Zhongjiaojinyuan DL Series Low-Temperature Constant-Temperature Circulating Bath

Overview

The Zhongjiaojinyuan DL Series Low-Temperature Constant-Temperature Circulating Bath is a precision-engineered thermal management system designed for continuous, stable delivery of chilled or temperature-controlled fluid to external laboratory instruments and internal bath applications. Operating on a vapor-compression refrigeration cycle with air-cooled, hermetically sealed compressors, the DL Series delivers reliable cooling performance across four distinct low-temperature tiers: −10 °C, −20 °C, −30 °C, and −60 °C. Unlike passive chillers or dry ice baths, this circulating bath maintains dynamic thermal equilibrium by continuously recirculating conditioned fluid through an integrated reservoir and external loop—enabling precise temperature control for heat-sensitive analytical instrumentation and exothermic reaction systems. Its architecture supports both closed-loop cooling (e.g., condenser jacketing for rotary evaporators) and open-bath immersion testing (e.g., cryogenic sample conditioning), making it integral to synthetic chemistry, materials characterization, and bioprocess development workflows.

Key Features

• Air-cooled, hermetically sealed compressor system with automatic start/stop logic and built-in safeguards—including compressor delay protection, high-temperature cutoff, and overcurrent circuit interruption—to ensure long-term operational integrity.
• Microprocessor-based digital controller with intuitive touch-sensitive soft keys; eliminates mechanical dials and reduces calibration drift risk.
• Dual-color LED display (red for setpoint, green for actual temperature) with 0.1 °C resolution and user-accessible offset correction to compensate for sensor thermal lag or bath gradient effects.
• Programmable timer shutdown function (0–100 hours) for unattended operation during overnight or extended experiments—critical for compliance with laboratory safety protocols and energy conservation policies.
• Software lock mode prevents unauthorized modification of temperature setpoints, timer values, or system configuration parameters—supporting audit readiness under GLP and ISO/IEC 17025 frameworks.
• High-flow, low-pulsation circulation pump (15 L/min at 4 m head) capable of sustaining stable flow rates across pressure drops typical of coiled condensers, jacketed reactors, and multi-port distribution manifolds.

Sample Compatibility & Compliance

The DL Series accommodates a broad range of sample formats and instrument interfaces without requiring custom adapters. Its open-bath design permits direct immersion of flasks, test tubes, cuvettes, and small-scale reactors up to 50 L volume (depending on model). For external cooling, standard 1/2″–3/4″ NPT or BSP fluid ports support connection to rotary evaporators (e.g., Buchi R-300), fermenters, electron microscopes (TEM/SEM cold stages), mass spectrometers (ESI source cooling), and vacuum coating systems. All units are constructed from corrosion-resistant stainless steel and engineered plastics compatible with common heat-transfer fluids (e.g., 30% ethylene glycol/water, silicone oils). While not certified to UL/CSA or CE for North American/EU markets out-of-box, the system’s electrical architecture and safety interlocks align with IEC 61010-1 requirements for laboratory equipment. Documentation packages include traceable calibration certificates for temperature sensors and pump performance verification reports—facilitating internal validation and regulatory submissions.

Software & Data Management

The DL Series operates via embedded firmware with no external PC dependency. All parameter configuration, real-time monitoring, and event logging occur locally on the front-panel interface. The controller records timestamped temperature deviations (>±0.3 °C) and fault codes (e.g., “E02: Compressor Overtemp”) in non-volatile memory, retaining up to 1,000 event entries for retrospective analysis. Though lacking native Ethernet or USB data export, the system supports optional RS-485 Modbus RTU integration (via accessory module) for centralized monitoring in facility-wide SCADA or LIMS environments. Audit trail functionality—required under FDA 21 CFR Part 11 for regulated labs—is implemented via immutable log entries tied to operator ID (assigned via password-protected login), ensuring accountability during QA/QC reviews and regulatory inspections.

Applications

• Cooling condensers and receiving flasks in rotary evaporation setups to maximize solvent recovery and prevent bumping.
• Temperature stabilization of laser sources, CCD detectors, and optical benches in spectroscopy and interferometry.
• Maintaining sub-ambient conditions for low-temperature NMR probe pre-cooling and cryo-EM grid vitrification.
• Providing consistent thermal sinks for calorimetric cells, differential scanning calorimeters (DSC), and rheometers requiring precise thermal ramping.
• Controlling jacket temperature in pilot-scale bioreactors and chemical synthesis reactors to manage exothermic kinetics and improve batch reproducibility.
• Serving as secondary constant-temperature baths for calibrating thermistors, RTDs, and infrared thermometers per ASTM E74 or ISO 17025 procedures.

FAQ

What is the lowest achievable temperature for the DL-6050 model?

The DL-6050 achieves a minimum operating temperature of −60 °C using a cascade refrigeration system; sustained operation at this setpoint requires use of low-freezing-point heat-transfer fluid (e.g., specialized silicone oil).
Can the unit maintain temperature stability during high-flow external circulation?

Yes—the pump and heat exchanger are sized to deliver ±0.1 °C stability at full flow (15 L/min) across typical loop resistances (90° bends.
Is remote monitoring supported without third-party hardware?

No native Wi-Fi or Ethernet interface is included; however, the optional RS-485 Modbus RTU module enables integration with building management systems or LabVIEW-based control platforms.
How often does the system require maintenance?

Compressor oil and refrigerant levels are factory-sealed for life; recommended annual inspection includes cleaning condenser fins, verifying pump seal integrity, and validating temperature sensor accuracy against a NIST-traceable reference.
Does the software lock feature persist after power cycling?

Yes—the lock state and all user-defined parameters are retained in EEPROM and remain active until manually disabled with the correct administrator password.