SiLe 85-2 & 81-2 Precision Heated Magnetic Stirrers

Overview

The SiLe 85-2 and 81-2 are benchtop heated magnetic stirrers engineered for precision temperature-controlled mixing in academic, industrial, and quality control laboratories. These instruments operate on the principle of rotating magnetic fields generated by a permanent magnet array beneath a thermally conductive ceramic or black-coated stainless-steel heating plate. A magnetic stir bar immersed in the sample couples with this field, enabling contactless agitation without mechanical shaft penetration—thereby eliminating contamination risk and seal wear. Both models integrate independent proportional-integral (PI) temperature control and pulse-width modulated (PWM) motor drive circuits, ensuring stable thermal output and consistent rotational speed across variable load conditions. Designed for continuous-duty operation under GLP-compliant workflows, they support reproducible dissolution testing, buffer preparation, reagent synthesis, and pre-analytical sample homogenization where simultaneous heating and mixing are required.

Key Features

• Two-tier model selection: 85-2 optimized for high-volume applications up to 10 L (water equivalent); 81-2 configured for compact bench use with 3 L capacity and lower power consumption
• Wide-speed digital control: 100–2000 rpm (85-2) and 100–1300 rpm (81-2), adjustable via rotary encoder with real-time RPM feedback
• Precise thermostatic regulation: ambient-to-100 °C range with ±1 °C accuracy, validated using calibrated Pt100 sensor feedback
• Robust heating architecture: 340 W (85-2) / 300 W (81-2) resistive heating element embedded beneath a Ø140 mm corrosion-resistant heater plate
• High-torque DC motors: 20 mN·m (85-2) and 15 mN·m (81-2) torque output ensures reliable stirring even with viscous or dense suspensions
• Compact footprint (250×145×130 mm) and lightweight design (4 kg) facilitate integration into fume hoods, incubators, or modular lab benches
• Standard accessories include dual-length support rods and a set of PTFE-coated magnetic stir bars; external temperature monitoring via optional mercury contact thermometer (user-supplied)

Sample Compatibility & Compliance

The SiLe 85-2 and 81-2 accommodate standard laboratory glassware—including beakers, Erlenmeyer flasks, and jacketed reactors—up to 100 mm base diameter. Their non-reactive heater surface is compatible with aqueous, organic, and mildly acidic solutions. While not certified to IEC 61000-4 electromagnetic immunity standards out-of-box, both units meet basic CE marking requirements for laboratory electrical safety (EN 61010-1). For regulated environments, users may configure these stirrers within validated SOPs aligned with ISO/IEC 17025 calibration practices. Temperature and speed settings are manually recorded; when paired with external data loggers or validated temperature probes, the systems support traceability per FDA 21 CFR Part 11 Annex 11 principles for electronic records in pharmaceutical QC labs.

Software & Data Management

These analog-digital hybrid stirrers do not incorporate embedded firmware, network connectivity, or proprietary software. All operational parameters—speed and temperature—are set locally via front-panel controls and retained only during active power supply. No audit trail, password protection, or electronic signature capability is provided. For laboratories requiring electronic data capture, integration with third-party environmental monitoring systems (e.g., Omega iServer, Testo Saveris) is achievable using analog 0–10 V or 4–20 mA output modules (sold separately). Calibration certificates for temperature and speed verification can be issued upon request, supporting routine maintenance per ASTM E2457 (Standard Practice for Calibration of Laboratory Equipment).

Applications

• Preparation of homogeneous buffer solutions and culture media in microbiology and molecular biology labs
• Dissolution testing of solid dosage forms under USP conditions (when used with appropriate vessels and temperature validation)
• Controlled heating and mixing during chemical synthesis, catalyst activation, or polymerization initiation
• Stabilization of reaction mixtures prior to HPLC, GC, or spectrophotometric analysis
• Calibration of temperature sensors and viscosity standards in metrology laboratories
• Teaching demonstrations of heat transfer kinetics and fluid dynamics in undergraduate chemistry curricula

FAQ

Do the SiLe 85-2 and 81-2 support external temperature probe input for closed-loop feedback?
No—both models rely on internal plate-mounted Pt100 sensors. External probe integration requires aftermarket PID controllers with analog input capability.
Are PTFE-coated stir bars included with each unit?
Yes—a complete set of standard PTFE-coated magnetic stir bars is supplied with every unit, along with two support rods (long and short).
Can these stirrers operate continuously for 24/7 applications?
Yes—designed for continuous-duty operation under rated load; recommended ambient temperature range is 15–30 °C with adequate ventilation.
Is the heater plate surface chemically resistant to common solvents?
The black-coated stainless-steel surface (81-2) and ceramic-coated plate (85-2) resist water, alcohols, and dilute acids; avoid prolonged exposure to halogenated or strong oxidizing agents.
What is the maximum viscosity these stirrers can handle at full speed?
At 2000 rpm (85-2), optimal performance is maintained up to ~500 mPa·s (e.g., 1% CMC solution); higher viscosities require reduced speed and larger stir bars for torque efficiency.