Magnetic stirrers are indispensable in any chemistry or biology laboratory. They provide efficient, consistent mixing without the need for mechanical shafts or paddles. Selecting the right magnetic stirrer depends on volume, viscosity, speed range, and temperature control requirements.
Stirrer Types
| Type | Speed Range (RPM) | Max Volume | Best For |
|---|---|---|---|
| Basic Stirrer | 100-1500 | 2 L | Buffer mixing, routine stirring |
| Hotplate Stirrer | 100-1500 | 5 L | Heating + stirring, synthesis |
| Multi-position Stirrer | 100-1200 | 1 L per position | Parallel reactions, high throughput |
| Overhead Stirrer | 30-2000 | 50 L+ | Viscous solutions, large volume |
Stir Bar Selection Guide
Matching your stir bar to the vessel size and volume is crucial:
- 100-500 mL beaker — stir bar length 20-30 mm
- 500 mL - 1 L beaker — stir bar length 40-50 mm
- 1 L - 2 L beaker — stir bar length 60-80 mm
- Oval/pivot bars — for round-bottom flasks
- Cross bars — for high-viscosity solutions
Speed and Viscosity
For low-viscosity solutions (water, buffers), 300-500 RPM is usually sufficient. As viscosity increases, higher RPM (800-1200+) may be needed. However, excessive speed in low-viscosity fluids can create vortexing and air entrainment, potentially affecting oxygen-sensitive reactions.
Why JWRESEARCH Stirrers?
JWRESEARCH magnetic stirrers are designed with brushless DC motors for quiet, maintenance-free operation. Available through JW RESEARCH SUPPLY Singapore, they feature digital speed display, programmable timers, and optional heating functions for versatile lab use.