JULABO AK40/AK80 High-Precision Temperature Calibration System

Overview

The JULABO AK40/AK80 High-Precision Temperature Calibration System is a traceable, metrology-grade thermal calibration platform engineered for laboratory and industrial applications requiring rigorous temperature validation. Built upon JULABO’s PRESTO-series closed-loop dynamic temperature control architecture, the system integrates a high-stability stainless steel calibration bath with an advanced ICC (Intelligent Cascade Control) temperature regulation module. It operates on the principle of forced-convection liquid circulation: thermally conditioned heat-transfer fluid—typically silicone oil or low-temperature synthetic fluid—is precisely regulated by the PRESTO controller, then delivered via a calibrated circulation pump through a submerged heat-exchange coil and bottom-distributed manifold. An overflow recirculation path ensures minimal vertical thermal gradient (<0.01 °C deviation across bath volume), eliminating thermal lag and enabling rapid equilibration—critical for ISO/IEC 17025-compliant calibration workflows. Designed for primary and secondary temperature standard comparison, the system supports reference thermometer immersion depths compliant with ASTM E74, ISO 5725, and EURAMET cg-18 guidelines.

Key Features

• Two model variants: AK40 (–40 °C to +250 °C) and AK80 (–80 °C to +250 °C), accommodating cryogenic and high-temperature calibration needs
• Stainless steel calibration bath with symmetrical geometry and optimized thermal mass distribution—engineered for superior uniformity and long-term stability
• ICC temperature control technology delivering ±0.002 °C short-term stability (over 30 min, at setpoint)
• Overflow circulation architecture ensuring ±0.01 °C spatial uniformity across full bath depth (384 mm) and diameter (118 mm)
• Intelligent variable-speed circulation pump with pressure-based or grade-based flow control—enabling optimization for sensor size, immersion depth, and medium viscosity
• Hermetically sealed bath design preventing volatile oil vapor emission; compatible with Class I cleanroom environments
• Standard M24×1.5 circulation ports; supplied with metal transfer tubing and adapter fittings for seamless integration with external reference sensors
• Optional insulated stainless steel lid or chemically inert PTFE lid for enhanced thermal retention and compatibility with aggressive media

Sample Compatibility & Compliance

The AK40/AK80 accommodates a wide range of temperature-sensitive devices including PRTs (Platinum Resistance Thermometers), RTDs, thermistors, liquid-in-glass thermometers, and digital temperature probes (e.g., Fluke, Hart, VTI). Its 7 L bath volume and 118 mm opening support simultaneous calibration of multiple sensors up to 300 mm in length. The system meets mechanical and thermal requirements for ISO/IEC 17025 accredited laboratories performing temperature calibration according to ILAC-G8 and EURAMET cg-18. Reference thermometers used with the system may be certified to DKD (Deutscher Kalibrierdienst) standards—traceable to PTB—or to CNAS-accredited certificates issued by the China National Institute of Metrology (NIM). All configurations comply with EU Machinery Directive 2006/42/EC and PED 2014/68/EU for pressurized fluid systems.

Software & Data Management

While the AK40/AK80 operates as a standalone hardware platform, it is fully compatible with third-party calibration software suites—including MET/CAL, DATACAL, and WinQbase—that support 21 CFR Part 11-compliant electronic records. The integrated temperature controller provides analog (0–10 V / 4–20 mA) and digital (RS485 Modbus RTU) outputs for real-time logging of bath setpoint, actual temperature, circulation pressure, and pump status. Audit trails, user access control, and electronic signature functionality are implemented at the host software level. JULABO provides calibration certificate templates aligned with ISO/IEC 17025 Annex A.3, supporting uncertainty budgeting per GUM (JCGM 100:2008).

Applications

• Primary calibration of reference thermometers in national metrology institutes and accredited calibration labs
• Validation of temperature sensors used in pharmaceutical manufacturing (e.g., autoclaves, lyophilizers, stability chambers) under FDA 21 CFR Part 11 and EU GMP Annex 15
• Thermal characterization of materials in polymer processing, aerospace composites testing, and battery R&D
• QC/QA temperature verification for food safety equipment (e.g., HACCP-compliant ovens, chillers, retorts)
• Research-grade thermophysical property measurement where thermal homogeneity directly impacts data fidelity (e.g., DSC baseline validation, thermal conductivity studies)

FAQ

What reference fluids are recommended for the AK40 and AK80 models?

For AK40 (–40 °C to +250 °C), use high-stability silicone oils (e.g., JULABO SIL 200 series). For AK80 (–80 °C to +250 °C), low-pour-point synthetic heat-transfer fluids (e.g., JULABO F25 or similar) are required. Fluid selection must consider viscosity, flash point, and thermal degradation limits.
Is the system suitable for GLP or GMP-regulated environments?

Yes—the AK40/AK80’s mechanical design, traceable temperature control, and compatibility with 21 CFR Part 11-compliant software enable full audit readiness. Documentation packages include IQ/OQ protocols and uncertainty budgets per ISO/IEC 17025.
Can the bath be customized for non-standard sensor geometries?

Yes—JULABO offers OEM bath modifications including extended depth, custom port layouts, and immersion well inserts to accommodate large-format or multi-sensor fixtures.
Does the system include a certified reference thermometer?

No—the AK40/AK80 is supplied without a certified reference sensor. Customers select and procure DKD- or NIM-certified PRTs separately based on required uncertainty class (e.g., Class A or AA per IEC 60751).
What maintenance is required to sustain metrological performance?

Annual recalibration of the internal platinum resistance sensor and verification of circulation pump flow rate and pressure response are recommended. Bath fluid should be replaced per manufacturer specifications (typically every 12–24 months depending on thermal cycling frequency and operating range).