Automatic COD Monitor

High-performance Automatic CODMN Monitor Can Achieve Regulation and Compliance with Advanced Technology and More Than 30 Years of Accumulated Expertise

Division: Water Pollution
Manufacturing Company: HORIBA Advanced Techno Co., Ltd.
  • Uses only 1/10 the reagent of the existing systems
    Ower unique dispensing and quantification device enable the CODA-500 to maintain measurement accuracy while using only 1/10 the quantity of reagent required. A reagent delivery service also eliminates the need for time-consuming reagent preparation. This reduces the time and trouble involved in reagent replacement and cuts running costs in half.
  • Touch panel LCD makes operation easier
    The use of a color LCD with a touch panel makes operation intuitive, and lower power consumption reduces environmental load. These and other functions attuned to the times will enable the system to meet future water quality management needs.
  • Cuts power consumption in half
  • Direct heating method requires no cooling water
  • Full range of interface options (RS-232C, RS-485, USB, and MODBUS®)
  • 2 Lines for Different Types of Samples and Applications

    Acid Potassium Permanganate Method (CODA-500-A/CODA-500-C)

    Under acidic conditions, chloride ions are also oxidized by potassium permanganate. To prevent these ions from reacting, a silver nitrate solution must be added to cause the chloride ions to be precipitated as silver chloride. For this reason, the acid method is suitable when the concentration of chloride ions in the sample solution is low (no more than 10 times the full scale of the measurement range).

    Alkaline Potassium Permanganate Method (CODA-500-B)

    When measuring sample water such as seawater that includes many chloride ions, it would be impossible to eliminate the interference effect of the chloride ions with the acid method. For these types of samples, the alkaline method is used. With the alkaline method, the chloride ions are not oxidized by potassium permanganate, so COD can be measured without the interference effect of the chloride ions.

*COD : Chemical Oxygen Demand


General specification Name of equipmentAutomatic COD monitor 
Model CODA-500
Object COD concentration in water
Dimensions 600 (W) mm × 510 (D) mm × 1600 (H) mm*1
Mass Approx. 150 kg
Power source 100 V to 240 V AC ±10%, 50 Hz/60 Hz
Power consumption
  •  100 V to 120 V AC: Approx. 250 VA
  •  120 V to 240 V AC: Approx. 350 VA
Installation conditions
  • Indoor installation type
  •  Transient overvoltage of main power source: Overvoltage category II (EN61010-1), pollution level 2
PerformanceMeasurement range
(Actual upper limit of measurement is half-scale of the range.)
  • 0 mg/L to 20 mg/L
  • 0 mg/L to 30/40/50/100/200/500/1000/2000 mg/L (1-dilution type)
Reproducibility (with standard
solution for glucose)
20 mg/L: Within ±1% of full-scale value
30 mg/L to 500 mg/L: Within ±2% of full-scale value
1000 mg/L to 2000 mg/L: Within ±5% of full-scale value
Optional specification*2: Within ±5% of full-scale value
StabilityZero drift
(for 24 h)
20 mg/L: Within ±3% of full-scale value
30 mg/L to 500 mg/L: Within ±4% of full-scale value
1000 mg/L to 2000 mg/L: Within ±5% of full-scale value
Optional specification*2: Within ±5% of full-scale value
Span drift
(for 24 h, with
standard solution
for glucose)
20 mg/L: Within ±3% of full-scale value
30 mg/L to 500 mg/L: Within ±4% of full-scale value
1000 mg/L to 2000 mg/L: Within ±5% of full-scale value
Optional specification*2: Within ±5% of full-scale value
(acidic method)
Acid potassium permanganate method at 100℃
(based on JIS K 0806)
(alkaline method)
Alkaline potassium permanganate method at 100℃
(acidic method)
Acid potassium permanganate method at 100℃
(based on JIS K 0806)
With reagent cleaning function
Number of measurement pointsStandard: 1
Optional: 2
Measuring rangeStandard: 1 range
Optional: 2 ranges
Heating methodDirect heating
End point detectionPotentiometric titration at constant current
Titration methodMicro syringe titration
Measurement interval60 minutes
Reagent cleaningCODA-500-A, CODA-500-B: Not available
CODA-500-C: Available
Method without adding a silver
nitrate solution*4
(by selecting this method when the chloride ion concentration is low)
Ambient temperature2℃ to 40℃
Ambient humidityRelative humidity: 85% max. (without condensation)
Power supply voltage
100 V to 240 V AC ±10%
Sample water
Temperature2℃ to 40℃ (without freezing)
Flow rateWhen the overflow tank (optional) is used
0.5 L/min to 5 L/min (depends on the overflow tank type)
Chloride ion
concentration (for
acidic method)
CODA-500-A: Up to 1 time the full-scale value
CODA-500-C: Up to 100 times the full-scale value (maximun)*6
(The alkaline method is not influenced by chloride ion concentration.
For more than 100 times the full-scale value, select the alkaline
Sampling pointPiping length from main unit: Within 3 m
Supply methodStandard: Waterworks water
Optional: Supply from deionized water tank
Water quality*5Waterworks water without COD components
(hardness: 100 mg/L max.)
Water supply
100 kPa to 500 kPa (at the connection of the instrument inlet)
Consumption20 mL to 420 mL per measurement run (depends on the
measurement range and cleaning function setting).
Installation conditions
  • Well ventilated indoor location without exposure to direct sunlight
  • Flat and stable location with minimized vibrations and shocks
  • Atmosphere free from dust, mist, corrosive gas, etc.
DisplayColor LCD with touch panel
Number of pointsStandard: 3
Optional: 6
KindsStandard 4 mA to 20 mA DC, 0 mA to 16 mA DC
(4 mA to 20 mA DC is set at the factory. 0 mA to 16 mA DC is
selectable on the screen.)
Optional: 0 mA to 16 mA DC, 0 V to 1 V DC, and 1 V to 5 V DC
DescriptionCOD concentration, time COD load, and time flow rate
Output impedance900Ωmax.
Number of pointsStandard: 14
Optional: 21
FormatNo-voltage contact output
KindsInsulated output
Output capacity250 V AC, 3 A
30 V DC, 3 A
(Only 30 V DC, 3 A are available for "Maintenance" contact.)
Status outputMeas., Cal., Standby, Cleaning, Blank Meas., Synchro. Idle 1,
Synchro. Idle 2, Maintenance, Power, etc.
Warning outputLimit warnings (COD Hi limit, Flow limit, and COD Hi Load), COD H.Hi limit, Sample Lack, Total Alarm 1 to 6, various gauge errors, etc. (optional: Lack Reagent)
Number of pointsStandard: 1
Optional: 2
KindsStandard: 4 mA to 20 mA DC input
Optional: 1 V to 5 V DC
DescriptionFlow signal (full-scale value may be specified freely)
Number of pointsStandard: 9
Optional: 17
FormatNo-voltage a-contact input (open collector is available)
KindsInsulated type input: common to (-) side
ON resistance100Ω max.
Open voltage26 V DC max.
13 mA DC max.
FunctionsMeas. Start, Cal. Start, Cleaning Start, Blank meas. Start, Modify
Date, Samp. Lack, Line Select, Flow Mainte, Flow Err., Flow Power
OFF, and Flow No Drain
Load calculation capabilityCOD load calculation capability
Storage capabilityData retention for 1 year (measurement values)
External USB storage is available.
Communication capabilityStandard: RS-485
Optional: RS-232C
Communication protocolModbus
PrinterProvided (58 mm); with automatic take-up device
Potassium permanganate
Reagent A
2 mL per measurement run
Sodium oxalate
Reagent B
1 mL per measurement run*8
Sulfuric acid solution
Reagent C
1 mL per measurement run
Silver nitrate solution
Reagent D
0.5 mL per measurement run (used for acidic method)
Sodium thiosulfate solution
Reagent E
2 mL per measurement run (used for reagent cleaning function)
Sodium hydroxide solution
Reagent F
1 mL per measurement run (used for alkaline method)
Reagent replacement interval1 month or more.
Tap water20 mL to 420 mL per measurement run (depends on the
measurement range)

*1:  Channel-based compatibility with the former CODA-200 series products is available (standard).
*2:   This means the optionally addable specifications such as 2-point measuring, 2 ranges and reagent line cleaning,and also means using the reagent cleaning function of CODA-500-C.
*3:   To be specified when you place an order.
*4:   If silver nitrate is not used, the performance in the specifications is not warranted.
*5:   If tap water is used, first perform flushing for about 30 minutes and then send tap water to the CODA-500.For the version using a tank, use deionized water of 10 mS/m (=1.0 μS/cm) maximum.
*6:   When the reagent cleaning function is not used, the concentration is up to 1 time the full-scale value. The setting of reagent cleaning function can be switched depending on the chloride ion concentration in the sample water.
*7:   Use the reagents designated by our company. If any other reagents are used, no measured values are warranted.When reagent cleaning function is set, reagent consumption may grow.
*8:   Use sodium oxalate for the oxygen method or sodium oxalate containing 0.1 g/L manganese sulfate for the alkaline method.

The total volume control of water quality at companies which discharge waste water to a closed water area is implemented by the environmental agency. This regulation requires using a conversion equation for the method of obtaining the correlation between the values measured with an automatic COD monitor and those (by the designated measurement method) measured through the manual analysis specified in 17 of JIS K 0102. Before use, conduct the manual analysis and enter the conversion factor to the CODA-500.

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