OHAUS Guardian 7000 Heated Magnetic Stirrer

Overview

The OHAUS Guardian 7000 Heated Magnetic Stirrer is an engineered solution for laboratories requiring precise, reproducible heating and mixing under controlled conditions. Based on Couette flow principles, it employs a permanent rare-earth magnet coupled with a brushless DC motor to deliver consistent torque across its full speed range—enabling stable agitation of low- to high-viscosity liquids without slippage. The integrated PTC (Positive Temperature Coefficient) heating system, combined with dual independent thermal sensors, ensures rapid, uniform heat distribution across the ceramic or aluminum plate surface while maintaining tight temperature stability (±1 °C typical at setpoint). Designed for continuous operation in demanding QC, R&D, and teaching environments, the unit complies with IEC/EN 61010-1 and related safety standards for laboratory electrical equipment, making it suitable for GLP-compliant workflows where traceability and operational integrity are critical.

Key Features

• SmartHeat™ Dual-Sensor Thermal Management: Two redundant temperature sensors continuously monitor plate surface and internal housing temperatures; automatic heater shutdown occurs if either exceeds user-defined or safety-limited thresholds.
• SmartPresence™ & SmartLink™ User Monitoring: Infrared-based presence detection initiates a configurable timeout sequence—if no user interaction is detected beyond the preset interval, heating is disabled while stirring may continue (configurable), mitigating unattended-operation risks.
• SmartRate™ Ramp Control: Programmable heating and speed ramp profiles allow gradual temperature or RPM transitions—critical for preventing bumping in volatile solvent systems or thermal shock in sensitive biological suspensions.
• Robust Mechanical Architecture: Sealed, maintenance-free motor with optimized magnetic coupling delivers sustained torque up to 1600 rpm—even in viscous media (e.g., polymer solutions, glycerol-water mixtures) and at elevated temperatures.
• IP21-Rated Enclosure with SmartHousing™ Design: Chemically resistant, non-porous housing incorporates sloped front panel and internal drainage channels to prevent liquid ingress; tempered glass control surface resists scratching and thermal stress.
• Programmable Workflow Support: Five multi-step protocols can be stored locally and recalled via USB interface—each supporting independent setpoints for temperature, speed, duration, and ramp rates—ideal for SOP-driven applications.

Sample Compatibility & Compliance

The Guardian 7000 accommodates standard laboratory vessels—including borosilicate glass beakers (up to 20 L), stainless steel containers, and compatible plasticware—provided magnetic stir bars are appropriately sized and coated (e.g., PTFE or glass-coated). Its wide temperature span (ambient +5 °C to 500 °C) supports applications ranging from gentle buffer equilibration to high-temperature synthesis pre-heating. All electrical and electromagnetic safety certifications meet international requirements for Class A equipment in basic laboratory environments (IEC/EN 61326-1). Full compliance with IEC/EN 61010-2-010 (safety for heating equipment) and IEC/EN 61010-2-051 (safety for stirring equipment) ensures suitability for ISO/IEC 17025-accredited labs. The device supports audit-ready operation through timestamped protocol execution logs when used with optional OHAUS data management software.

Software & Data Management

While standalone operation requires no software, the built-in USB port enables firmware updates and protocol transfer using OHAUS’ free Guardian Configuration Utility (Windows/macOS compatible). This utility allows users to define, validate, and export multi-stage programs—including conditional logic for temperature-speed interdependence—and generate PDF-based setup reports for documentation purposes. When integrated into networked lab environments, the device’s deterministic behavior and repeatable parameter recall support 21 CFR Part 11–aligned workflows when paired with validated third-party electronic lab notebook (ELN) systems that capture USB-initiated event logs.

Applications

• Preparation of homogeneous reagent solutions and calibration standards in analytical chemistry labs
• Heating and mixing during titration, dissolution testing (USP ), and extraction procedures
• Controlled thermal activation of catalysts or enzymatic reactions in life science research
• Viscosity-reduction pretreatment of samples prior to filtration or centrifugation
• Material synthesis steps requiring inert-atmosphere-compatible heating (when used with appropriate vessel lids)
• Teaching labs emphasizing safe, hands-on demonstration of thermal kinetics and mass transfer principles

FAQ

Does the Guardian 7000 support external temperature probes?
Yes—optional RTD or thermistor probes can be connected via the dedicated analog input port for accurate sample-core temperature feedback, enabling closed-loop control independent of plate surface readings.
What is the maximum recommended viscosity for reliable stirring at 500 °C?
At elevated temperatures, effective upper viscosity limit depends on vessel geometry and stir bar size; for standard 100 mm beakers, viscosities up to ~5000 mPa·s remain controllable at 800–1200 rpm using a 40 mm elliptical stir bar.
Can protocols be password-protected?
Local storage does not include user-level authentication; however, protocol files exported via USB may be encrypted externally, and execution logs within ELN-integrated deployments support role-based access controls.
Is the heating plate interchangeable between ceramic and aluminum variants?
No—the plate type is fixed per model configuration (e-G71HS07C specifies ceramic); aluminum-plate variants are available under separate model numbers and require factory service for replacement.
How frequently should the SmartPresence™ sensor be calibrated?
The infrared sensor is factory-calibrated and requires no routine recalibration; periodic verification using the built-in self-test mode (accessible via service menu) is recommended annually or after physical impact to the front panel.