Mixers & Stirrers

Magnetic stirrers work well for low viscosity liquids up to a few litres, but the coupling between magnet and stir bar slips once the fluid thickens or the volume grows. Viscous suspensions, gels and large vessels need an overhead stirrer, which drives an impeller directly with far more torque. If your stir bar stops tracking the magnet or throws out of the vessel, that is the sign to move to overhead drive.

Check that the plate heats evenly and reaches setpoint, since worn heating elements and failed temperature feedback are the usual faults. Confirm the stirring motor runs smoothly across its speed range and couples reliably to a stir bar. Examine the plate surface for chemical damage and cracks, and ask whether a temperature probe is included, because probes are useful and not always supplied with used units.

Within limits set by its rated capacity and magnet strength, yes, since most units cover from small beakers up to their stated maximum, often one to twenty litres depending on model. Beyond the rated volume the stir bar loses coupling and mixing becomes ineffective. Choose a unit whose maximum comfortably exceeds your largest routine volume, and use an appropriately sized stir bar for the vessel.

Rotor stator homogenisers are specified by the sample volume and the type of material, since tough tissue needs different generator geometry and power than soft samples or emulsions. Confirm the generator probes included cover your volume range, as probes are consumable and application specific. Ask the seller what materials the unit processed, because that indicates both suitability and the wear the generators have seen.

You deal with the seller directly through Machinery Masters, asking about condition, included accessories and testing, then agreeing price and delivery between you with no middleman involved. For inexpensive bench units this is usually quick and straightforward. If you are buying several units or higher value homogenisers, finance on qualifying listings is available to spread the cost.