Zhengzhou Great Wall Scientific Industrial & Trading Co., Ltd. DHJF-1210 Low-Temperature Constant-Temperature Stirred Reaction Bath

Overview

The Zhengzhou Great Wall Scientific Industrial & Trading Co., Ltd. DHJF-1210 Low-Temperature Constant-Temperature Stirred Reaction Bath is an engineered laboratory system designed for precise thermal control and mechanical agitation in cryogenic synthetic and analytical workflows. It operates on a single-stage vapor-compression refrigeration cycle enhanced by series-connected subcooling heat exchange — a design that enables stable operation down to −120 °C without cascaded compressors. Unlike conventional low-temperature baths relying on dual-stage or liquid nitrogen supplementation, the DHJF-1210 achieves deep-cold performance through optimized thermodynamic staging within a fully welded refrigerant circuit, minimizing leak paths and maximizing long-term reliability under continuous duty. Its integrated magnetic stirring mechanism allows simultaneous temperature regulation and homogeneous mixing — critical for exothermic low-temperature reactions, crystallization studies, and low-T kinetic investigations where thermal gradients must be minimized across the reaction volume.

Key Features

• Hermetically sealed Tecumseh/TaiKang piston compressor with low-noise, high-efficiency operation and extended service life under sustained cryogenic load.
• Air-cooled condenser featuring oxygen-free copper finned tubing for superior heat rejection and corrosion resistance in standard lab environments.
• Series-connected subcooling heat exchanger architecture enabling −120 °C bath stability using only one compressor — reducing complexity, maintenance points, and failure probability.
• Immersion-type coil evaporator fully submerged in the 304 stainless steel bath reservoir; mechanically isolated from thermal stress during cryogen-induced phase transitions of heat transfer fluid.
• Digital microprocessor controller with 0.1 °C temperature resolution, real-time display, and programmable ramp/soak profiles for reproducible thermal protocols.
• Integrated 50 W magnetic stirrer with adjustable speed (100–1000 rpm), compatible with standard PTFE-coated stir bars and glass reactor vessels up to 3000 mL capacity.
• Comprehensive safety suite including delayed compressor restart, overcurrent cutoff, and dual-sensor overtemperature interlock — compliant with IEC 61010-1 requirements for laboratory equipment.

Sample Compatibility & Compliance

The DHJF-1210 accommodates standard round-bottom flasks (up to 3 L), jacketed reactors, and custom immersion probes via its Ø210 mm open-top bath configuration. The 304 stainless steel reservoir resists corrosion from common low-temperature heat transfer media including ethanol/methanol mixtures, silicone oils, and specialized cryogenic fluids. All electrical components meet CE marking requirements per EN 61000-6-3 (EMC) and EN 61000-6-4 (immunity). While not certified to UL or CSA standards out-of-the-box, the unit’s architecture supports third-party validation for GLP/GMP environments when operated within specified ambient conditions (5–35 °C, ≤70% RH) and documented maintenance intervals. Its temperature stability (±2 °C across the full −120 °C to −60 °C range) meets typical requirements for ASTM D5296 (polymer molecular weight distribution by SEC at low T) and ISO 6271 (low-temperature viscosity measurement).

Software & Data Management

The DHJF-1210 operates via embedded firmware with no external PC dependency; however, optional RS485/Modbus RTU interface (available upon request) enables integration into centralized lab automation systems. When interfaced, users may log temperature setpoints, actual bath temperature, stirring speed, and alarm events at user-defined intervals (1–60 s) — supporting audit-ready data capture for FDA 21 CFR Part 11–aligned workflows when paired with validated SCADA or LIMS platforms. Local event logging includes timestamped records of all safety interventions (e.g., overtemperature shutdown), facilitating root-cause analysis during QA/QC reviews. Firmware updates are performed via secure USB interface with version-controlled binaries traceable to manufacturer release notes.

Applications

• Low-temperature organic synthesis requiring strict thermal control below −80 °C (e.g., organolithium additions, Diels–Alder cycloadditions).
• Cryogenic material testing: thermal contraction analysis of polymers, composites, and electronic substrates.
• Calibration of low-temperature sensors (RTDs, thermistors) against NIST-traceable reference standards.
• Preparative chromatography at sub-zero temperatures to enhance selectivity in chiral separations.
• Controlled freezing studies for biopharmaceutical formulation development (e.g., lyophilization cycle scouting).
• Physical property measurements including cryogenic viscosity, density, and dielectric constant of specialty fluids.

FAQ

What refrigerant is used in the DHJF-1210, and is it compliant with current environmental regulations?
The unit employs a proprietary zeotropic mixture of HFCs selected for optimal low-temperature performance and compatibility with hermetic compressors. This blend has zero ozone depletion potential (ODP = 0) and is classified as non-flammable (ASHRAE A1). While not subject to EU F-Gas Phase-down quotas due to its closed-loop design and <1 kg charge, end-of-life recovery must follow local refrigerant handling statutes.

Can the DHJF-1210 maintain −120 °C continuously with stirring active?
Yes — the system is rated for continuous operation at −120 °C with magnetic stirring engaged at any speed between 100–1000 rpm. Actual achievable temperature depends on ambient conditions, bath fluid volume, and thermal load from immersed apparatus; full 10 L fill with minimal external heat ingress yields nominal −120 °C stability.

Is the stainless steel bath resistant to methanol/ethanol-based coolants at −120 °C?
AISI 304 stainless steel retains ductility and corrosion resistance down to −196 °C in anhydrous alcohols. However, trace water content (>50 ppm) in coolant mixtures may induce pitting at prolonged exposure; users are advised to monitor fluid purity and replace annually under continuous use.