OHAUS Guardian 3000 7×7 Ceramic-Plate Heating Magnetic Stirrer

Overview

The OHAUS Guardian 3000 7×7 Ceramic-Plate Heating Magnetic Stirrer is an engineered solution for laboratories requiring reliable, high-duty-cycle thermal mixing under precise and safe operational conditions. Built upon a robust electromagnetic coupling principle, the device utilizes a rotating magnetic field generated beneath a chemically inert ceramic surface to drive PTFE- or glass-coated stir bars within vessels—enabling contactless agitation without mechanical shaft penetration. Its integrated resistive heating element delivers uniform thermal distribution across the 7×7 inch (178×178 mm) ceramic plate, supporting applications ranging from solvent-based synthesis to high-viscosity polymer dissolution and temperature-sensitive biochemical assays. Designed for continuous operation—including extended 720-hour duty cycles with aqueous or silicone oil media—the system incorporates dual-stage thermal regulation to minimize overshoot during ramp-up, ensuring stability critical for reaction kinetics studies, calibration protocols, and GLP-compliant sample preparation.

Key Features

• High-power ceramic heating plate rated for sustained operation up to 500°C, with ±1°C temperature accuracy across the full control range (ambient +5°C to 500°C)
• Wide-speed magnetic drive delivering consistent torque from 80 to 1600 rpm, optimized for viscosities up to 10,000 mPa·s at full load
• SafetyHeat™ dual-redundant thermal monitoring system: independent hardware-based overtemperature cutoff and software-monitored thermal feedback loop
• Post-shutdown residual heat indicator: LED warning remains active until plate surface cools below 40°C, preventing accidental contact burns
• Corrosion-resistant stainless steel chassis with passive convection cooling architecture; IP20-rated enclosure suitable for standard laboratory environments
• Intuitive rotary encoder interface with backlit LCD display showing real-time speed, setpoint temperature, elapsed time, and status icons

Sample Compatibility & Compliance

The Guardian 3000 accommodates round-bottom flasks, beakers, and jacketed reactors from 50 mL to 15 L volume capacity, provided appropriate stir bar geometry and vessel bottom flatness are maintained. The smooth, non-porous ceramic surface resists etching from acids, bases, and organic solvents—validated per ISO 15190:2020 Annex A for lab equipment surface durability. Temperature control algorithms comply with ASTM E2912–21 guidelines for thermal stability in heated stirrers used in method validation. While not intrinsically rated for hazardous area use, the unit meets IEC 61010-1:2010 safety requirements for electrical laboratory equipment and supports audit-ready documentation for FDA 21 CFR Part 11–aligned workflows when paired with optional external data loggers.

Software & Data Management

The Guardian 3000 operates as a standalone instrument with embedded firmware supporting programmable ramp-hold profiles (up to 3 segments), timer-based shutdown, and parameter lockout for SOP enforcement. Optional RS-232 or USB-to-serial connectivity enables integration with third-party laboratory information management systems (LIMS) or custom Python/Python-based automation scripts via ASCII command protocol. All parameter changes—including speed adjustments and temperature setpoints—are timestamped and stored in non-volatile memory for traceability. When used with certified temperature probes (e.g., Pt100 Class B), the system supports calibration certificate generation aligned with ISO/IEC 17025:2017 metrological requirements.

Applications

• Controlled heating and homogenization of reagent solutions prior to HPLC or ICP-MS analysis
• Long-duration enzymatic digestions requiring stable 37°C incubation with gentle agitation
• Polymer dissolution and viscosity benchmarking in quality control labs (ASTM D2760, ISO 3219)
• Preparation of calibration standards for atomic absorption spectroscopy under thermally stabilized conditions
• Supporting ASTM D86 distillation setups where bath temperature must remain constant within ±0.5°C
• Cell culture media warming and pH buffer equilibration in biosafety cabinets

FAQ

Is the ceramic plate resistant to hydrofluoric acid exposure?
No—while the alumina-based ceramic surface withstands common mineral acids (HCl, HNO₃, H₂SO₄) and organic solvents, it is not HF-resistant. Use glass or PTFE-coated plates for HF-containing systems.
Can the unit maintain temperature stability during rapid ambient fluctuations?
Yes—the adaptive PID algorithm continuously adjusts power output based on real-time thermal load feedback, achieving ±1.5°C stability even with 5°C/h ambient drift.
Does the device support external temperature probe input by default?
The e-G31HS07C model includes a dedicated Pt100 input port; probe compatibility requires ordering the OHAUS-certified STP-100 sensor separately.
What maintenance intervals are recommended for long-term reliability?
Annual verification of thermal accuracy (per ASTM E74) and stir motor torque calibration is advised; no routine lubrication is required due to brushless DC motor design.
Is firmware upgrade capability available?
Yes—field-upgradable via OHAUS-provided utility software and USB connection; version history and release notes are published on the official OHAUS support portal.