Julabo F25-HL Advanced Heating and Cooling Circulating Bath

Overview

The Julabo F25-HL is a high-precision, air-cooled heating and cooling circulating bath engineered for demanding laboratory applications requiring stable thermal control across an exceptionally wide operating range (−28 °C to +200 °C). Designed around Julabo’s proprietary Intelligent Control Circuit (ICC) and Thermal Control Function (TCF) algorithms, the F25-HL delivers ±0.01 °C temperature stability in the bath reservoir—critical for reproducible calibration, kinetic studies, and external system conditioning. Its dual-mode circulation architecture supports both internal bath homogenization and precise external temperature regulation of peripheral instruments such as viscometers, refractometers, spectrophotometers, and jacketed reactors. The unit employs a single-stage R134a refrigeration system combined with a high-efficiency 2 kW resistive heater and a Smartpump™ variable-pressure circulation system capable of dynamically adapting flow pressure (0.4–0.7 bar) and suction (0.2–0.4 bar) to compensate for changes in fluid viscosity or line resistance—ensuring consistent thermal transfer under variable load conditions.

Key Features

• VFD/LCD dual-display interface with white backlight and IP65-rated waterproof keypad for intuitive parameter entry, alarm threshold setting, and real-time monitoring of setpoint, actual bath temperature, external sensor input, and system status.
• ICC self-tuning algorithm automatically optimizes PID parameters during initial commissioning and adapts to changing thermal loads—reducing overshoot and shortening stabilization time.
• ATC3 three-point temperature calibration function enables traceable, user-performed verification and adjustment using certified Pt100 reference probes—supporting ISO/IEC 17025-compliant lab practices.
• Integrated external Pt100 sensor port allows direct measurement and closed-loop control of temperature at the point of use (e.g., reactor jacket inlet/outlet), decoupling control accuracy from bath-to-device thermal lag.
• Smartpump™ technology modulates motor power in real time to maintain target flow rate and pressure across varying fluid viscosities—eliminating manual pump adjustments when switching between water, silicone oil, or glycol-based heat transfer fluids.
• Comprehensive safety architecture includes low-bath-level detection, hardware-based overtemperature cut-off (mechanical rotary dial adjustable up to +210 °C), refrigerant leak monitoring, and automatic shutdown on compressor overload or sensor fault.
• Standard RS232 interface enables bidirectional communication with LabVIEW, MATLAB, or custom SCADA systems; optional RS485 or Profibus modules support integration into centralized facility control networks compliant with ISA-88/ISA-95 frameworks.

Sample Compatibility & Compliance

The F25-HL accommodates standard heat transfer media including deionized water, aqueous glycol mixtures (up to 50 vol%), and silicone oils (cSt ≤ 1000). Its stainless-steel bath chamber and wetted components meet FDA-relevant material compatibility standards (ASTM F2129 for corrosion resistance). The unit conforms to IEC 61010-1 (Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use) and EN 61326-1 (EMC requirements for laboratory equipment). Its Classification III (FL) designation indicates suitability for use with flammable liquids under controlled ventilation per DIN EN 14520. All firmware and control logic are designed to support audit-ready operation in GLP and GMP environments, including configurable event logging and optional 21 CFR Part 11-compliant electronic signature modules (via third-party software integration).

Software & Data Management

While the F25-HL operates autonomously via its front-panel interface, its RS232 port enables full remote control—including setpoint ramping, program execution, real-time data streaming (temperature, pump status, alarms), and firmware updates—using Julabo’s free WinLab software or industry-standard protocols (Modbus RTU over RS232). The embedded 6×60-step programmable controller supports complex multi-segment temperature profiles with dwell times, ramps, and hold conditions—ideal for accelerated stability testing (ICH Q1A) or polymer curing cycles. Event logs record timestamps for all critical events (e.g., low-level alerts, overtemperature trips, power interruptions) with retention sufficient for 30 days of continuous operation. Optional analog I/O modules (0–10 V or 4–20 mA) permit analog interfacing with PLCs or DCS systems for cascade control architectures.

Applications

• Calibration of temperature-sensitive analytical instruments (e.g., HPLC column ovens, DSC reference cells, FTIR sample compartments).
• Active temperature control of jacketed glass reactors during exothermic/endothermic synthesis, enabling precise reaction enthalpy profiling.
• Viscosity measurement support for rotational rheometers and capillary viscometers requiring stable thermal boundary conditions per ASTM D445 and ISO 3104.
• Refractometer and polarimeter thermal equilibration per USP and Ph. Eur. 2.2.47 specifications.
• Material testing environments for thermal expansion coefficient determination (ASTM E228) and heat capacity measurements (ASTM E1269).
• Preconditioning of samples and standards prior to mechanical, electrical, or optical characterization in metrology labs.

FAQ

What external temperature sensors are compatible with the F25-HL?
The unit accepts standard 2-, 3-, or 4-wire Pt100 sensors (DIN EN 60751 Class A or B) via its dedicated analog input. Third-party sensors must comply with IEC 60751 tolerance curves and operate within −50 °C to +250 °C.
Can the F25-HL be used with silicone oil at 200 °C without degradation?
Yes—when operated within its specified 4.5 L fill volume and with periodic maintenance (filter cleaning every 6 months), the F25-HL maintains thermal stability and pump integrity with methylphenyl silicone oils meeting Dow Corning 200 Fluid specifications.
Is the RS232 interface galvanically isolated?
No—the RS232 port is not optically isolated; for electrically noisy environments or long cable runs (>2 m), Julabo recommends using an externally powered RS232-to-USB isolator or upgrading to the optional RS485 module.
Does the ATC3 calibration require external hardware?
Yes—ATC3 requires a NIST-traceable reference thermometer (e.g., Fluke 1523 or equivalent) and three stable temperature points spanning the operational range; procedure details are documented in the user manual’s Calibration chapter.
How often should the condenser grille be cleaned?
In typical lab environments (23 °C, 50% RH), Julabo recommends inspecting and cleaning the removable condenser grille every 3 months using compressed air or a soft brush; frequency increases in dusty or high-humidity settings.