ATAGO CM-ISα Battery Electrolyte In-Line Refractometer
| Brand | ATAGO |
|---|---|
| Origin | Japan |
| Model | CM-ISα |
| Product Type | In-Line Refractometer |
| Display | Digital |
| Measurement Range | Refractive Index (nD): 1.32000–1.49100 |
| Brix | 0.00–80.0% |
| Accuracy | ±0.0002 (nD), ±0.1% (Brix) |
Overview
The ATAGO CM-ISα Battery Electrolyte In-Line Refractometer is an industrial-grade, process-integrated optical instrument engineered for continuous, real-time monitoring of sulfuric acid (H₂SO₄) concentration in lead-acid battery electrolyte production lines. Based on the principle of critical-angle refractometry, the CM-ISα measures the refractive index (nD) of flowing liquid media—directly correlating to solute concentration via calibrated polynomial functions. Unlike laboratory-based benchtop refractometers or offline titration methods, the CM-ISα operates in situ within pressurized, temperature-controlled process piping (typically stainless steel 316L), delivering stable, high-reproducibility readings under dynamic flow conditions. Its optical sensing head employs a sapphire prism interface and temperature-compensated LED light source, ensuring minimal drift across ambient operating temperatures from 0 °C to 60 °C. Designed specifically for battery manufacturing environments, it supports closed-loop feedback integration with PLCs and DCS systems to enable automated dilution control during acid filling and formation processes.
Key Features
- Explosion-proof construction compliant with ATEX Directive 2014/34/EU (Category 2G, Zone 1, II 2G Ex db IIB T4 Gb) and IECEx certification (Ex db IIB T4 Gb), suitable for hazardous areas where flammable vapors may be present
- Integrated Pt100 RTD sensor for real-time temperature compensation (0–60 °C range), eliminating manual correction and ensuring traceable nD values per ISO 21748 and ASTM D1218
- Digital output via 4–20 mA analog signal (HART optional) and RS-485 Modbus RTU protocol for seamless integration into SCADA and MES platforms
- IP67-rated stainless steel housing with sanitary tri-clamp (DIN 11851) or threaded (NPT/G) process connections for hygienic and corrosion-resistant installation
- Zero-point stability maintained over 6 months without recalibration under normal operating conditions, verified per ATAGO’s internal QA-12 validation protocol
- Self-diagnostic firmware with alarm outputs for flow interruption, prism fouling detection, and signal loss—supporting predictive maintenance planning
Sample Compatibility & Compliance
The CM-ISα is validated for use with aqueous sulfuric acid solutions ranging from ~5% to 40% w/w H₂SO₄—covering all standard battery electrolyte formulations used in SLI (starting-lighting-ignition), VRLA (valve-regulated lead-acid), and flooded deep-cycle applications. It is not intended for undiluted 98% acid or organic solvent mixtures. The instrument conforms to ISO 21748:2017 (Guidance for the evaluation of measurement uncertainty in refractometric analysis) and supports compliance with GMP Annex 11 (Computerised Systems) and FDA 21 CFR Part 11 when deployed with audit-trail-enabled data logging software. All calibration certificates are traceable to NMIJ (National Metrology Institute of Japan) reference standards.
Software & Data Management
The CM-ISα interfaces with ATAGO’s proprietary PC-based configuration tool (RefractoLink™ v3.2), enabling user-defined Brix-to-H₂SO₄ conversion curves based on empirical density tables (e.g., DIN 51757, IEC 60896-21). Historical measurement data—including nD, Brix, temperature, and timestamped alarms—can be exported in CSV or XML format for statistical process control (SPC) analysis. When integrated with enterprise-level LIMS or SAP QM modules, the system supports electronic batch records (EBR) and full 21 CFR Part 11-compliant audit trails, including operator login, parameter changes, and calibration events.
Applications
- Real-time concentration control during acid dilution staging in multi-concentration battery manufacturing lines
- In-line verification of electrolyte strength post-forming and pre-filling to ensure adherence to HG/T 2692–2007 (Industrial Sulfuric Acid for Lead-Acid Batteries)
- Reduction of line stoppage time during product changeovers—from up to 40 minutes (lab-based titration) to under 90 seconds with closed-loop PID adjustment
- Monitoring of electrolyte consistency across large-format traction battery cells to prevent capacity imbalance and premature sulfation
- Supporting Six Sigma initiatives by reducing sigma shift due to manual sampling variability and human transcription error
FAQ
Is the CM-ISα suitable for measuring concentrated sulfuric acid (>60% w/w)?
No. The CM-ISα is calibrated and validated exclusively for aqueous H₂SO₄ solutions between 5% and 40% w/w. Exposure to >50% acid may cause prism etching and irreversible optical degradation.
Can the device be installed vertically or only horizontally?
It supports both orientations; however, horizontal mounting with minimum flow velocity ≥0.3 m/s is recommended to prevent air entrapment and ensure laminar flow across the sensing prism.
Does the CM-ISα require periodic cleaning or maintenance?
Yes—prism inspection and gentle cleaning with deionized water and lint-free wipes are recommended every 2–4 weeks depending on particulate load. No consumables or reagents are required.
How is calibration performed in a production environment?
Field calibration uses certified NIST-traceable sucrose or sulfuric acid reference standards (e.g., 10.00±0.01% H₂SO₄). Two-point calibration (zero and span) is supported via RefractoLink™; full validation per ISO/IEC 17025 is advised annually.
What certifications does the CM-ISα hold for use in North American facilities?
It carries UL/cULus Listing for Class I, Division 1, Groups B, C, D; and CSA Group certification for hazardous location use in Canada and the U.S., meeting NEC Article 500 requirements.
