Hanuo HN-300A Precision Standard Oil Bath Calibrator

Overview

The Hanuo HN-300A Precision Standard Oil Bath Calibrator is a high-stability, laboratory-grade temperature reference source engineered for metrological traceability in thermal calibration workflows. Operating on the principle of convective heat transfer within a thermally homogeneous silicone oil medium, the unit maintains a precisely controlled isothermal environment across its vertical working zone—enabling accurate immersion-based calibration of primary and secondary temperature standards. Designed to meet the stringent requirements of national metrology institutes and accredited calibration laboratories, the HN-300A serves as a primary reference bath for calibrating liquid-in-glass thermometers (including Class I and II mercury-in-glass and Beckmann thermometers), industrial platinum resistance thermometers (PRTs), and standard copper-constantan thermocouples per ISO/IEC 17025, JJG 50–2019 (Chinese National Calibration Specification for Liquid-in-Glass Thermometers), and ASTM E77. Its all-stainless-steel construction ensures long-term corrosion resistance and thermal inertia stability, while the deep immersion geometry (Ø150 mm × 480 mm) supports full immersion of standard thermometers up to 450 mm in length—critical for minimizing stem-exposure errors in fixed-point or comparison calibrations.

Key Features

• High-precision PID temperature controller with adaptive tuning, delivering ≤0.01 °C short-term stability over 30-minute intervals and ±0.01 °C axial/radial uniformity across the defined working zone.
• Robust stainless-steel tank and internal circulation system optimized for methyl silicone oil (flash point >300 °C), ensuring chemical inertness, low volatility, and minimal oxidation at sustained 300 °C operation.
• Internal recirculation architecture eliminates external plumbing, reducing thermal lag and contamination risk while maintaining laminar flow profiles for consistent heat distribution.
• Thermally insulated enclosure with dual-layer vacuum-jacketed design minimizes ambient heat exchange, enabling stable operation in environments up to 35 °C ambient temperature.
• Integrated safety interlocks include overtemperature cutoff (settable), dry-run protection, and ground-fault circuit interruption (GFCI) compliant with IEC 61000-6-3 EMC standards.

Sample Compatibility & Compliance

The HN-300A accommodates a broad range of temperature-sensitive artifacts requiring full-immersion calibration: standard mercury-in-glass thermometers (up to 450 mm), SPRTs and PRTs with sheath diameters ≤12 mm, thermocouple reference junctions, and digital thermometer probes. It complies with key regulatory and quality frameworks including ISO/IEC 17025:2017 Clause 6.4.7 (environmental monitoring), JJG 50–2019, JJG 229–2010 (industrial platinum resistance thermometers), and JJG 368–2003 (copper-constantan thermocouples). While not intrinsically compliant with FDA 21 CFR Part 11, its stable output and documented thermal performance support integration into GLP/GMP validation protocols when paired with qualified data loggers and audit-trail-enabled software.

Software & Data Management

The HN-300A operates as a standalone analog-controlled instrument; no embedded software or digital interface is provided. However, it is fully compatible with third-party calibration management systems via analog voltage output (0–10 V DC proportional to setpoint deviation) and RS-485 Modbus RTU optional module (available upon request). Users may integrate the bath into automated calibration sequences using platforms such as Fluke Metrology Software, MET/TEMP II, or custom LabVIEW applications. All calibration records—including bath setpoint, measured sensor readings, soak duration, and environmental conditions—must be manually logged or captured via external DAQ systems to satisfy ISO/IEC 17025 documentation requirements.

Applications

• Primary calibration of reference thermometers in metrology labs and national standards bodies.
• Verification and periodic requalification of industrial temperature sensors prior to field deployment.
• Thermal characterization of materials requiring stable high-temperature exposure (e.g., polymer melt viscosity pre-conditioning, thermal aging studies).
• Supporting fixed-point cell realization (e.g., Zn, Al, Ag) by providing stable intermediate temperature plateaus during interpolation.
• Providing traceable thermal sources for R&D in aerospace, semiconductor processing, and pharmaceutical manufacturing where process temperature uncertainty budgets demand sub-0.02 °C contributions from the reference source.

FAQ

What temperature media are recommended for the HN-300A?
Methyl silicone oil (e.g., Dow Corning 200 Fluid, viscosity grade 100–350 cSt) is specified for operation up to 300 °C. Water is incompatible above 95 °C and must not be used.
Is external circulation supported?
No—the HN-300A features internal recirculation only. External pump interfaces are not available on this model.
Can the unit be used for cooling applications?
No—it is a heating-only system. For combined heating/cooling capability, consider the HN-300C variant (not covered here).
What is the recommended maintenance interval?
Oil level and clarity should be verified before each calibration session; full oil replacement is advised every 12 months under continuous use or after 2000 hours of operation at >250 °C.
Does the HN-300A include a calibration certificate?
No—certification is provided separately upon request and traceable to NIM (National Institute of Metrology, China) or equivalent NMIs; fees and lead time apply.