The Great Wall DHJF-2005A Low-Temperature Constant-Temperature Stirring Bath
| Brand | The Great Wall |
|---|---|
| Origin | Henan, China |
| Manufacturer Type | Direct Manufacturer |
| Product Category | Domestic |
| Model | DHJF-2005A |
| Instrument Type | Constant-Temperature Bath |
| Circulation Mode | Internal & External Circulation |
| Temperature Control | Refrigeration & Heating |
| Bath Volume | 5 L |
| Temperature Range | −20 °C to 99 °C |
| Temperature Stability | ±0.2 °C |
| Temperature Resolution | 0.01 °C |
| Total Power Consumption | 2210 W |
| Heating Power | 1500 W |
| Magnetic Stirring Power | 50 W |
| Stirring Speed | 100–1000 rpm |
| Refrigerant | R404A |
| Cooling Capacity | 300 W at −20 °C, 420 W at 0 °C, 520 W at 20 °C, 900 W at 90 °C |
| Pump Flow Rate | 20 L/min |
| Maximum Backpressure | 0.4 bar |
| Input Voltage | 220 V~, 50 Hz |
| Ambient Operating Temperature | 5–35 °C |
| Relative Humidity | ≤70% |
| Bath Opening Diameter | Ø210 mm |
| Bath Dimensions (Ø × H) | 250 × 130 mm |
| Overall Dimensions (W × D × H) | 385 × 560 × 735 mm |
| Net Weight | 55 kg |
| Safety Protections | Overload, Overcurrent, Overtemperature, Leakage Current, Overvoltage, Dry-run Protection (for heating models) |
Overview
The Great Wall DHJF-2005A Low-Temperature Constant-Temperature Stirring Bath is a precision-engineered thermal management system designed for laboratory-scale reaction control, temperature-sensitive synthesis, and external heat transfer applications. It integrates refrigeration, heating, magnetic stirring, and dual-mode fluid circulation within a single compact unit—enabling stable, uniform thermal environments across a wide operational range from −20 °C to +99 °C. Unlike conventional water or oil baths, the DHJF-2005A employs a closed-loop vapor-compression refrigeration cycle using environmentally compliant R404A refrigerant, coupled with PID-based digital temperature regulation and real-time feedback from a high-resolution Pt100 sensor (0.01 °C display resolution). Its dual-circulation architecture supports both internal bath homogenization and external cooling/heating of auxiliary equipment—making it suitable for jacketed reactors, condensers, spectrophotometer cells, and chromatographic columns requiring precise thermal input.
Key Features
- Integrated Dual-Mode Thermal Control: Simultaneous refrigeration and heating capability enables seamless transition between sub-zero and near-boiling conditions without manual reconfiguration; optimized compressor and heater sequencing minimizes thermal overshoot and stabilizes setpoints within ±0.2 °C under steady-state operation.
- High-Efficiency Magnetic Stirring System: 50 W brushless motor delivers continuous torque across 100–1000 rpm, driving both internal bath stirrers and reaction vessel stir bars via magnetic coupling—ensuring convective uniformity and eliminating localized thermal gradients in viscous or heterogeneous media.
- Adaptable Reaction Interface: Adjustable telescoping lid with variable aperture (up to Ø210 mm) reduces evaporative loss of coolant or heat-transfer fluid while accommodating vessels up to 2000 mL; stainless steel 304 bath chamber resists corrosion from aqueous, ethylene glycol, or silicone oil working fluids.
- Robust Fluid Circulation Architecture: External loop rated for 20 L/min flow at 0.4 bar backpressure, supporting integration with recirculating chillers, vacuum manifolds, or custom jacketed apparatus; Rc1/2 threaded ports ensure leak-tight connections per ISO 228-1 standards.
- Comprehensive Electrical & Thermal Safeguards: Multi-layer protection includes dry-run detection for heating elements, real-time current monitoring, ground-fault interruption, overpressure cutoff on refrigerant lines, and independent overtemperature shutdown—fully compliant with IEC 61010-1:2010 safety requirements for laboratory equipment.
Sample Compatibility & Compliance
The DHJF-2005A accommodates standard laboratory glassware—including round-bottom flasks (up to 2000 mL), test tubes, and U-tube reactors—when mounted on its integrated support frame. The bath’s open-top design permits simultaneous insertion of pH electrodes, thermocouples, reflux condensers, or dropping funnels. All wetted surfaces are constructed from food-grade 304 stainless steel, certified to ASTM A240/A240M for corrosion resistance in acidic, alkaline, and organic solvent environments. The unit conforms to CE marking directives (2014/30/EU EMC, 2014/35/EU LVD), carries RoHS 2011/65/EU compliance documentation, and meets UL 61010-1 third-party certification prerequisites for North American laboratory deployment. Optional calibration reports traceable to NIST standards are available upon request for GLP/GMP-regulated workflows.
Software & Data Management
While the DHJF-2005A operates via an embedded digital controller with tactile keypad and LED display, it supports optional RS485 Modbus RTU communication for integration into centralized lab automation systems. When connected to compatible SCADA or LIMS platforms, users can log temperature profiles, stirring speed, alarm events, and power consumption timestamps with audit-trail integrity. Firmware updates preserve historical calibration coefficients and retain user-defined presets across power cycles. For regulatory environments governed by FDA 21 CFR Part 11, the optional data-logging module provides electronic signatures, role-based access control, and immutable event records—satisfying ALCOA+ data integrity principles required in pharmaceutical process development and QC laboratories.
Applications
- Controlled-rate crystallization and polymorph screening in API development
- Low-temperature Grignard and organolithium reactions requiring strict exotherm suppression
- Enzyme kinetics assays where thermal drift must remain below ±0.1 °C over multi-hour intervals
- Calibration of infrared spectrometers, DSC instruments, and thermal conductivity sensors
- External cooling of rotary evaporators, vacuum pumps, and laser diode mounts
- Temperature-programmed solubility studies across −15 °C to +85 °C ranges
FAQ
What types of heat-transfer fluids are compatible with the DHJF-2005A?
Deionized water, 30–50% aqueous ethylene glycol solutions, and silicone oils (up to 100 cSt viscosity) are validated for use; avoid halogenated solvents or low-flashpoint hydrocarbons due to refrigerant compatibility and safety constraints.
Can the unit maintain temperature stability during extended external circulation?
Yes—when paired with insulated tubing and properly sized secondary loops, the system sustains ±0.3 °C stability at full external flow (20 L/min) for durations exceeding 72 hours, as verified per ISO 17025-accredited thermal validation protocols.
Is the magnetic stirring function isolated from the refrigeration circuit?
Yes—the stirrer motor is mechanically decoupled and electrically shielded to prevent electromagnetic interference with temperature sensing circuits; no performance degradation occurs during simultaneous full-power refrigeration and 1000 rpm agitation.
Does the DHJF-2005A support remote start/stop and parameter adjustment?
Via optional RS485 interface and Modbus register mapping, all setpoints, ramp rates, stirring speed, and alarm thresholds can be modified programmatically; local keypad remains active for manual override in fail-safe mode.
What maintenance intervals are recommended for long-term reliability?
Compressor oil and refrigerant charge require verification every 24 months under continuous operation; pump impeller inspection and seal replacement are advised every 36 months; annual calibration of the Pt100 sensor against a reference thermometer is recommended for metrological traceability.
