Laboratory Stirrer Selection and Maintenance Guide
Laboratory stirrers provide the mixing action essential for sample preparation, chemical synthesis, and dissolution testing. Proper selection ensures efficient mixing for each application.
I. Selection Criteria
- Viscosity: Magnetic stirrers are suitable for low to medium viscosity. Overhead stirrers handle medium to high viscosity materials.
- Volume: Match the stirrer capacity to the sample volume. Overhead stirrers can handle larger volumes than magnetic stirrers.
- Temperature: For heated applications, select a hotplate stirrer with adequate temperature range and control accuracy.
- Chemical Compatibility: Ensure stir bar, impeller, and vessel materials are compatible with the chemicals being mixed.
II. Operation
- Place the vessel securely on the stirrer or clamp it in place for overhead stirrers
- For magnetic stirrers, start at low speed to ensure the stir bar is captured before increasing
- For overhead stirrers, center the impeller in the vessel and adjust the height for optimal mixing without splashing
- Monitor the mixing and adjust speed as needed
III. Maintenance
- Clean stirrer surfaces after each use to prevent chemical residue buildup
- For overhead stirrers, inspect the chuck for wear and lubricate per manufacturer instructions
- Check magnetic stirrer heating elements for even heating across the plate surface
- Replace damaged power cords immediately
- Calibrate speed control and temperature display annually
