CODcr-2001 Online Water Quality Chemical Oxygen Demand Analyzer
Typical Applications
The CODcr-2001 Online Water Quality Chemical Oxygen Demand Analyzer is developed based on the latest environmental protection standard HJ 377-2019 “Technical Requirements and Test Methods for Chemical Oxygen Demand (COD) Water Quality Online Automatic Monitoring Instruments”. It is widely used in environmental pollution source monitoring, industrial process water monitoring, municipal wastewater monitoring, wastewater treatment plant monitoring, and other fields.
Product Features
Advanced Sequential Injection Platform: Significantly reduces the number of components, featuring a simple structure that is easy to troubleshoot.
High-Precision Stepping Syringe Pump: Non-contact liquid dispensing design. Requires less dilution water for high-range measurements, ensuring stable dilution intervals.
10-Port Valve Flow Path: Utilizes laser etching technology for precise customization of groove dimensions and positioning. The valve core is made of sapphire material, offering extremely high surface wear resistance, long service life, and excellent stability.
Integrated Direct-Read/Colorimetric Unit: High absorbance resolution.
Liquid Reagents: Do not require low-temperature storage and can be preserved at room temperature for over 30 days.
Power Failure Protection Design: Data is not lost; automatically resumes operation upon power restoration.
Intelligent Fault Alarm & Auto-Reset Function: Automatic zero recovery in case of over-range anomalies.
Customizable Special Function Services: Ensures user-friendly and convenient operation.
Automatic Verification & Judgment Function: Complies with the requirements of HJ 355-2019 “Technical Specification for Operation of Water Pollution Source Online Monitoring Systems (CODcr, NH₃-N, etc.)”.
Turbulence Principle Technology & Innovative Automatic Direct-Air Cooling Device: Enhances digestion and cooling efficiency, shortening sample processing time.
Working Principle
The instrument’s measurement principle complies with the standard HJ 828-2017 “Water Quality – Determination of Chemical Oxygen Demand – Dichromate Method”. It employs the potassium dichromate method to rapidly digest samples under sealed, high-temperature, and high-pressure conditions. Dichromate completely oxidizes organic compounds in the water sample, simultaneously causing a change in the color of chromate ions. The degree of color change is proportional to the content of organic compounds in the sample. The COD value of the water sample is calculated by spectrophotometrically measuring the change in chromate ion color before and after the reaction and converting it.
Technical Specifications
| Specification | Technical Parameter |
| Range | 0～1000/2000/10000/20000/60000 mg/L, other ranges can be customized |
| **Indication Error *** | ±5% |
| Repeatability | ≤5% |
| Quantitation Limit | ≤15 mg/L |
| Resolution | 0.01 mg/L |
| 24h Hold Stability Drift | ±5 mg/L |
| 24h High Concentration Drift | ≤5% |
| Note | * Tested at 80% of the range concentration. |
Technical Specifications
(Common for CODcr/CODmn/TP/TN/AND/NO₃N)
| Specification | Technical Parameter |
| Minimum Maintenance Interval | ≥168 h/time |
| Measurement Modes | Scheduled Point Measurement, Cyclic Measurement, External Signal Trigger Measurement |
| Standard Solution Verification | Manual Verification, Automatic Verification |
| Instrument Calibration | Automatic Calibration, Manual Calibration |
| Automatic Cleaning | Automatic cleaning, cleaning cycle is configurable |
| Data Storage | Up to 3 years of data storage |
| Instrument Output | 2 channels of 4～20mA analog output; RS232/RS485 digital output |
| Power Requirements | 220V AC, 50Hz |
| Environmental Requirements | 5℃～40℃, Relative Humidity 65%±20%, Non-condensing |
| Installation Method | Wall-mounted, Floor-standing |
| Instrument Dimensions (H×W×D) | 550×450×330 mm (excluding pre-treatment system cabinet) |
| Instrument Weight | 30 kg |
Ordering Guide
The standard configuration includes: Main Unit, 1 Solid Reagent Kit (for 360 water samples), Operation Manual, 2 empty 10L Plastic Buckets, Installation Accessories, etc.
Users can also prepare reagents themselves; Dongrun provides the reagent formulations. For complex water samples, prior sample testing and confirmation are required. For any special requirements, please contact our Sales Department or local office.
Reagent Ordering Codes
| Product | Ordering Code | Product | Ordering Code |
| Chemical Oxygen Demand (CODcr) | CHEM-13-00B | Chemical Oxygen Demand (CODmn, Seawater) | CHEM-42-00 |
| Salicylate Ammonia Nitrogen | CHEM-28-00 | Acidic Permanganate Index (Freshwater) | CHEM-35-00 |
| Total Phosphorus (Freshwater) | CHEM-18-00B | Total Phosphorus (Seawater) | CHEM-47-00 |
| Total Nitrogen (Freshwater) | CHEM-29-00 | Total Nitrogen (Seawater) | CHEM-49-00 |
| Orthophosphate (Freshwater) | CHEM-39-00 |
Why Choose Dongrun Online Analyzers?
1μL High-precision Injection System Exclusive Patented Design.
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Accuracy
Replaces traditional peristaltic pumps with a more accurate injection pump, achieving precision to 1μL.
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Durable
The main components such as pumps and valves require no maintenance within one year.
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Cost-saving
Eliminates the need for pump tubing, saving on consumable replacements.
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Safety
Automatic activation of protective functions if the water tank is found to be empty, preventing pump damage.
Core Component Colorimetric Module Independently Developed and Manufactured
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The colorimetric module features reference light measurement functionality
It can mitigate interference from fluctuations in light sources or temperature changes on measurement results.
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50% increase in light source lifespan
Automatically controls light-on time to extends the lifespan of the light source, reducing aging.
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The program automatically adjusts the intensity of the light source
No manual intervention or maintenance required.
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The colorimetric module’s heating function is safe and reliable
Real-time monitoring of temperature rise rate, over-temperature alarm, and a fully enclosed design.
Advanced Quality Control Calibration System
| option | Regular brands | Dongrun | Value |
|---|---|---|---|
| Failure verification calibration | Manual adjustment in case of verification failure | Instrument automatically initiates recalibration in case of verification failure | More convenient |
| Selectable range | Only fixed range | High, medium, and low multiple ranges are available | Applicable range is more extensive |
| Verification method | Only range verification | Automatic zero-check and range verification, two methods | More accurate |
Low-Medium-High 3-in-1 Range System
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Three ranges
Instrument offers high, medium, and low three ranges.
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Customizable range values
Users can define range values for both the medium and high ranges. instrument will automatically adjust to match.
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Effortless operation
After switching between manual and automatic modes, there’s no need to recalibrate the instrument.
After changing the range, only single-point calibration is required, with no need for calibration of the working curve.
One-click waste discharge and one-click reagent filling.
Key operations are visualized, allowing real-time signal monitoring.
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Two modes of manual and automatic
In manual mode, users can select a specific range for measurement.
In automatic mode, the instrument will automatically switch ranges based on the measurement results.
