CZGY CJJ-931 Dual-Position Magnetic Hotplate Stirrer

Overview

The CZGY CJJ-931 Dual-Position Magnetic Hotplate Stirrer is an engineered solution for parallel sample preparation in quality control, analytical chemistry, environmental testing, and academic research laboratories. Designed on the principle of magnetic coupling—where a rotating permanent magnet beneath a thermally conductive ceramic or aluminum plate induces rotation of a PTFE-coated stir bar immersed in liquid—the instrument delivers precise, contactless agitation without mechanical shaft penetration. Integrated resistive heating elements provide uniform thermal distribution across two independent work zones, enabling simultaneous temperature-controlled mixing of up to two 1 L vessels. Its robust architecture supports reproducible kinetic studies, dissolution testing, reagent homogenization, and buffer equilibration under defined thermal and rotational conditions—critical for method development aligned with ISO/IEC 17025 and GLP-compliant workflows.

Key Features

• Dual independent stations with individual on/off switches for stirring and heating—enabling flexible operation (e.g., one station heating only, the other stirring only, or both active simultaneously)
• Smooth, stepless speed control from 0 to 1600 rpm via analog rotary dial; gradual acceleration prevents stir bar “jumping” and ensures stable vortex formation in low- to medium-viscosity aqueous and organic solutions
• Adjustable digital or analog temperature setpoint (ambient to 100 °C) with proportional control logic; surface temperature uniformity ≤ ±5 °C across each 12 cm diameter plate at steady state
• Compact footprint (approx. 280 × 160 × 120 mm) optimized for benchtop use in fume hoods or laminar flow cabinets
• Ceramic-coated aluminum hotplate surface—chemically resistant, easy to clean, and non-magnetic to prevent interference with stir bar dynamics
• Thermal cut-off protection and grounded chassis design compliant with IEC 61010-1 safety standards for laboratory electrical equipment

Sample Compatibility & Compliance

The CJJ-931 accommodates standard borosilicate glass beakers (up to 1000 mL), Erlenmeyer flasks, and cylindrical reaction vessels with flat, non-tapered bases. It is suitable for aqueous buffers, saline solutions, ethanol/water mixtures, and dilute acid/base preparations. Not recommended for highly viscous media (>500 mPa·s), volatile solvents without condenser setup, or corrosive hydrofluoric acid systems. The device meets CE marking requirements for electromagnetic compatibility (EMC Directive 2014/30/EU) and low-voltage safety (LVD Directive 2014/35/EU). While not certified to FDA 21 CFR Part 11, its manual operation mode supports audit-ready documentation when used within validated SOPs for USP dissolution apparatus qualification or ASTM D2624 viscosity sample conditioning.

Software & Data Management

As a manually operated analog instrument, the CJJ-931 does not incorporate embedded firmware, touchscreen interface, or data logging capability. All operational parameters—speed and temperature—are set and monitored locally via front-panel dials and analog indicators. This architecture eliminates cybersecurity vulnerabilities and simplifies qualification for regulated environments where deterministic, non-networked hardware is preferred. Users are advised to record setpoints and runtime manually in lab notebooks or LIMS-integrated electronic records. Optional external PT100 probes (not included) may be used with third-party temperature loggers for retrospective thermal profiling during long-duration experiments.

Applications

• Simultaneous pH adjustment and buffer equilibration across duplicate samples prior to HPLC or titration analysis
• Preparation of calibration standards in environmental labs (e.g., heavy metal stock solutions per EPA Method 200.7)
• Accelerated stability testing of pharmaceutical suspensions under controlled thermal agitation
• Soil extractant homogenization (e.g., Mehlich-3 or Olsen extraction protocols) in agricultural testing labs
• Pre-incubation of enzyme-substrate mixtures in biochemistry teaching labs
• Supporting ASTM D7928 grain-size analysis via hydrometer sedimentation with continuous mixing

FAQ

Can the CJJ-931 operate two different temperatures simultaneously?

No. Both stations share a common thermal control circuit and therefore maintain identical setpoint temperatures. Independent temperature control requires multi-zone instruments such as the CZGY CJJ-934 series.
Is it safe to use the stirrer with flammable solvents?

Only under strict engineering controls: solvent vapors must be removed via fume hood ventilation; surface temperature must remain below the autoignition point of the solvent (e.g., <130 °C for ethanol); and no open flames or spark sources should be present.
What stir bar size is recommended for optimal performance at 1600 rpm?

A 30–40 mm elliptical PTFE-coated stir bar (e.g., 35 × 8 mm) provides stable rotation in 1 L beakers at maximum speed without orbital deviation.
Does the unit include a calibration certificate?

No. Calibration of speed and temperature must be performed in-house using traceable tachometers and NIST-traceable RTD probes per laboratory quality management system requirements.
Can the hotplate surface be replaced if damaged?

Yes. CZGY supplies replacement ceramic-aluminum top plates (part number CJJ-PLATE-2P) as field-service components compatible with all CJJ-931 units manufactured after 2020.