The Great Wall DL-400 Circulating Chiller

Overview

The Great Wall DL-400 Circulating Chiller is an integrated, air-cooled refrigeration system engineered for precise thermal management in laboratory environments. It operates on a vapor-compression cycle using environmentally compliant R134a refrigerant and delivers stable, continuous cooling to external equipment via a closed-loop circulation of deionized water or aqueous glycol solutions. Designed specifically to support low-heat-load applications—including benchtop rotary evaporators, condenser jackets, spectrophotometer Peltier modules, and small-scale reaction calorimeters—the DL-400 maintains temperature setpoints within ±2 °C across its full operating range of −15 °C to +25 °C. Its compact footprint (260 × 410 × 550 mm), stainless steel (SUS304) reservoir, and 3 L working volume enable seamless integration into space-constrained fume hoods or instrument benches without compromising structural integrity or corrosion resistance.

Key Features

• Integrated air-cooled architecture eliminates need for external cooling water infrastructure—ideal for labs lacking chilled-water supply or where plumbing modifications are impractical.
• High-visibility LCD display with 0.1 °C resolution and Pt100 RTD sensor ensures accurate real-time monitoring of reservoir temperature and system status.
• 360° rotatable fluid coupling ports simplify hose routing and reduce mechanical stress during connection to rotary evaporators, reflux condensers, or analytical instrumentation.
• Multi-layer safety architecture includes compressor delay start (prevents voltage surge damage), thermal overload protection, and dual-stage overcurrent circuit interruption—fully compliant with IEC 61000-4 electromagnetic compatibility standards.
• Low-noise centrifugal circulation pump delivers consistent 17 L/min flow at 0.2 bar pressure, supporting laminar flow conditions required for efficient heat exchange in jacketed glassware and inline chillers.
• TÜV-certified CE marking confirms conformity with EU Machinery Directive 2006/42/EC and Low Voltage Directive 2014/35/EU—documented in technical file available upon request for GLP/GMP audit preparation.

Sample Compatibility & Compliance

The DL-400 is compatible with standard laboratory heat-transfer fluids including deionized water, 30% aqueous propylene glycol, and other non-corrosive, low-viscosity coolants. Its SUS304 reservoir and internal wetted components resist oxidation and leaching under prolonged exposure to pH-neutral or mildly alkaline media. While not rated for explosive atmospheres or pharmaceutical-grade sterile operation, the unit meets essential requirements for routine QC/QA workflows in chemical synthesis, polymer characterization, and materials testing laboratories. It supports compliance with ISO/IEC 17025:2017 clause 6.4.8 (environmental condition control) when deployed within ambient lab conditions of 5–35 °C and ≤70% relative humidity. No hazardous substance declarations (RoHS, REACH) are required for R134a usage per EU Regulation (EC) No 1005/2009 Annex I exemptions.

Software & Data Management

The DL-400 operates as a standalone analog-controlled chiller without digital communication interfaces (e.g., RS-232, USB, or Ethernet). All operational parameters—including setpoint, actual temperature, pump status, and fault codes—are displayed locally via the front-panel LCD. For laboratories requiring electronic data capture, third-party analog-to-digital loggers (e.g., Omega OM-DAQPRO-5300 series) may be connected to the optional 0–5 V analog output (available on custom-configured units) to record temperature trends and generate audit-ready CSV files. Though lacking native 21 CFR Part 11 functionality, the unit’s mechanical reliability, TÜV-certified safety logic, and traceable calibration history (via factory-issued certificate) support integration into validated systems under FDA-regulated environments when paired with appropriate procedural controls.

Applications

• Cooling bath for rotary evaporation of solvents with boiling points below 80 °C (e.g., dichloromethane, ethyl acetate, acetone).
• Condenser jacket cooling in fractional distillation setups requiring sub-ambient reflux temperatures.
• Thermal stabilization of UV-Vis spectrophotometer sample compartments during extended kinetic assays.
• Temperature regulation for benchtop HPLC column ovens operating below ambient setpoints.
• Support cooling for small-scale electrochemical cells and battery testing rigs with moderate heat dissipation (<400 W).
• Pre-chilling of reagents prior to cryogenic reaction initiation in organic synthesis workflows.

FAQ

What is the minimum achievable temperature when using the DL-400 with a rotary evaporator?

The reservoir can reach −15 °C under nominal ambient conditions (25 °C, 50% RH); however, effective cooling at the evaporator condenser depends on flow rate, tubing length, and heat load—typical endpoint temperatures range between −5 °C and +5 °C.
Can the DL-400 operate continuously for 24/7 unattended use?

Yes—designed for continuous-duty operation with thermal cutouts and compressor cycling logic to prevent overheating; recommended for maximum 18 h/day duty cycles in high-humidity environments (>60% RH) to avoid condensate accumulation in the condenser coil.
Is the unit suitable for use with flammable solvents like ether or pentane?

No—while the chiller itself contains no ignition sources, it is not ATEX- or UL-classified for hazardous locations; use only with non-flammable coolants and ensure external equipment complies with local fire codes.
Does the DL-400 require regular refrigerant servicing?

No—hermetically sealed R134a system requires no scheduled recharge under normal operation; annual visual inspection of condenser fins and fan operation is recommended for optimal efficiency.
What maintenance is required for the circulating pump?

The brushless DC pump is maintenance-free for ≥10,000 hours; periodic flushing with deionized water every 6 months prevents mineral buildup when using tap water-based coolants.