Julabo SL-6 High-Temperature Circulating Bath

Overview

The Julabo SL-6 High-Temperature Circulating Bath is a precision-engineered thermal management system designed for demanding laboratory and industrial applications requiring stable, controllable heating across an extended temperature range. Operating on the principle of forced convection via an integrated circulation pump, the SL-6 delivers uniform thermal energy to samples immersed directly in the bath or to external devices—such as jacketed reactors, viscometers, chromatography columns, polarimeters, electrophoresis units, and spectrophotometers—via closed-loop external circulation. Its stainless-steel construction, DIN 12876-1 Class III (FL) certification for use with flammable heat transfer fluids (e.g., silicone oils), and robust thermal architecture make it suitable for continuous operation at temperatures up to +250 °C. Unlike basic immersion heaters, the SL-6 integrates advanced control logic—including ICC (Intelligent Control Circuitry) and TCF (Temperature Control Framework)—to maintain ±0.01 °C stability under dynamic load conditions, even when fluid viscosity changes due to temperature drift or external heat exchange.

Key Features

• ICC Intelligent Temperature Control Algorithm: Eliminates need for manual self-tuning; achieves high reproducibility without user intervention.
• VFD-LCD Dual Display: Simultaneously shows setpoint, internal bath temperature, and external sensor reading (via optional or integrated PT100); displays real-time pump power %, heating status, liquid level, voltage, and pressure output.
• ATC3 Three-Point User Calibration: Enables traceable field calibration at three user-defined temperatures (e.g., 25 °C, 100 °C, 200 °C), supporting ISO/IEC 17025-compliant lab practices.
• Smart Pump Technology: Automatically adjusts motor output to compensate for viscosity-induced flow resistance—critical when using high-boiling-point oils across wide temperature spans.
• Dual Safety Architecture: Independent overtemperature cut-off (adjustable via dedicated knob) plus programmable upper/lower temperature limits with audible/visual alarm and automatic shutdown.
• Low-Level Pre-Alarm System: Triggers warning before critical fluid level is reached—ensuring uninterrupted operation while prompting timely refilling.
• TCF Dynamic Control Framework: Supports configurable interlock logic between internal and external temperatures, enabling complex ramp-hold-cool sequences and differential thermal constraints.
• Standard RS232/RS485 Interfaces: Enable remote monitoring, logging, and integration into centralized Lab Information Management Systems (LIMS) or SCADA platforms; Profibus-DP option available for factory automation environments.
• Modular Expansion Support: Optional analog I/O module for PLC integration, electromagnetic valve interface for auxiliary cooling/heating actuation, and insulated bath lid with cooling coil for ambient-temperature stabilization.

Sample Compatibility & Compliance

The SL-6 accommodates direct immersion of small-to-medium samples (up to 6 L bath volume) and supports external temperature regulation of process equipment via flexible tubing (8 mm and 12 mm ID, included). Its Class III (FL) certification per DIN 12876-1 confirms suitability for use with flammable heat transfer media—including silicone oils, glycols, and specialty synthetic fluids—under controlled laboratory conditions. The unit complies with EN 61000-6-3 (EMC emission) and EN 61000-6-2 (immunity), and meets essential safety requirements of the EU Machinery Directive 2006/42/EC. For regulated environments, its programmable audit trail (via external software), configurable alarm logging, and deterministic response to safety events support alignment with GLP and GMP documentation expectations—particularly where thermal validation of analytical instrumentation or material testing protocols is required.

Software & Data Management

While the SL-6 operates autonomously via front-panel controls, its embedded serial interfaces allow full bidirectional communication with third-party software tools. Julabo’s proprietary WinWeld software (Windows-based) enables real-time graphing, multi-channel data export (CSV/TXT), event-triggered logging, and execution of up to six independent temperature programs (each with up to 60 segments). When connected to a validated LIMS or electronic lab notebook (ELN), the device can feed timestamped temperature readings with instrument ID and firmware version—facilitating 21 CFR Part 11–compliant record retention when paired with appropriate access controls and electronic signature workflows. All configuration parameters—including calibration offsets, alarm thresholds, and pump profiles—are stored non-volatilely and survive power cycling.

Applications

• Calibration and verification of temperature-sensitive analytical instruments (e.g., HPLC column ovens, rotational viscometers, DSC reference cells).
• Thermal conditioning of polymer melts, elastomers, and composite resins prior to rheological or mechanical testing.
• Stabilization of optical components (e.g., laser diodes, interferometer stages) requiring sub-0.02 °C thermal homogeneity.
• Controlled heating of jacketed glass reactors during exothermic synthesis or catalytic studies.
• Pre-conditioning of biological samples (e.g., enzyme assays, protein denaturation kinetics) within defined thermal windows.
• Support of ASTM D445 (kinematic viscosity), ISO 3104, and USP environmental stability testing protocols.

FAQ

Can the SL-6 be used with silicone oil? Why is Class III (FL) certification important?
Yes—the SL-6 is explicitly certified to DIN 12876-1 Class III (FL), permitting safe operation with flammable heat transfer fluids such as dimethyl silicone oil. This classification mandates enhanced fire-resistant housing, sealed electronics, and vapor-tight connections.
Does the SL-6 support cooling functions?
No—the SL-6 is a heating-only circulator. However, its integrated cooling coil (standard on all models) facilitates passive heat dissipation near ambient, extending low-temperature usability down to +5 °C without external chillers.
How does ATC3 calibration differ from standard offset adjustment?
ATC3 performs linear interpolation across three user-measured points, correcting for sensor nonlinearity across the operational span—unlike single-point offset, which assumes constant error.
Is external PT100 connectivity mandatory for external system control?
No—it is optional but recommended for accurate feedback control of remote loads; the SL-6 will default to internal bath sensing if no external probe is connected.
What maintenance intervals are recommended for long-term reliability?
Julabo recommends annual verification of temperature accuracy against a NIST-traceable reference thermometer and inspection of pump seals and fluid condition—especially after prolonged operation above 180 °C.