to invest in one. Our selection of hotplates and stirrers will make your money worthwhile!