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Laboratory Overhead Stirrer

It is a laboratory Instruments utilized for recirculating, suspending, homogenizing, and mixing high-viscosity or large volumes substances, which mostly can’t be handled by a magnetic stirrer.

Overhead stirrers are utilized in applications like pharmaceutical synthesis, chemical synthesis, chemical, and physical analysis as well as in the petrochemical industry.


At Kumar Instruments, an overhead stirrer’s tools are connected to the drive motor by a chunk, so it’s less likely to experience difficulty with a more viscous sample. The overhead stirrer does offer a variety of stirring tools, such as blades, impellers, and paddles.

However, if you decide on between purchasing one or the other for the lab, there are several things you require to consider:

1.           Volume of samples
2.           Viscosity of samples
3.           Heat required
4.           Type of mixing required

1. Volume of Samples

If you’re processing big volumes, you want to make certain your Scientific Instruments can handle it. Depending on the model, overhead stirrers do handle maximum volumes between 15–100 L. Bigger volume overhead stirrers do exist, but they are considered industrial or process equipment.

Volume and vessel size are significant if you’re going to be scaling up your method. overhead stirrer processes are easy to scale up beyond that.

2. Viscosity of Samples

In common, more energy can be offered with an overhead stirrer, so these tend to work much better for more viscous samples. However, overhead has limitations when it comes to viscous samples.

With overhead, if you have a high-viscosity sample, either at the beginning of or during processing, there is a risk of straining the drive motor, causing it to wear and overheat quickly. Some will detect torque and if it gets too high, the power will be lessened or the unit will shut off entirely. Others have red warning lights to signify they’re overloaded. Most have a small internal fan which supports to ignore overheating of the motor.

3. Heat Required

If heat is needed during processing, you have some options. You could utilize an overhead stirrer with a heat source, such as oil or water bath or a hotplate.

In this case, aside from considering the viscosity and volume, you also need to think about how your sample will be heated. An oil or water bath is often preferred for heating bigger samples, as heat is applied to a greater surface zone of the vessel, permitting for faster, more even heating. However, a water bath is pretty likely to introduce contamination to samples, so for certain uses, might require to be ignored.

4. Type of Mixing Required

For extremely viscous materials, an overhead mixer with a paddle could be a great option, In general, overhead is more flexible due to the huge number of impeller options available, plus the fact that you can change the position of the impeller head. While there are different kinds of stir bars available, they require to sit at the bottom of the vessel to regulate coupling.

Overhead stirrers are often more advantageous for applications like wetting thickening and mixing emulsions agents. It also gives you more control over matters like aeration, presence or size, vortex, and shear.

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