X85-2S Digital Display Constant-Temperature Magnetic Stirrer

Overview

The X85-2S Digital Display Constant-Temperature Magnetic Stirrer is an engineered upgrade of the legacy 85-2 series—originally standardized in the mid-1980s as one of China’s earliest commercially deployed magnetic stirrers featuring brushless DC motor drive. Designed for reliability and functional continuity in routine laboratory workflows, the X85-2S retains the core mechanical advantages of its predecessor—including high-torque output (20 mN·m), wide-speed adjustability, and robust thermal control—while introducing critical modern enhancements: real-time digital speed readout, improved thermal response, and enhanced safety architecture. It operates on the principle of magnetic coupling: a rotating permanent magnet beneath the ceramic-coated aluminum heating plate induces synchronous rotation of a PTFE- or glass-coated magnetic stir bar immersed in the sample vessel. Simultaneous heating and stirring enable efficient thermal homogenization across volumes up to 5 L—making it suitable for dissolution testing, reagent preparation, buffer equilibration, and pre-analytical sample conditioning in chemistry, pharmaceutical, and life science laboratories.

Key Features

• Brushless DC motor delivering consistent torque (20 mN·m) across full speed range (100–1500 rpm), with optional customization to 2000 rpm for high-viscosity applications
• Digital LED speed display providing real-time rotational feedback—eliminating reliance on analog dials and improving protocol reproducibility
• Aluminum die-cast housing with splash-resistant design to prevent ingress of spilled liquids into internal electronics
• 145 mm diameter anodized aluminum heating plate rated at 600 W, enabling rapid thermal ramping from ambient to 300 °C with uniform surface temperature distribution
• Dual-mode temperature control: direct heating plate setpoint regulation (±2 °C typical stability) or external feedback via user-supplied contact thermometer (e.g., mercury or digital probe with SPDT switch output)
• Integrated over-temperature protection cutoff at 330 °C to prevent thermal runaway and ensure compliance with IEC 61010-1 safety requirements for laboratory equipment
• Compact footprint (245 × 150 × 125 mm) optimized for benchtop integration in shared lab environments and teaching laboratories

Sample Compatibility & Compliance

The X85-2S accommodates standard borosilicate glass vessels—including beakers (up to 5000 mL), Erlenmeyer flasks, and jacketed reactors—provided appropriate stir bar geometry and size are selected for viscosity and vessel depth. Its non-inductive heating plate eliminates electromagnetic interference with nearby analytical instrumentation (e.g., balances, pH meters). While not certified to ISO/IEC 17025 or GLP-specific validation protocols out-of-the-box, the device supports traceable operation when used with calibrated stir bars, NIST-traceable thermometers, and documented SOPs. It meets general electrical safety standards per GB 4793.1–2007 (equivalent to IEC 61010-1) and is compatible with laboratory quality systems requiring documented parameter control—particularly where heating/stirring steps are part of ASTM D129, USP , or ISO 17025 method validation workflows.

Software & Data Management

The X85-2S is a stand-alone analog-digital hybrid instrument with no embedded microprocessor or data logging capability. All operational parameters—speed and heating plate setpoint—are adjusted manually via dual precision potentiometers with tactile detents and visual LED indicators. The digital speed display provides immediate operator feedback but does not interface with external computers, SCADA systems, or LIMS platforms. For regulated environments requiring audit trails, users may integrate the unit into validated processes by pairing it with external data loggers (e.g., HOBO UX100 series) connected to the heating plate thermocouple output (if retrofitted) or by recording setpoints and observed outcomes in electronic lab notebooks (ELNs) compliant with 21 CFR Part 11 when configured with appropriate signature controls.

Applications

• Preparation of homogeneous aqueous and organic solutions in QC/QA labs—especially for titrant standardization, buffer dilution, and mobile phase mixing prior to HPLC analysis
• Controlled-temperature dissolution testing of solid dosage forms under USP apparatus II conditions (with appropriate vessel mounting)
• Cell culture media warming and component dispersion without shear-induced protein denaturation
• Chemical synthesis support: reflux pre-heating, catalyst suspension, and reaction mixture homogenization in undergraduate and graduate teaching labs
• Calibration support for viscometers and density meters requiring temperature-stabilized reference fluids

FAQ

Does the X85-2S support external temperature feedback control?
Yes—via rear-panel terminals accepting SPDT contact signals from user-supplied capillary or digital contact thermometers (e.g., mercury-filled or bimetallic switch types). This enables closed-loop liquid-phase temperature regulation independent of heating plate setpoint.
What is the maximum recommended viscosity for stable stirring at 1500 rpm?
For optimal performance, the unit is intended for low-to-medium viscosity liquids (< 500 mPa·s at 25 °C); higher viscosities require lower speeds and larger stir bars to maintain coupling efficiency and prevent decoupling.
Is the heating plate surface chemically resistant?
The anodized aluminum surface offers moderate resistance to mild acids, bases, and solvents; however, prolonged exposure to strong oxidizers (e.g., concentrated HNO₃) or halogenated solvents may degrade the oxide layer—use PTFE-coated stir bars and avoid direct contact with corrosive spills.
Can the X85-2S be used in inert atmosphere gloveboxes?
Yes—provided adequate ventilation is maintained around the unit’s rear vents and power supply is routed through a feedthrough; note that internal electronics are not intrinsically safe or explosion-proof.
Are calibration certificates available for factory-set speed or temperature accuracy?
No—calibration is user-responsibility per ISO/IEC 17025; however, speed accuracy is typically ±2% of full scale, and heating plate temperature uniformity across the central 100 mm zone is ≤ ±5 °C at 100 °C steady state.