Brookfield SD90738 Portable Chlorine Dioxide Analyzer

Overview

The Brookfield SD90738 Portable Chlorine Dioxide Analyzer is a field-deployable, electrochemical sensor-based instrument engineered for precise, real-time quantification of aqueous chlorine dioxide (ClO₂) concentration in drinking water, wastewater effluent, swimming pool circulation systems, and industrial process streams. Unlike colorimetric or photometric methods—which rely on reagent-induced chromogenic reactions and optical density interpretation—the SD90738 employs a selective amperometric electrochemical transducer calibrated to respond specifically to ClO₂ redox activity at a defined working electrode potential. This principle eliminates interferences from residual free chlorine, chloramines, or organic oxidants that commonly compromise spectrophotometric accuracy. The device operates under ambient temperature and pressure conditions, requires no external gas supply or carrier stream, and delivers stable output within 60 seconds of sample introduction. Its design adheres to the fundamental metrological requirements outlined in ISO 7888 (Water quality — Determination of chlorine dioxide, free chlorine and combined chlorine) and aligns with measurement traceability frameworks referenced in US EPA Method 327.0 and ASTM D6503.

Key Features

• Integrated amperometric ClO₂ sensor with Pt/Ag/AgCl reference system and proprietary membrane formulation for enhanced selectivity against Cl₂, O₃, and NO₂⁻
• Microprocessor-controlled signal conditioning circuitry featuring automatic temperature compensation (0–40 °C) and dual-point auto-calibration capability
• Backlit 128×64 dot-matrix LCD display with intuitive touch-sensitive keypad navigation and on-screen unit toggle (mg/L, ppm, μmol/L)
• Non-linear curve fitting algorithm supporting up to 10 user-defined calibration points; pre-loaded with NIST-traceable ClO₂ response curves per GB/T 5750.11–2006 Annex A
• Rugged IP65-rated ABS housing with integrated sample chamber, ergonomic grip, and replaceable sensor cartridge (typical service life: ≥12 months under routine use)
• Low-power operation via internal rechargeable Li-ion battery (≥10 h continuous use) or optional AC adapter (100–240 VAC, 50/60 Hz)

Sample Compatibility & Compliance

The SD90738 is validated for direct analysis of clarified, non-turbid aqueous matrices with total suspended solids (TSS) < 10 mg/L and pH 5.0–8.5. It is not intended for undiluted seawater, highly acidic leachates (pH 10 mg/L hydrogen peroxide or reducing sulfides. All factory calibrations are performed using certified ClO₂ standard solutions traceable to NIM (National Institute of Metrology, China) and cross-verified against gravimetrically prepared KIO₃-based reference materials. Device firmware and calibration records support audit-ready documentation per GLP and ISO/IEC 17025 requirements. Data export complies with FDA 21 CFR Part 11 when paired with optional PC interface software (USB-C connection, .csv/.xlsx output).

Software & Data Management

The analyzer stores up to 500 measurement records with timestamp, temperature, calibration ID, and operator code. Internal memory supports chronological sorting, batch recall, and statistical summary (mean, SD, CV%). Optional PC connectivity enables synchronization with Brookfield AquaTrack™ Desktop Suite v3.2—providing automated report generation (PDF/Excel), trend charting, and electronic signature workflows compliant with 21 CFR Part 11 Annex 11. Calibration logs include sensor drift diagnostics, zero-offset verification history, and pass/fail status flags aligned with ISO 17025 clause 7.7.1.

Applications

• Verification of ClO₂ dosing efficacy in municipal drinking water treatment plants (post-contact tank sampling)
• Monitoring disinfectant residuals in recirculating swimming pool and spa systems per CDC Model Aquatic Health Code (MAHC) Section 6.003
• Process control of ClO₂ injection in pulp & paper bleaching lines and food processing CIP rinse validation
• Field screening of emergency water supplies following natural disasters (FEMA P-361 guidance)
• Educational laboratory instruction for environmental chemistry courses covering oxidation-reduction titrimetry and sensor electrochemistry

FAQ

What sample pretreatment is required prior to measurement?
No filtration or acidification is needed for clear potable water. For turbid or high-organic-content samples (e.g., wastewater effluent), centrifugation (3,000 rpm, 5 min) or 0.45 µm membrane filtration is recommended to prevent sensor fouling.
Can the SD90738 measure both free chlorine and chlorine dioxide simultaneously?
No. The SD90738 is dedicated exclusively to ClO₂ detection. Free chlorine must be measured separately using a compatible amperometric sensor (e.g., SD90762 model) due to distinct redox potentials and membrane selectivity requirements.
How often does the sensor require recalibration?
Daily zero-point verification is advised for critical applications; full two-point calibration (0 and 1.0 mg/L ClO₂ standards) is required every 8 hours of cumulative operation or before each new sampling campaign.
Is the instrument suitable for regulatory reporting under EPA or EU Drinking Water Directive?
Yes—when operated per manufacturer’s SOP and maintained with documented calibration history, data generated meets the performance criteria specified in EPA Method 327.0 and EU Council Directive 98/83/EC Annex II for ClO₂ monitoring.
What is the warranty coverage and service support structure?
Brookfield provides a 24-month limited warranty covering parts and labor for defects in materials or workmanship. Extended calibration certification and on-site technical support are available through authorized service centers in North America, EMEA, and APAC regions.