MKN HJ-A6 Magnetic Stirring Constant-Temperature Water Bath

Overview

The MKN HJ-A6 Magnetic Stirring Constant-Temperature Water Bath is an integrated laboratory instrument engineered for precise thermal control and simultaneous agitation of multiple samples in aqueous or low-viscosity media. It operates on the principle of convective heat transfer via a far-infrared heating system coupled with forced convection induced by six independently controlled magnetic stirrers. Unlike conventional water baths that rely solely on passive thermal equilibrium, the HJ-A6 actively enhances temperature homogeneity through synchronized stirring—reducing thermal stratification and minimizing localized hot/cold zones. This dual-function architecture ensures rapid thermal equilibration (typical heat-up time to 60 °C: <12 min) and sustained stability within ±0.5 °C across the entire bath volume. The unit is purpose-built for applications requiring both thermal consistency and mechanical mixing—particularly where sample integrity depends on uniform energy distribution and absence of sedimentation or concentration gradients.

Key Features

• Six independent magnetic stirring stations—each with adjustable speed control (0–1200 rpm typical range), enabling parallel processing of heterogeneous sample sets without cross-contamination.
• High-precision temperature regulation using dual-integration A/D conversion circuitry and high-stability operational amplifiers, delivering consistent setpoint tracking even during dynamic load changes (e.g., cold sample insertion).
• Far-infrared heating module mounted beneath the stainless-steel bath chamber ensures efficient, contactless thermal transfer—minimizing thermal stress on the tank structure and extending service life.
• Robust AISI 304-grade stainless-steel construction (equivalent to imported stainless steel per GB/T 20878–2007), resistant to corrosion from repeated exposure to water, saline solutions, and mild organic solvents.
• LED digital interface displaying both set temperature and real-time bath temperature simultaneously—supporting immediate visual verification and reducing operator error during multi-step protocols.
• Optimized chamber geometry (460 × 320 × 120 mm internal dimensions) accommodates standard round-bottom flasks (up to 2 L), test tubes, centrifuge tubes, and custom vessels—while maintaining adequate clearance for stir bar rotation and thermal circulation.

Sample Compatibility & Compliance

The HJ-A6 supports a broad range of sample containers—including borosilicate glass, polypropylene, and PTFE-lined vessels—provided they are compatible with temperatures up to 99.9 °C and non-reactive with magnetic fields. It is routinely deployed in settings governed by GLP (Good Laboratory Practice) and ISO/IEC 17025 requirements, where traceable temperature calibration and documented thermal performance are essential. While not certified to FDA 21 CFR Part 11 out-of-the-box, its stable analog control architecture allows integration into validated workflows when paired with external data loggers compliant with audit-trail and electronic signature standards. The unit meets CE marking criteria for electromagnetic compatibility (EMC Directive 2014/30/EU) and low-voltage safety (LVD Directive 2014/35/EU). No hazardous substances (per RoHS 2011/65/EU) are used in critical components.

Software & Data Management

The HJ-A6 operates as a standalone analog-digital hybrid system with no embedded firmware or network connectivity. Temperature and stirring parameters are configured manually via front-panel controls; all operational data remain local and unrecorded unless interfaced externally. For regulated environments, users may connect third-party calibrated thermocouple probes (e.g., Pt100 Class A) to external data acquisition systems (e.g., LabVIEW, Delta Tau PMAC, or Eurotherm 2408) to generate time-stamped thermal profiles compliant with 21 CFR Part 11 Annex 11 requirements. Optional RS-485 or 0–10 V analog output modules (sold separately) enable integration into centralized lab monitoring platforms for remote status verification and alarm triggering.

Applications

• Controlled evaporation of solvent mixtures in analytical sample preparation (e.g., prior to GC-MS or ICP-MS analysis).
• Temperature-dependent enzymatic reactions requiring simultaneous agitation—such as kinase assays, DNA ligation, or antibody conjugation protocols.
• Standardized dissolution testing of pharmaceutical dosage forms per USP , where vessel agitation and bath temperature must comply with strict tolerances.
• Pre-incubation of microbial cultures in liquid media under defined thermal conditions before inoculation or viability assessment.
• Accelerated aging studies of polymer solutions, colloidal suspensions, or emulsions where thermal history and shear history must be decoupled and reproducibly applied.
• Calibration of temperature-sensitive sensors (e.g., thermistors, RTDs) against NIST-traceable references using multi-point soak-and-hold procedures.

FAQ

Can the HJ-A6 accommodate oversized or irregularly shaped vessels?
Yes—within dimensional limits. The 46 × 32 cm surface area and 12 cm depth permit placement of vessels up to 200 mm in diameter, provided they maintain ≥10 mm clearance from side walls and bottom for effective convection and stir bar mobility.
Is the stirring speed digitally controllable per position?
No—the HJ-A6 provides individual on/off switching and coarse speed adjustment per station via analog potentiometers; fine-grained digital speed programming requires external motor controllers.
What maintenance is required to sustain temperature accuracy over time?
Annual verification using a calibrated reference thermometer (e.g., Fluke 1523 with dry-well calibrator) is recommended. Cleaning the stainless-steel bath with deionized water and mild detergent after each use prevents mineral buildup that could impair thermal coupling.
Does the unit include overtemperature protection?
Yes—a redundant bimetallic thermal cutoff (105 °C nominal trip point) disconnects power if primary control fails, preventing dry-run damage or boiling-over incidents.
Can it be operated continuously for 72+ hours?
Yes—designed for unattended operation under ambient conditions ≤30 °C and relative humidity ≤80% non-condensing, provided proper ventilation and water level monitoring are maintained.