Great Wall DHJF-1230 Ultra-Low Temperature Circulating Cooling Bath

Overview

The Great Wall DHJF-1230 Ultra-Low Temperature Circulating Cooling Bath is an engineered solution for sustained, stable cryogenic thermal management in laboratory-scale chemical synthesis, low-temperature reaction kinetics, and material property characterization. Designed around a single-stage compression cascade architecture with serial interstage heat exchange, the system achieves operational temperatures as low as –120°C without requiring liquid nitrogen or multi-compressor staging. Its core thermodynamic configuration employs a Panasonic hermetic scroll compressor coupled with an air-cooled finned-tube condenser featuring oxygen-free copper coils and proprietary tube-expansion bonding—ensuring high heat transfer coefficients and long-term mechanical integrity under repeated thermal cycling. The refrigerant circuit utilizes a custom-blended zeotropic mixture optimized for wide-range saturation behavior across –120°C to –60°C, enabling precise evaporator superheat control and consistent cooling capacity delivery. The bath reservoir integrates a submerged coil-type evaporator, eliminating risk of mechanical failure during cryogenic solidification of heat transfer fluids—a critical design distinction for uninterrupted operation with ethylene glycol/water or specialized low-temperature oils.

Key Features

• Single-compressor, serial-interstage cascade refrigeration system delivering –120°C minimum operating temperature with no external cryogen dependency
• Panasonic hermetic scroll compressor with integrated thermal overload protection and flexible mounting to mitigate vibration-induced fatigue
• Air-cooled condenser with oxygen-free copper microfinned tubing and proprietary mechanical expansion bonding—enhancing thermal efficiency and service accessibility
• Immersed coil evaporator fully enclosed within the 30 L 304 stainless steel bath tank; mechanically isolated from ice formation stresses
• Digital microprocessor controller with 0.1°C resolution temperature display, intuitive keypad interface, and real-time status feedback
• Stainless steel (304) circulation pump rated for continuous duty at –120°C, delivering 20 L/min flow at 0.4 bar maximum head pressure
• Comprehensive safety architecture: phase-sequence monitoring, overcurrent cutoff, dual-stage thermal protection, delayed startup sequencing, and automatic shutdown on sensor fault
• Full-welded refrigerant circuitry with minimized brazed joints—reducing leak potential and supporting ISO 5149-compliant field servicing

Sample Compatibility & Compliance

The DHJF-1230 accommodates standard laboratory glassware up to 10 L volume via its Ø320 mm bath opening and reinforced Ø400 × 235 mm cylindrical reservoir. All wetted surfaces—including pump housing, circulation lines, and bath interior—are fabricated from ASTM A240 Type 304 stainless steel, ensuring compatibility with common organic solvents, halogenated media, and low-temperature heat transfer fluids (e.g., Dowtherm J, Therminol LT). The unit conforms to IEC 61000-6-3 (EMC emission limits) and IEC 61000-6-2 (immunity requirements), and its electrical safety design complies with IEC 61010-1 for laboratory equipment. While not certified for GMP manufacturing environments, the system supports GLP-aligned documentation workflows through its deterministic control logic and non-volatile parameter storage—enabling traceable setpoint logging and alarm history review per internal SOPs.

Software & Data Management

The DHJF-1230 operates via embedded firmware without external PC dependency. All operational parameters—including set temperature, actual bath temperature, pump status, compressor run time, and active safety flags—are retained in non-volatile memory across power cycles. The controller supports manual calibration offset entry for temperature sensor drift correction, aligning with ISO/IEC 17025 metrological traceability practices. Though lacking native USB/Ethernet connectivity or FDA 21 CFR Part 11-compliant audit trails, the unit’s deterministic behavior and fixed-state control architecture facilitate integration into validated process environments when paired with external data loggers meeting NIST-traceable calibration standards. User-accessible settings are protected by a two-level password system to prevent unauthorized configuration changes during routine operation.

Applications

• Low-temperature Grignard, organolithium, and lithiation reactions requiring strict thermal control between –100°C and –60°C
• Cryogenic crystallization studies of pharmaceutical intermediates and chiral compounds
• Thermal stability testing of battery electrolytes and solid-state electrolyte films
• Calibration of cryogenic sensors and reference thermometers per ITS-90 protocols
• Condensation trapping in vacuum distillation and rotary evaporation setups
• Material testing of elastomers, adhesives, and polymer blends under sub-glass transition conditions

FAQ

Can external circulation be used below –90°C?
No. The system firmware disables the circulation pump when bath temperature falls below –90°C to prevent mechanical stress on the pump and potential fluid phase separation in the external loop.

What heat transfer fluids are compatible with the DHJF-1230?
Ethylene glycol/water mixtures (up to 60% glycol), silicone oils (e.g., DC-200 series), and specialty low-temperature fluids such as Therminol LT or Dowtherm J—provided they remain liquid and non-corrosive within the –120°C to –60°C range.

Is the unit suitable for cleanroom installation?
It is not classified for ISO Class 5 or higher cleanrooms due to fan-driven air-cooling and lack of HEPA-filtered exhaust. However, it may be installed in controlled ambient labs meeting ISO 14644-1 Class 8 requirements with appropriate ventilation planning.

Does the controller support RS-485 or Modbus communication?
No. The DHJF-1230 features standalone operation only; no digital communication interfaces are provided.

What maintenance intervals are recommended for the refrigeration system?
Compressor oil inspection every 24 months; condenser coil cleaning every 6 months in dusty environments; annual verification of refrigerant charge integrity using manifold gauge set and superheat measurement per ASHRAE Guideline 3-2021.