The Great Wall DHJF-1005 Low-Temperature Constant-Temperature Stirred Reaction Bath

Overview

The Great Wall DHJF-1005 Low-Temperature Constant-Temperature Stirred Reaction Bath is an engineered solution for precise thermal control in cryogenic chemical synthesis, low-temperature catalysis, and material property characterization. Unlike conventional cascade refrigeration systems requiring multiple compressors, the DHJF-1005 implements a proprietary single-stage compression with fractional condensation technology—enabling stable operation down to −100 °C using only one high-efficiency hermetic compressor. This architecture eliminates the complexity, leak-prone weld joints, and elevated maintenance burden associated with triple-stage cascade designs. The system employs a coiled evaporator integrated with a series-connected multi-section condenser assembly: an outer evaporator tube houses segmented inner condensing tubes, enabling thermodynamic staging within a single refrigerant loop. This design delivers enhanced reliability, reduced footprint, and lower total cost of ownership while maintaining consistent thermal output across demanding reaction protocols.

Key Features

• Single-compressor ultra-low-temperature refrigeration system capable of sustained operation from −100 °C to −60 °C
• Digital PID temperature controller with intuitive interface, real-time setpoint adjustment, and ±2 °C stability over full operating range
• External circulation pump (flow rate up to 15 L/min, pressure head ≥ 0.2 MPa) compatible with jacketed reactors, condensers, and custom heat exchangers
• 5 L stainless steel (SUS304) bath reservoir with corrosion-resistant polymer-coated internal surfaces and cryo-compatible gasketing
• Hermetically sealed refrigeration circuit using R23/R508B mixed refrigerant blend; critical components sourced from Tier-1 European and U.S. suppliers (compressor, expansion valve, oil separator)
• Integrated magnetic stirring function (optional upgrade) with speed regulation (0–1200 rpm) and torque compensation for viscous media
• Thermal insulation optimized for ambient conditions between 5 °C and 25 °C; power input: 220 V / 50 Hz, 820 W nominal

Sample Compatibility & Compliance

The DHJF-1005 supports immersion of standard laboratory glassware—including 2 L round-bottom flasks—within its Φ210 mm opening and 180 mm bath depth. Its fluid path materials (SUS304, PTFE-lined tubing, EPDM low-temp seals) ensure compatibility with common organic solvents (e.g., THF, acetone, liquid N₂–cooled baths), halogenated media, and aqueous electrolytes under cryogenic conditions. The unit conforms to IEC 61010-1:2010 for electrical safety in laboratory equipment and meets CE marking requirements for EMC (EN 61326-1) and low-voltage directives. While not certified for GMP production environments, its temperature logging capability (via optional RS485/Modbus interface) supports GLP-aligned experimental documentation when paired with validated third-party data acquisition software.

Software & Data Management

The DHJF-1005 operates via embedded firmware with local keypad-and-display control. For extended data integrity, it supports analog voltage output (0–5 V) proportional to bath temperature and digital communication via RS485 Modbus RTU protocol. When interfaced with compliant SCADA or LIMS platforms (e.g., LabVIEW, DeltaV, or custom Python-based acquisition tools), users can implement automated temperature ramps, alarm-triggered shutdowns, and time-stamped audit trails meeting FDA 21 CFR Part 11 principles—provided the host system enforces user authentication, electronic signatures, and immutable record storage. Firmware updates are performed via USB port; no cloud connectivity or remote access functionality is included, preserving network security in regulated labs.

Applications

• Cryogenic Grignard and organolithium reactions requiring strict thermal control below −80 °C
• Low-temperature polymerization kinetics studies (e.g., anionic ring-opening of lactides at −95 °C)
• Calibration of infrared detectors and bolometers in metrology laboratories
• Pre-cooling of GC injectors, FTIR sampling cells, and XRD cryostat stages
• Stabilized cooling for superconducting magnet test benches and quantum device characterization rigs
• Long-duration stability testing of battery electrolytes and solid-state ion conductors

FAQ

What refrigerant does the DHJF-1005 use, and is it ozone-safe?
The unit employs a zeotropic blend of R23 (trifluoro methane) and R508B (a mixture of R23 and R13), both Class I HCFC-free refrigerants with zero ozone depletion potential (ODP = 0) and globally accepted under current Montreal Protocol guidelines.

Can the DHJF-1005 be used with dry ice or liquid nitrogen as auxiliary coolants?
No. The system is designed exclusively for closed-loop refrigerant-based cooling. Introducing cryogens into the bath or circulation loop will damage seals, contaminate the refrigerant circuit, and void the warranty.

Is external stirring integration supported?
Yes. The bath features standardized 1/4″ NPT ports and mounting flanges compatible with commercially available overhead stirrers (e.g., IKA RW 20, Heidolph RZR 2021) via custom adapter plates.

What is the minimum recommended working fluid for −100 °C operation?
A 50:50 (v/v) mixture of ethylene glycol and ethanol, verified for pour point ≤ −105 °C and thermal conductivity > 0.25 W/m·K at −100 °C. Silicone oils are not recommended due to excessive viscosity below −70 °C.

Does the unit include validation documentation for IQ/OQ protocols?
Factory calibration certificates (NIST-traceable reference sensor) are provided. Full IQ/OQ documentation packages—including installation checklists, operational test scripts, and uncertainty budgets—are available upon request for qualified purchasers under separate service agreement.