The Great Wall DLSB-5/20D Low-Temperature Circulating Chiller

Overview

The Great Wall DLSB-5/20D Low-Temperature Circulating Chiller is an integrated, air-cooled refrigeration system engineered for precise thermal management in laboratory and pilot-scale applications. It operates on a vapor-compression cycle using R404A refrigerant, delivering stable cooling output across a wide operational range from –20 °C to +25 °C. Designed for continuous duty in controlled ambient conditions (5–35 °C, ≤70% RH), the unit maintains consistent temperature setpoints via PID-controlled compressor modulation and a high-efficiency finned-tube condenser. Its primary function is to supply externally recirculated coolant—typically water or aqueous glycol mixtures—to process equipment requiring active heat extraction, including rotary evaporator condensers, jacketed reactors, material testing chambers, laser diode mounts, and semiconductor thermal test fixtures. Unlike immersion-style cold baths, the DLSB-5/20D separates reservoir volume from thermal load interface, enabling closed-loop circulation with minimal evaporation loss and improved long-term fluid integrity.

Key Features

• Integrated air-cooled architecture with compact footprint (335 × 473 × 684 mm) and stainless steel 304 reservoir for corrosion resistance and chemical compatibility
• LCD front-panel display with 0.1 °C resolution and real-time monitoring of setpoint, actual bath temperature, and system status indicators
• RS485 serial interface compliant with Modbus RTU protocol, supporting integration into centralized lab automation systems or SCADA networks for remote parameter adjustment and alarm logging
• Multi-layer protection suite: compressor delay-start (prevents short-cycling), overcurrent cutoff, high-pressure cutout, overtemperature shutdown, grounding fault detection, and dry-run prevention for pump safety
• Optimized hydraulic design featuring a magnetically coupled centrifugal circulation pump capable of sustaining up to 22 L/min flow at 1.1 bar maximum head pressure, compatible with standard 1/2″ fittings and silicone tubing (Φ13 × Φ9 mm)
• CE-marked per applicable EN 61000-6-2 (EMC immunity) and EN 61000-6-4 (EMC emission) standards; TÜV-certified models meet essential safety requirements under the Low Voltage Directive (2014/35/EU)

Sample Compatibility & Compliance

The DLSB-5/20D circulates non-corrosive, low-viscosity heat-transfer fluids—including deionized water, 30% ethylene glycol/water blends, or specialized silicone oils—within closed-loop configurations. Its SS304 reservoir and internal wetted components ensure compatibility with common organic solvents and mild acidic/basic media encountered in pharmaceutical synthesis, polymer characterization, and analytical sample preparation. While not classified as a medical device or GMP-grade instrument, the chiller supports Good Laboratory Practice (GLP) workflows through traceable temperature control and configurable alarm thresholds. Its Modbus interface facilitates audit-ready data capture when paired with validated data acquisition software, aligning with documentation expectations for ISO/IEC 17025-accredited laboratories. No intrinsic explosion-proof rating is provided; operation in hazardous locations requires external classification and engineering controls.

Software & Data Management

The DLSB-5/20D does not include proprietary PC software but delivers native interoperability via its open Modbus RTU implementation. Users may configure third-party SCADA platforms (e.g., Ignition, LabVIEW, or custom Python-based DAQ systems) to poll real-time values—including temperature setpoint, measured bath temperature, pump status, and fault codes—as well as issue write commands for setpoint adjustment or system reset. All communication occurs over standard RS485 wiring with configurable baud rates (9600–115200 bps), parity, and slave ID. For standalone operation, the embedded controller logs critical events (e.g., overtemperature trips, compressor lockouts) with timestamped entries accessible via front-panel navigation. No built-in data storage or FDA 21 CFR Part 11 compliance features are included; electronic record integrity must be ensured at the supervisory system level.

Applications

• Cooling condenser jackets of rotary evaporators during solvent removal under reduced pressure, minimizing bumping and improving distillate recovery
• Temperature stabilization of calorimetric cells, rheometers, and differential scanning calorimeters (DSC) during dynamic thermal analysis
• Thermal conditioning of photovoltaic cell test benches and LED aging chambers under programmable ramp-and-soak profiles
• Heat sink management for continuous-wave (CW) solid-state lasers and optical parametric oscillators (OPOs) requiring sub-ambient junction temperature control
• Simulating low-temperature process environments in catalysis studies, crystallization kinetics experiments, and cryo-microscopy sample stages
• Direct immersion cooling of reaction flasks, centrifuge rotors, or electrophoresis tanks where precise bath temperature maintenance is critical

FAQ

What is the minimum achievable temperature at full load?
Under nominal ambient conditions (25 °C, 50% RH), the DLSB-5/20D achieves –20 °C at no-flow (static) conditions. At maximum flow (22 L/min), the practical lower limit is approximately –15 °C due to thermal loading from pump work and heat ingress.

Can this unit operate continuously for 72+ hours?
Yes. The DLSB-5/20D is rated for unattended 24/7 operation when installed in a well-ventilated space meeting specified ambient limits (5–35 °C). Compressor cycling and thermal protection logic prevent thermal runaway during extended duty cycles.

Is R404A refrigerant serviceable in the field?
R404A charging and leak repair require certified HVAC-R technicians licensed under EPA Section 608 (or equivalent national regulation). The unit is factory-charged and sealed; end users should not attempt refrigerant handling without proper certification and recovery equipment.

Does the chiller support external temperature feedback control?
No. The DLSB-5/20D regulates temperature solely via its internal Pt100 sensor immersed in the reservoir. External probe input or cascade control functionality is not supported in firmware.

What maintenance intervals are recommended?
Inspect air intake filters monthly; clean condenser coils quarterly; verify coolant level and clarity biannually; replace circulating fluid every 12 months or sooner if discoloration or particulate formation is observed.