Great Wall DL30-1000 Closed-Circuit Recirculating Chiller

Overview

The Great Wall DL30-1000 is a high-reliability, closed-loop recirculating chiller engineered for continuous thermal management of laboratory instruments requiring precise low-temperature operation. It operates on the vapor-compression refrigeration cycle, utilizing R410A — an environmentally compliant, zero-ozone-depletion-potential (ODP) refrigerant — to achieve stable cooling across a wide operational range from −30 °C to +5 °C. Designed specifically for integration with analytical equipment such as spectrophotometers, ICP-OES systems, laser sources, and vacuum pumps, the unit maintains thermal equilibrium via forced convection through a sealed circulation loop. Its temperature stability of ±2 °C under dynamic load conditions ensures reproducible experimental outcomes in environments where ambient fluctuations would otherwise compromise measurement integrity. The chiller’s architecture prioritizes mechanical robustness and long-term serviceability, with all critical components selected for durability under sustained low-temperature duty cycles.

Key Features

• Hermetically sealed Panasonic Wanbao rotary vane compressor — compact footprint, low acoustic emission (<58 dB(A)), high volumetric efficiency, and extended service life under continuous operation.
• High-efficiency air-cooled finned-tube condenser with oxygen-free copper spiral tubing and proprietary tube-to-fin expansion bonding — optimized heat transfer coefficient (>45 W/m²·K), reduced footprint, and simplified maintenance access.
• Immersion-type coil evaporator integrated directly into the 30 L SUS304 stainless steel reservoir — eliminates risk of coil rupture during coolant freezing events and enables uniform thermal distribution within the bath medium.
• Danfoss DML-series desiccant filter with 13X molecular sieve core — moisture removal capacity <10 ppmv, acid scavenging capability, and system-level protection against hydrolysis-induced corrosion and capillary blockage.
• Sealed stainless steel canned motor pump rated for cryogenic service — zero fluid leakage at −30 °C, flow consistency ±3% across full pressure range, and IP55 ingress protection.
• Fully enclosed circulation path with dual-stage filtration (5 µm particulate + activated carbon adsorption) — prevents particulate ingress into connected instrumentation and extends service intervals for downstream devices.
• Integrated analog pressure gauge and illuminated liquid level indicator — real-time monitoring of system hydraulic state without requiring external instrumentation.
• Microprocessor-based PID controller with digital setpoint adjustment, auto-tuning capability, and non-volatile parameter storage — supports repeatable ramp-hold profiles and retains configuration after power interruption.

Sample Compatibility & Compliance

The DL30-1000 is compatible with standard laboratory heat-transfer fluids including water-glycol mixtures (up to 40% v/v), ethanol/water blends, and silicone-based secondary coolants. It meets GB/T 10870–2014 (Chinese national standard for refrigeration equipment performance testing) and complies with RoHS Directive 2011/65/EU regarding hazardous substance restrictions. While not certified to UL/CSA or CE for North American or EU end-use markets, its electrical safety design incorporates double insulation, reinforced grounding continuity, and Class I protection against electric shock per IEC 61010-1:2010 Ed.3 requirements for laboratory equipment. All refrigerant handling procedures conform to ISO 5149-2:2014 standards for hermetic system charging and recovery.

Software & Data Management

The unit operates autonomously via its embedded microcontroller and does not feature network connectivity, USB ports, or proprietary software interfaces. All operational parameters — setpoint temperature, actual bath temperature, compressor status, and fault codes — are displayed on a 4-digit LED screen with Chinese-language prompts. Event logging is limited to non-volatile storage of the last five alarm triggers (e.g., “E03 Overtemp”, “E07 Low Flow”) with timestamp retention up to 72 hours. For laboratories operating under GLP or GMP frameworks, manual logbook entries must be maintained to satisfy audit requirements for temperature traceability and intervention history. No FDA 21 CFR Part 11 compliance is provided due to absence of electronic signature capability or audit trail functionality.

Applications

This chiller serves as a primary cooling source for applications demanding stable sub-ambient thermal control: spectroscopic sample cells in UV-Vis and FTIR systems; detector housings in Raman spectrometers; condenser jackets in rotary evaporators; cold traps in vacuum manifolds; and thermal regulation of high-power LED light sources used in fluorescence microscopy. It is routinely deployed in QC labs performing ASTM D97 (pour point determination), ISO 3104 (kinematic viscosity), and USP environmental monitoring protocols where ambient temperature excursions could invalidate calibration baselines. Its sealed reservoir design also supports use in cleanroom-adjacent spaces where open-bath chillers pose contamination risks.

FAQ

What is the minimum allowable ambient temperature for continuous operation?
The unit requires ambient conditions between 5 °C and 35 °C. Operation below 5 °C may impair oil return to the compressor and is not recommended.
Can this chiller be used with deionized water only?
Yes, but prolonged use of pure DI water is discouraged due to potential galvanic corrosion in mixed-metal circuits; a 20–30% propylene glycol mixture is preferred for corrosion inhibition and freeze margin.
Is the reservoir volume adjustable or expandable?
No. The 30 L capacity is fixed and integral to the chassis; external reservoirs are not supported by the pump hydraulics or control logic.
Does the unit include a drain valve for coolant replacement?
Yes — a front-panel located quick-release valve enables full reservoir evacuation without disassembly.
What maintenance intervals are recommended for the Danfoss filter?
Under normal lab use with clean coolant, replace the DML filter cartridge every 12 months or after 2000 operating hours — whichever occurs first.