Great Wall DL30-700 Closed-Circuit Recirculating Chiller

Overview

The Great Wall DL30-700 is a high-performance, closed-loop recirculating chiller engineered for precise temperature control in laboratory and analytical instrumentation applications. It operates on the vapor-compression refrigeration cycle, utilizing R410A — a zero-ozone-depletion-potential (ODP), low-global-warming-potential (GWP) hydrofluorocarbon refrigerant compliant with international environmental regulations and China’s GB/T 7778–2017 standard for refrigerants. Designed for continuous operation under ambient conditions of 5–35°C and ≤70% relative humidity, the unit delivers stable cooling across a wide operating range of −30°C to +5°C, with thermal stability maintained within ±2°C under steady-state load. Its core architecture integrates a Panasonic Wakō scroll-type rotary compressor — selected for high volumetric efficiency, low mechanical vibration, and extended service life — coupled with an air-cooled finned-tube condenser featuring oxygen-free copper spiral tubing and proprietary expansion joint technology for enhanced heat transfer and field-serviceability. The evaporator is a coil-type design fully immersed in the stainless steel reservoir, eliminating risk of mechanical damage during low-temperature operation or accidental freezing of the heat-transfer fluid.

Key Features

• Hermetically sealed circulation loop constructed from SUS304 stainless steel, minimizing evaporation loss and preventing contamination of heat-transfer media (e.g., water, water-glycol mixtures, or specialized low-temperature fluids).
• Integrated in-line particulate filter protects downstream equipment (e.g., spectrophotometers, HPLC columns, laser sources) from debris-induced blockage or flow restriction.
• Danfoss DML-series dryer filter with 3A molecular sieve desiccant ensures deep moisture removal, inhibits acid formation from refrigerant degradation, and safeguards compressor longevity and system integrity.
• High-efficiency stainless steel shielded circulation pump rated for continuous duty at sub-zero temperatures with zero leakage, meeting ISO 20816-1 vibration severity thresholds for laboratory-grade pumps.
• Microprocessor-based controller with full-digit LED display provides intuitive setpoint programming, real-time monitoring of bath temperature, system pressure, and reservoir level via integrated visual gauge.
• Comprehensive safety suite includes delayed compressor restart, earth-leakage circuit interruption (ELCI), overcurrent protection, and dual-stage overtemperature cutoff — all compliant with IEC 61010-1:2010 for electrical safety in laboratory environments.

Sample Compatibility & Compliance

The DL30-700 is compatible with a broad spectrum of heat-transfer fluids, including deionized water, 30–50% aqueous ethylene glycol solutions, and low-viscosity synthetic oils approved for −40°C service. Its sealed architecture and corrosion-resistant wetted materials (SUS304 reservoir, copper-alloy heat exchangers, EPDM seals) ensure long-term compatibility with chemically aggressive media used in spectroscopy, calorimetry, and material testing setups. The unit meets GB 4706.1–2005 (Chinese national standard for household and similar electrical appliances), conforms to CE marking requirements under the Low Voltage Directive (2014/35/EU) and EMC Directive (2014/30/EU), and supports GLP/GMP-aligned operational traceability when paired with external data loggers (e.g., compliant with FDA 21 CFR Part 11 for audit trail generation).

Software & Data Management

While the DL30-700 operates as a standalone instrument with no built-in Ethernet or USB connectivity, its analog output (0–5 V or 4–20 mA optional) enables integration into centralized lab monitoring systems (e.g., LabVIEW, DeltaV, or Siemens Desigo CC). The microcontroller retains last-set parameters through power interruption and logs cumulative runtime hours — a critical feature for preventive maintenance scheduling per ISO/IEC 17025:2017 Clause 6.4.2. Optional RS485 Modbus RTU interface (add-on module) allows remote readout of temperature, pressure, and fault status for inclusion in LIMS or CMMS platforms.

Applications

This chiller serves as a primary thermal management solution for instruments requiring consistent low-temperature coolant delivery, including but not limited to: UV-Vis and FTIR spectrophotometers with Peltier-cooled detectors; X-ray diffractometers (XRD) with cryo-stages; high-resolution mass spectrometers (HRMS) requiring source cooling; semiconductor probing stations; rheometers with Peltier-controlled sample holders; and vacuum deposition systems where condenser temperature stability directly impacts film uniformity. Its −30°C capability supports cryogenic sample preparation workflows in polymer characterization and battery electrolyte testing labs.

FAQ

What is the minimum recommended heat-transfer fluid volume for stable operation?
The reservoir holds 17 L nominal capacity; for optimal thermal inertia and pump priming, maintain fluid level ≥70% (≥12 L) during operation.
Can the DL30-700 be used with organic solvents such as acetone or ethanol?
No — only water-based or glycol-based fluids compatible with stainless steel, copper, and EPDM are permitted. Organic solvents may degrade seals and compromise system integrity.
Is external pressure regulation required for connecting to sensitive instruments?
No — the built-in pressure gauge and fixed-output pump (0.4 bar max) eliminate need for external regulators; however, a pressure-reducing valve is advised if downstream instrumentation specifies <0.2 bar inlet pressure.
How often should the Danfoss DML dryer filter be replaced?
Under continuous operation with clean, pre-filtered coolant, replacement is recommended every 18–24 months or after 4,000 operating hours, per Danfoss service bulletin DML-SB-2022-01.
Does the unit support remote start/stop via dry contact signal?
Yes — terminal block inputs for external 24 VDC dry-contact control are available as factory-configurable option (Order Code: DL30-700-RC).