CODMAX sc dichromate COD online analyzer

Measuring principle:

• This online COD analyzer uses the potassium dichromate method to measure COD: a mixture of water sample, potassium dichromate, silver sulfate solution (used as a catalyst to enable more complete oxidation of straight-chain aromatic hydrocarbon compounds) and concentrated sulfuric acid is heated to 175°C in the digestion cell. During this period, chromium ions as an oxidant are reduced from valence VI to valence III, causing a color change. The degree of color change corresponds to the content of organic compounds in the sample. The online COD analyzer directly displays the COD of the sample through colorimetric conversion.

• The main interfering substance is chloride, which is removed by adding mercury sulfate to form a complex.

Instrument features:

• The classic potassium dichromate oxidation is combined with highly efficient digestion, complying with the Chinese national standard dichromate method COD testing principle.

• This online COD analyzer is equipped with an accurate optical metering system and has an automatic calibration function, making measurement more accurate.

• It can be connected to HACH sc200 and sc1000 controllers, offering good expandability.

• 10~5000 mg/L three-range automatic switching, with no need to determine the range of the water sample COD.

• The optimized internal structure of this online COD analyzer makes comparison between online data and laboratory data easier.

• It has an automatic cleaning function. Combined with piston pump technology and a corrosion-resistant tubing design, maintenance is reduced.

Technical specifications

• Measuring method    Potassium dichromate high-temperature digestion, colorimetric determination

• Measuring range    10～5,000 mg/L

• Indication error    (potassium hydrogen phthalate test) ±8%

• Repeatability    ≤3%

• Zero drift (24 h)    ±5 mg/L

• Range drift (24 h)    ±10 mg/L

• Digestion time    Automatic, selectable at approximately 3, 5, 10, 20, 30, 40, 60, 80, 100 or 120 minutes

• Measurement interval    Continuous measurement, 1~24 hour interval measurement, trigger-start measurement, user-defined interval

• Calibration    Selectable no calibration, automatic calibration or user-defined calibration (up to 5 points)

• Output    2 current outputs: 0/4-20 mA, maximum load 500Ω

• 2 multifunctional output relays: 24V 1A

• Read via SD card on sc200 or sc1000 controller

• Service interface    RS232

• Digital communication    MODBUS or Profibus, via sc200 or sc1000 controller

• Display    Via HACH sc200 or sc1000 display

• Ambient temperature    +5~+40℃

• Power supply    220 VAC ±10%/50-60 Hz

• Power consumption    Approx. 100VA

• Dimensions    535.80 mm× 711.5 mm× 376 mm

• Weight    Approx. 38 kg  (excluding reagents)

Related reagents

Spare parts

Ordering guide

• 9302600 CODmax plus sc    Online automatic chemical oxygen demand analyzer

• LCW420    Analyzer reagent

• Note: The above CODmax plus sc order numbers do not include the sc controller. Please order the corresponding sc200 or sc1000 controller as required.

Source: Public information from the HACH water quality website