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Purchasing Guides

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Stirrers & Mixers

What to consider when choosing a stirrer or mixer for your laboratory

Lab Manager
OHAUS Guardian 5000 Hotplate Stirrers, www.ohaus.com.
OHAUS

As you’d expect, stirrers and mixers are used for mixing a variety of samples in the lab, and there are numerous options available depending on what you’re mixing and the volume you’re working with. Some applications are suited to a magnetic stirrer, which relies on a rotating magnetic field to rotate a stir bar within the liquid. Magnetic stirrers are available with heated or non-heated platforms. Overhead stirrers with a drive motor to power the impeller are better suited to more viscous liquids or larger volumes. For a list of stirrer and mixer manufacturers, see our online directory: LabManager.com/stirrer-mixer-manufacturers



8 Questions to Ask When Buying a Stirrer or Mixer:

  1. What sample volumes will you be working with?
  2. What is the intended application? Magnetic stirrers are best suited to applications that require low shear mixing.
  3. How viscous are the samples? Highly viscous samples may create too much resistance for a magnetic stirrer.
  4. What mixing speeds are required? 
  5. Is a heated platform required?
  6. What vessels will you be working with? Overhead stirrers can be used with both flat-bottom vessels and closed reaction systems with round-bottom flasks.
  7. Does the device have a digital display for speed and torque, as well as a timer?
  8. What type of motor is used? Are the torque and speed specifications suited to your applications?

Choosing Accessories

If you’re using a magnetic stirrer for analytical chemistry applications, it’s important to note that the Teflon coating of stir bars can acquire pocks and abrasions over time, attracting and incorporating trace metals including gold, palladium, nickel, and iron, which may impact your reactions. In this case, it may be best to stir solutions with stainless steel impellers driven by motors. LabManager.com/PRG-2022-stirrers-mixers

Purchasing Tip

When looking for a stirrer, it’s important to consider the instrument’s interface. While it might seem like a small factor, if the interface is not easy to use, it can make complicated chemistry even more frustrating.