Julabo CF31 Compact Heating and Cooling Circulating Bath

Overview

The Julabo CF31 Compact Heating and Cooling Circulating Bath is an engineered thermal management system designed for precision temperature control in laboratory and analytical applications requiring both heating and refrigeration capabilities within a minimal footprint. Based on closed-loop liquid circulation thermodynamics, the CF31 employs a high-efficiency single-stage compressor (R134a refrigerant) combined with a 2 kW resistive heating element to achieve stable operation across an extended temperature range of −30 °C to +200 °C. Its compact form factor—measuring only 24 × 46 × 40 cm—enables seamless integration into fume hoods, glove boxes, or densely configured instrument racks without compromising thermal performance. The unit conforms to DIN 12876-1 Class III (FL) safety requirements for flammable liquid environments, featuring no side exhaust vents, flame-retardant housing materials, and integrated leak detection logic. All wetted components—including the bath chamber, pump head, and internal piping—are constructed from electropolished stainless steel (AISI 316) and chemically resistant PPSU polymers, ensuring long-term compatibility with water, silicone oils, glycol/water mixtures, and other common heat-transfer fluids.

Key Features

• Intelligent ICC (Intelligent Cascade Control) algorithm enabling rapid thermal response while maintaining ±0.02 °C stability at setpoint—validated per ISO/IEC 17025 traceable calibration protocols
• VFD + LCD dual-display interface with tactile rotary encoder and splash-proof membrane keypad for intuitive parameter entry and real-time monitoring
• Programmable temperature ramping with up to six independent profiles, each supporting 60 time–temperature steps for automated thermal cycling (e.g., polymer curing, enzyme kinetics)
• Adjustable electronic pressure-controlled circulation pump (22–26 L/min, 0.4–0.7 bar max) with M16×1 external port and included 8 mm / 12 mm barbed fittings
• Integrated Pt100 input channel for direct external system temperature feedback—supports remote sensor placement up to 50 m with 4-wire compensation
• Three-point temperature calibration routine (−10 °C, 25 °C, 100 °C) compliant with ASTM E1137 and ISO 17025 documentation requirements
• Comprehensive safety architecture: low-fluid-level cutoff, overtemperature shutdown (user-configurable threshold), motor overload protection, and refrigerant pressure monitoring
• RS232 and RS485 serial interfaces support SCPI command sets; optional Profibus-DP module enables integration into PLC-based lab automation systems

Sample Compatibility & Compliance

The CF31 accommodates small-volume samples (≤3.5 L bath capacity) and is routinely deployed for jacketed reactor temperature control, viscometer bath immersion, spectrophotometer cell compartment conditioning, and calorimeter reference baths. Its Class III (FL) certification under DIN 12876-1 permits safe operation with flammable solvents such as acetone, ethanol, or hexane—provided ambient ventilation meets EN 14175 standards. The unit complies with electromagnetic compatibility (EMC) per EN 61326-1 and electrical safety per EN 61010-1. All firmware logs include timestamped audit trails for GLP/GMP environments; optional 21 CFR Part 11-compliant software packages provide electronic signature support and user access controls.

Software & Data Management

Julabo’s optional WinTherm software provides full remote operation via USB-to-RS232 adapter or Ethernet gateway. Users can define multi-step temperature programs, export CSV-formatted time-series data (including bath temperature, external sensor reading, pump status, and error codes), and generate PDF calibration reports. Internal memory retains ≥10,000 data points with millisecond timestamp resolution. For networked labs, Modbus TCP integration allows centralized monitoring through LabVIEW, MATLAB, or custom SCADA platforms. Firmware updates are delivered via signed .hex files verified against SHA-256 checksums to ensure integrity.

Applications

• Precise thermal conditioning of HPLC column ovens and detector flow cells
• Stabilization of laser diodes and photodetectors requiring sub-0.05 °C drift control
• Calibration of thermocouples, RTDs, and infrared thermometers per ISO/IEC 17025
• Accelerated aging studies in material science (e.g., epoxy cure profiling, elastomer relaxation tests)
• Controlled cooling/heating of microfluidic chips during PCR or immunoassay development
• Temperature-dependent viscosity measurements using rotational rheometers with external jacketing

FAQ

What is the maximum recommended working fluid temperature for continuous operation?
Continuous operation at +200 °C requires silicone oil (e.g., Dow Corning 200 Fluid, 50 cSt) and strict adherence to fluid change intervals (every 6 months or 1,000 operating hours). Water-based fluids are limited to ≤95 °C.
Can the CF31 be used for external circulation only—without filling the internal bath?
No. The unit requires minimum fill level (≥2.8 L) to ensure proper refrigerant coil submersion and pump priming. Dry-run operation will trigger immediate shutdown.
Is the RS485 interface galvanically isolated?
Yes—opto-isolated RS485 circuitry ensures noise immunity in electrically noisy industrial lab environments and prevents ground loop interference.
How is traceability maintained for temperature calibration?
Each unit ships with a factory-issued calibration certificate referencing NIST-traceable standards; users may perform field verification using certified Pt100 probes and document deviations in accordance with ISO/IEC 17025 Clause 6.5.
Does the CF31 support PID auto-tuning for custom external loads?
No—PID parameters are pre-optimized for Julabo’s standard bath geometry and thermal mass. External load tuning must be performed manually via ICC gain adjustment in expert mode.