Spectra Invent HX-AN1823 Automatic Acid Number Analyzer

Overview

The Spectra Invent HX-AN1823 Automatic Acid Number Analyzer is a dedicated potentiometric titration system engineered for precise and repeatable determination of acid number (AN) in insulating oils and industrial lubricants. It operates on the principle of non-aqueous potentiometric titration using standardized alcoholic potassium hydroxide (KOH) titrant, in accordance with internationally recognized test methods including ASTM D664, ISO 6618, and GB/T 258–2016 (replacing legacy GB/T 203.1 references). The instrument automates sample dissolution, titrant delivery, endpoint detection via pH-sensitive electrode pair, and stoichiometric calculation—eliminating operator bias and ensuring compliance with GLP and routine QC laboratory requirements in power generation, petrochemical refining, and turbine maintenance facilities.

Key Features

• Fully automated titration sequence: solvent addition, sample dissolution, titrant dosing, real-time potential monitoring, and automatic endpoint recognition based on first-derivative inflection point analysis
• Dual-electrode potentiometric detection system with temperature-compensated reference and indicator electrodes optimized for low-conductivity oil matrices
• Integrated magnetic stirring with variable speed control (100–800 rpm) to ensure homogeneous mixing without emulsion formation or electrode fouling
• Reagent management module with programmable titrant calibration, expiration tracking, and residual volume monitoring
• Robust architecture designed for continuous operation in industrial lab environments: IP20-rated enclosure, chemical-resistant fluid path components (PTFE, borosilicate glass, PEEK), and sealed reagent reservoirs
• Onboard data storage for ≥1,000 test records with timestamp, operator ID, method version, and raw potential vs. volume curves

Sample Compatibility & Compliance

The HX-AN1823 is validated for use with mineral-based transformer oils (e.g., naphthenic and paraffinic types), synthetic ester dielectrics, phosphate ester anti-wear fluids (e.g., Fire-Resistant Hydraulic Fluids), and steam turbine oils per IEC 60296 and ASTM D3487 specifications. It supports sample volumes from 10–50 g with optional gravimetric or volumetric introduction. All measurement protocols adhere to traceable metrological principles aligned with ISO/IEC 17025:2017 clause 7.7 (Sampling) and clause 7.8 (Technical Records). Method validation documentation—including precision (RSD ≤ 2.5% at AN = 0.1 mg KOH/g), spike recovery (98.2–101.7%), and linearity (r² ≥ 0.999 over 0.01–1.0 mg KOH/g)—is provided with each unit shipment.

Software & Data Management

The analyzer runs embedded firmware v3.2.x supporting dual-language UI (English/Chinese) and configurable audit trail logging compliant with FDA 21 CFR Part 11 requirements. Data export options include CSV, PDF report (with digital signature field), and direct integration via RS-232 or USB-C into LIMS platforms (e.g., LabWare, Thermo Fisher SampleManager). User access levels are enforced through password-protected roles (Operator, Supervisor, Administrator), with all critical actions—including method modification, calibration reset, and result deletion—recorded with immutable timestamps and user identifiers. Raw titration curves and intermediate calculations are retained for full traceability during internal audits or regulatory inspections.

Applications

• Condition monitoring of in-service transformer oil in substation asset management programs
• Quality release testing of new insulating oils prior to transformer filling
• Acid number trending in combined-cycle gas turbine lube oil systems per OEM maintenance intervals
• Research-grade oxidation stability assessment in accelerated aging studies (e.g., ASTM D2440)
• Regulatory compliance reporting for environmental discharge permits involving used industrial oils
• Root cause analysis of premature bearing failure linked to organic acid accumulation in circulating lubricants

FAQ

What standards does the HX-AN1823 comply with?
It supports ASTM D664 (potentiometric), ASTM D974 (color-indicator), ISO 6618, GB/T 258–2016, and IEC 62021-1 methodologies.
Can it analyze samples with high water content?
No—water interferes with non-aqueous titration; samples exceeding 500 ppm moisture must be pre-dried per ASTM D95 or ASTM D6304 prior to analysis.
Is method validation support included?
Yes—each instrument ships with a Certificate of Conformance, factory performance verification report, and a customizable IQ/OQ protocol template.
What maintenance is required for long-term accuracy?
Electrode cleaning every 20 tests, monthly titrant standardization against certified potassium hydrogen phthalate, and annual sensor calibration using NIST-traceable buffer solutions.
Does it support multi-sample batch processing?
Not natively—the HX-AN1823 processes one sample per cycle; however, sequential operation is enabled via programmable start delay and external autosampler compatibility (optional HX-AS12 add-on module).