COD Digester Model 5-0102

Overview

The COD Digester Model 5-0102 is a precision-controlled thermal digestion unit engineered for standardized chemical oxygen demand (COD) determination in accordance with ISO 6060, ASTM D1252, and EPA Method 410.1. It operates on the principle of closed-vessel, acid-mediated oxidation under controlled thermal conditions—typically using potassium dichromate (K₂Cr₂O₇) in concentrated sulfuric acid (H₂SO₄) at elevated temperatures—to convert organic matter in aqueous samples into CO₂ and H₂O. The digester provides thermally stable, reproducible heating profiles essential for quantitative back-titration or spectrophotometric quantification of residual oxidant. Designed for integration with benchtop photometric analyzers—including the CODPlus COD Analyzer, SMART2 Multi-parameter Water Analyzer, and SMART Spectro Spectrophotometer—the unit supports both low-range (0–150 mg/L) and high-range (up to 15,000 mg/L) COD assays via compatible reagent kits.

Key Features

• Microprocessor-driven digital temperature control with real-time PID feedback for ±0.1 °C stability and uniformity at 100 °C—critical for inter-laboratory method reproducibility.
• Dual-capacity block design accommodating either 12 or 24 standard 16 mm borosilicate digestion tubes, enabling flexible batch processing without cross-contamination risk.
• Programmable timer (0–999 minutes) with audible end-of-cycle alert and automatic power cutoff upon reaching user-defined duration.
• Integrated over-temperature safety shutdown at 212 °C—exceeding maximum operational setpoints while preserving heater integrity and sample containment.
• Compact footprint (≤300 × 250 × 180 mm) optimized for limited bench space in accredited environmental testing labs and municipal wastewater quality control facilities.
• CE-marked construction compliant with IEC 61010-1 for electrical safety in laboratory environments; no moving parts or consumable heating elements beyond the metal block assembly.

Sample Compatibility & Compliance

The Model 5-0102 is validated for digestion of raw and treated wastewater, surface water, industrial effluents, and digested sludge matrices per Standard Methods for the Examination of Water and Wastewater (2022 Edition), Section 5220 B & C. Its thermal performance meets the stringent ramp-rate and plateau-hold requirements of ISO 6060:2022 Annex A for Class II digesters. When used with certified reagents (e.g., catalog nos. 5-0075, 5-0076, 5-0077, 8020, 8021), the system supports traceable calibration against NIST-traceable potassium hydrogen phthalate (KHP) standards. All digestion protocols are fully compatible with GLP documentation workflows and support audit-ready data capture when paired with time-stamped instrument logs.

Software & Data Management

While the Model 5-0102 operates as a standalone hardware module, its thermal parameters (setpoint, dwell time, actual block temperature) are logged via optional RS-232 or USB interface to LIMS-compatible software platforms. Integration with SMART Spectro and CODPlus instruments enables synchronized assay initiation, eliminating manual timer synchronization errors. Firmware supports user-defined method storage (up to 10 pre-programmed profiles), each retaining independent temperature/time settings and alarm thresholds. Audit trail functionality—including operator ID, date/time stamp, and parameter modification history—is available when connected to validated laboratory informatics systems compliant with FDA 21 CFR Part 11 requirements.

Applications

• Routine COD analysis in municipal wastewater treatment plants for process control and regulatory reporting (e.g., NPDES permit compliance).
• Total phosphorus (TP) and total chromium (Cr) digestion prior to ICP-OES or colorimetric detection—leveraging identical thermal kinetics and acid-resistant tube compatibility.
• Method validation studies requiring strict thermal profile replication across multiple instruments and laboratories.
• Educational laboratories conducting APHA-standardized water quality experiments where repeatability and safety are prioritized over throughput.
• Field-deployable QA/QC verification of portable spectrophotometers using pre-digested reference standards.

FAQ

Is the Model 5-0102 compatible with EPA-approved digestion methods?

Yes—it fulfills all thermal criteria specified in EPA Method 410.1 for reflux digestion and is routinely employed in EPA-certified environmental labs for compliance monitoring.
Can the unit be calibrated independently of the analyzer?

Yes—block temperature accuracy is verified using NIST-traceable PT100 probe calibrators; calibration certificates are issued per ISO/IEC 17025 requirements.
What maintenance is required for long-term thermal accuracy?

Annual verification of heater block emissivity and sensor drift is recommended; no routine lubrication or part replacement is necessary due to solid-state thermal architecture.
Does the digester support digestion for non-COD applications such as TN or TOC?

It supports persulfate-based total nitrogen (TN) digestion per ISO 11908; however, high-temperature catalytic combustion for TOC requires dedicated furnace systems and is outside this unit’s operational envelope.
Are 16 mm tubes supplied with the instrument?

No—tubes must be ordered separately; borosilicate glass tubes meeting ASTM E438 Type I, Class A specifications are recommended for repeated use.