Julabo FT903 Immersion Cooling Circulator

Overview

The Julabo FT903 Immersion Cooling Circulator is a high-performance, dual-stage refrigerated circulator engineered for precise low-temperature control in demanding laboratory applications. Unlike conventional bath chillers or recirculating coolers, the FT903 employs an immersion-based architecture—its compact, stainless-steel cooling head is directly submerged into the process fluid, enabling rapid heat extraction via direct conduction and convection. This design eliminates thermal lag associated with external heat exchangers and significantly improves thermal response time and energy efficiency. The system utilizes a cascade refrigeration cycle combining R404A (first stage) and R23 (second stage), allowing stable operation from –100 °C to +30 °C without dry ice or liquid nitrogen. Its vertical footprint and integrated hose management support space-constrained setups, including glove boxes, cryogenic reaction vessels, and vacuum-jacketed reactors.

Key Features

• Dual-stage cascade refrigeration system delivering stable temperatures down to –100 °C with no consumables or cryogens required
• Stainless-steel (AISI 316) immersion probe optimized for chemical resistance and thermal conductivity; dimensions Ø56 mm × 140 mm (H)
• Precise temperature control with ±1 °C stability and 0.1 °C digital resolution on LED display
• Integrated PT100 external temperature sensor (200 mm × Ø6 mm, 1.5 m PTFE-insulated cable) included as standard for closed-loop feedback control
• Intelligent power modulation: cooling capacity dynamically adapts across the operating range (0.3 kW at 20 °C → 0.05 kW at –80 °C)
• Air-cooled condenser with low-noise fan design; ambient operating range 5–40 °C
• Compliant with IEC 61000-6-3 (EMC) and IEC 61010-1 (safety); CE-marked for laboratory use in EU and international markets

Sample Compatibility & Compliance

The FT903 is compatible with a broad spectrum of heat-transfer media—including silicone oils, ethylene glycol/water mixtures, and specialized low-temperature fluids—provided viscosity and flash point remain within ASME B31.5 and DIN 4754 safety guidelines. Its sealed immersion head prevents fluid ingress and supports operation under inert atmospheres (e.g., N₂ or Ar purged systems). From a regulatory standpoint, the unit meets essential requirements for GLP-compliant laboratories: temperature logging capability (via optional analog/digital interface), traceable calibration paths per ISO/IEC 17025, and mechanical design conforming to EN 61010-1 for protection against electric shock and mechanical hazards. While not inherently 21 CFR Part 11 compliant, its analog output (0–10 V / 4–20 mA) and RS232/RS485 interfaces enable integration into validated data acquisition systems supporting audit trails and electronic signatures.

Software & Data Management

The FT903 operates autonomously via its onboard controller but supports external supervision through industry-standard communication protocols. Optional Julabo WinTemp software enables remote monitoring, setpoint scheduling, and real-time graphing of temperature profiles over time. All operational parameters—including compressor status, refrigerant pressure diagnostics, and sensor fault flags—are accessible via Modbus RTU (RS485) or ASCII protocol (RS232), facilitating integration into SCADA or LIMS environments. For laboratories requiring long-term data integrity, third-party DAQ systems can record timestamps, setpoints, actual values, and alarm events with configurable sampling intervals (1 s to 60 min). The unit’s firmware supports firmware updates via USB and retains configuration settings during power loss.

Applications

• Cryogenic synthesis and low-temperature catalysis (e.g., Grignard reactions, lithiation, asymmetric hydrogenation)
• Calibration of thermocouples, RTDs, and infrared sensors across extended sub-ambient ranges
• Thermal conditioning of optical components, CCD detectors, and superconducting devices
• Controlled cooling of distillation columns, jacketed reactors, and crystallization vessels in pilot-scale process development
• Supporting ASTM D97 (pour point), ASTM D2500 (cloud point), and ISO 3016 testing protocols requiring precise sub-zero ramping
• Integration with Julabo heating circulators (e.g., HL series) to form full-range temperature control systems (–100 °C to +250 °C)

FAQ

Can the FT903 operate continuously at –100 °C?
Yes—when properly charged and maintained, the dual-stage cascade system is rated for continuous operation at –100 °C, provided ambient conditions remain within 5–40 °C and heat load does not exceed 0.05 kW.

Is the cooling head suitable for corrosive solvents like HF or fuming nitric acid?
No—the AISI 316 stainless-steel head offers excellent resistance to most organic solvents and mild acids, but is not compatible with hydrofluoric acid, hot concentrated HNO₃, or halogenated oxidizers. Consult Julabo’s chemical compatibility guide before exposure.

Does the FT903 include built-in temperature logging?
The base model does not feature internal memory for data storage, but real-time analog outputs and serial interfaces allow seamless connection to external loggers meeting GLP/GMP requirements.

What maintenance intervals are recommended?
Julabo recommends annual inspection of refrigerant charge, condenser coil cleaning, and verification of PT100 sensor accuracy per ISO/IEC 17025 procedures. Compressor oil analysis is advised every 24 months under continuous operation.

Can multiple FT903 units be daisy-chained for synchronized control?
Yes—using RS485 Modbus RTU, up to 32 units can share a single master controller for coordinated temperature sequencing in multi-zone experimental rigs.