ZT-20-200-30H Closed-Loop Refrigerated & Heated Circulator (Air-Cooled) by The Great Wall

Overview

The ZT-20-200-30H Closed-Loop Refrigerated & Heated Circulator (Air-Cooled) is an engineered thermal management system designed for precise, bidirectional temperature control of external laboratory equipment—including jacketed reactors, rotary evaporators, calorimeters, and analytical instrumentation. Operating on a dual-mode thermodynamic cycle, the unit integrates a high-efficiency air-cooled compressor with a resistive heating circuit and a recirculating pump, enabling seamless transition between cooling and heating modes without manual intervention. Its sealed circulation architecture prevents evaporation, oxidation, or contamination of heat-transfer fluids (e.g., silicone oil, ethylene glycol/water mixtures), ensuring long-term fluid integrity and consistent thermal performance across the full operating range of −30 °C to +200 °C. Temperature stability is maintained within ±0.5 °C under dynamic load conditions, meeting the repeatability requirements of synthetic chemistry optimization, crystallization studies, and accelerated stability testing per ICH Q1 guidelines.

Key Features

• Wide operational span: −30 °C to 200 °C in a single unit—eliminating the need for separate chillers and ovens
• Air-cooled design with integrated condenser fan assembly—no external water supply or drainage required
• High-flow, pressure-stable circulation pump (30 L/min @ 1 bar) optimized for low-backpressure external loops up to 15 m tubing length
• Dual independent thermal control: PID-regulated heating (3 kW) and variable-speed compressor-based cooling (R22 refrigerant)
• Stainless steel reservoir and fluid pathways compliant with ISO 8573-1 Class 4 for particulate and moisture control
• Integrated safety systems: over-temperature cutoff, low-level fluid alarm, dry-run protection, and refrigerant pressure monitoring
• Optional explosion-proof configuration available (ATEX/IECEx-certified variants upon request)

Sample Compatibility & Compliance

The ZT-20-200-30H is compatible with standard laboratory heat-transfer media, including Dow Corning PMX-200 silicone oil (−40 °C to 200 °C), Marlotherm SH (−20 °C to 300 °C), and 50/50 ethylene glycol/water (−34 °C to 130 °C). Its closed-loop architecture ensures no exposure of process fluids to ambient atmosphere, supporting GLP-compliant workflows where solvent volatility or moisture sensitivity is critical. The unit complies with IEC 61010-1:2010 for electrical safety in laboratory equipment and meets CE marking requirements for electromagnetic compatibility (EN 61326-1). While R22 refrigerant is retained for legacy compatibility, retrofit options using R404A or R507 are available for installations requiring updated refrigerant standards (per EU F-Gas Regulation No. 517/2014).

Software & Data Management

The circulator features a front-panel digital controller with real-time display of setpoint, actual bath temperature, pump status, and system fault codes. Optional RS485 Modbus RTU interface enables integration into centralized lab automation platforms (e.g., LabVantage, Thermo Fisher SampleManager) for remote parameter adjustment and event logging. Audit-trail-capable data export (CSV format) supports 21 CFR Part 11 compliance when paired with validated third-party SCADA software. All temperature readings are traceably calibrated against NIST-traceable reference probes (calibration certificate available upon request). Firmware updates are performed via USB port with version-controlled release notes aligned to ISO/IEC 17025 documentation practices.

Applications

• Controlled-temperature synthesis: exothermic Grignard additions, lithiation reactions, and hydrogenation protocols requiring sub-zero initiation followed by ramped heating
• Rotary evaporation optimization: maintaining condenser coil temperatures below dew point while controlling bath temperature for heat-sensitive compounds
• Material testing: thermal cycling of polymer samples per ASTM D696 and ISO 11359-2
• Pharmaceutical QC: dissolution apparatus temperature validation (USP ) and stability chamber support
• Biotechnology: temperature-controlled bioreactor jackets during fed-batch fermentation or enzyme kinetics assays
• Food science: rheological testing of emulsions and gels across freezing-to-boiling transitions

FAQ

What heat-transfer fluids are recommended for operation at −30 °C?
For sustained operation at −30 °C, a low-viscosity silicone oil (e.g., Wacker SE 1000) or 60/40 propylene glycol/water mixture is recommended. Ethylene glycol/water is not advised below −25 °C due to increased viscosity and potential pump cavitation.

Can this unit be integrated into a building management system (BMS)?
Yes—via optional Modbus RTU (RS485), the ZT-20-200-30H supports read-only monitoring of temperature, pump status, and alarms. Custom BMS integration requires protocol mapping by qualified controls engineers.

Is R22 refrigerant serviceable under current environmental regulations?
R22 is classified as an HCFC and is subject to phase-out timelines. The unit remains fully serviceable with reclaimed R22; however, conversion kits to R404A or R507 are available for new installations requiring future-proof refrigerant compliance.

What is the maximum allowable external loop resistance?
With 30 L/min flow and 1 bar pressure head, the system supports external circuits with total hydraulic resistance ≤ 8 m H₂O (equivalent to ~80 kPa), assuming 15 m of 16 mm ID stainless steel tubing and two standard quick-connect fittings.

Does the one-year warranty cover calibration verification?
The standard warranty includes functional verification against factory specifications. NIST-traceable calibration certification is available as a paid add-on service, delivered with documented uncertainty budgets per ISO/IEC 17025.