Shentai ST106BW Water-Cooled COD Reflux Digestion System
| [Brand | Shentai (SENTE) |
|---|---|
| Origin | Shandong, China |
| Manufacturer Type | Direct Manufacturer |
| Product Category | Domestic |
| Model | ST106BW |
| Digestion Method | Reflux Digestion |
| Heating Module | Dual Independent Heating Blocks |
| Batch Capacity | 15 Samples |
| Temperature Range | 0–200 °C |
| Temperature Accuracy | ±1 °C |
| Digestion Vessel Capacity | 220 mL |
| Timer Accuracy | ±1 min] |
Overview
The Shentai ST106BW Water-Cooled COD Reflux Digestion System is an engineered solution for compliant, reproducible chemical oxygen demand (COD) determination in accordance with HJ 828–2017 — the Chinese national standard equivalent to ISO 6060 and aligned with core principles of APHA Standard Methods 5220B (Closed Reflux, Colorimetric Method). It implements precise thermal control over the dichromate-based oxidation process under reflux conditions, where organic matter in water samples is quantitatively oxidized by potassium dichromate in strong acidic medium (H₂SO₄) at elevated temperature (typically 150–160 °C) for a defined duration (120–130 min). Unlike open-heating or air-cooled alternatives, this system employs a closed-loop water circulation cooling mechanism integrated with dual PID-regulated heating blocks, ensuring stable micro-boiling conditions across all 15 digestion positions. Its architecture eliminates operator-dependent variability in temperature ramping, reflux maintenance, and cooling timing — critical factors influencing Cr(VI) reduction completeness and spectrophotometric absorbance linearity.
Key Features
- Dual independent heating blocks with real-time PID temperature regulation, delivering uniform thermal distribution across all 15 digestion vessels (220 mL capacity each) and minimizing inter-position deviation.
- Integrated closed-loop water cooling system replaces wasteful tap-water condensation, reducing water consumption by >90% while maintaining consistent reflux condensate return rate and preventing vapor loss.
- Automated digestion cycle: one-touch initiation triggers sequential heating to target temperature (user-selectable within 0–200 °C), automatic 120/130-minute countdown under reflux, and thermal shutdown upon completion.
- Motorized spherical reflux condenser with programmable vertical lift mechanism — enabling safe, ergonomic access to digestion tubes without manual disassembly.
- 7-inch capacitive touch display with graphical interface showing live temperature per zone, remaining time, system status, and error diagnostics.
- On-board acid addition and post-digestion rinse function via precision dispensing nozzle mounted above the condenser inlet — eliminating manual pipetting and cross-contamination risk.
- Front-access sliding digestion chamber with full-depth drawer design for rapid sample loading/unloading and compatibility with standard 24/40 ground-glass joint COD digestion tubes.
Sample Compatibility & Compliance
The ST106BW accommodates standard 220 mL borosilicate glass digestion tubes conforming to HJ 828–2017 dimensional and thermal shock specifications. It supports aqueous matrices including surface water, municipal wastewater, industrial effluents, and leachates with COD concentrations ranging from 10 to 700 mg/L (dilution-adjusted). All thermal and timing parameters are traceably calibrated against NIST-traceable reference thermometers and certified quartz timers. The system’s operational protocol satisfies the method-defined requirements for “reflux at gentle boil for 120 minutes” and meets internal quality control benchmarks for repeatability (RSD ≤ 3.2% for duplicate digestions, n = 10) and recovery (92–105% for potassium hydrogen phthalate standards). While not CE-marked or FDA-registered, its procedural fidelity aligns with GLP documentation expectations for environmental testing laboratories seeking CNAS (ISO/IEC 17025) accreditation.
Software & Data Management
The embedded firmware supports local data logging of all active cycles: date/time stamp, setpoint temperature, actual zone temperatures (recorded every 30 s), elapsed digestion time, and completion status. Cycle logs are exportable via USB flash drive in CSV format for integration into LIMS or QA/QC review workflows. No cloud connectivity or remote access is implemented — consistent with data sovereignty requirements in regulated environmental testing environments. Audit trail functionality records user login events, parameter modifications, and emergency stop activations, supporting basic 21 CFR Part 11 readiness when paired with institutional electronic signature policies.
Applications
- Routine COD analysis in municipal wastewater treatment plants for process monitoring and discharge compliance reporting.
- Environmental monitoring stations conducting surface water quality assessment under national surface water quality standards (GB 3838–2002).
- Industrial environmental labs performing pretreatment verification for electroplating, textile dyeing, pharmaceutical, and food processing effluents.
- Academic and research laboratories requiring standardized, hands-off reflux digestion for method validation studies or inter-laboratory comparison exercises.
- Third-party testing organizations executing contract analyses under HJ 828–2017, where documented adherence to prescribed thermal and temporal parameters is mandatory.
FAQ
Does the ST106BW comply with international standards such as ISO 6060 or ASTM D1252?
It is designed to replicate the thermal and reflux conditions specified in HJ 828–2017, which is technically harmonized with ISO 6060:1989 (E) for dichromate reflux methodology. However, formal ISO/IEC 17025 method validation must be performed by the end-user laboratory.
Can the system be used for chloride interference correction protocols?
Yes — the adjustable temperature range (0–200 °C) and precise timer support modified digestion protocols, including pre-treatment steps for high-chloride samples using mercury sulfate masking or silver nitrate precipitation, provided reagent addition is performed manually prior to loading.
Is the water cooling system compatible with standard laboratory chilled water supply?
No — it operates as a self-contained recirculating unit with integrated reservoir and pump; connection to external chillers is neither required nor supported.
What maintenance is required for long-term reliability?
Monthly descaling of the water reservoir and condenser coil using dilute citric acid solution is recommended; annual calibration of temperature sensors using a reference thermometer is advised for continued accuracy assurance.
Are spare digestion tubes and condensers available as consumables?
Yes — Shentai supplies OEM-certified 220 mL borosilicate digestion tubes and PTFE-jacketed spherical condensers with standardized 24/40 joints, ensuring mechanical and thermal compatibility.
