JQ-100 typeStandard COD digester (5 tubes)

The national standard HJ 828-2017 specifies the steps for determining the chemical oxygen demand (COD) of water quality, and strictly specifies the conditions and indicators such as heating and digestion time, dissolved acidity, and the dosage of oxidants and catalysts for the measured samples. It is obvious that there are strict conditions for the determination of COD in water quality.

JQ-100 type standard COD digester (5 tubes)）Following the basic principles of ISO and HJ828-2017 standards, the digestion operation with reflux heating for 2 hours is ensured, and the preparation and addition of reagent solution are consistent with the national standard to ensure the accuracy of the analysis results.

The JQ-100 standard COD digester adopts microcomputer technology for timed control of the heating electric furnace, which can simultaneously heat 5, 6, and 10 digester bottle reflux devices. Thus achieving the goal of energy conservation and efficiency improvement. The instrument uses a glass burr reflux tube instead of a spherical reflux tube, and replaces water cooling with air cooling technology to improve the stability and safety of the instrument.

Standard COD digesterSuitable for the determination of COD in surface water, domestic sewage, and industrial wastewater. Not applicable for the determination of COD in water with chloride concentration greater than 1000mg/L (diluted). When the sampling volume is 10.0mL, the detection limit is 4mg/L and the lower limit of determination is 16mg/L. The upper limit for undiluted water samples is set at 700mg/L. If it exceeds this limit, it must be diluted and measured.

Technical specifications:

Measurement range: 10-700mg/L (measured after dilution of water samples greater than 700mg/L)

Measurement time: no more than 2 hours

Measurement error: Potassium hydrogen phthalate standard solution (500mg/L): relative standard deviation not exceeding 5.0%; Industrial organic wastewater (500mg/L): relative standard deviation not exceeding 8%

Environmental temperature: 5-40 ℃

Heating power: 1200W

Sample processing and determination methods refer to the national standard analytical method HJ828-2017

1. Add 3-5 explosion-proof ceramic beads to a 250mL conical flask with a standard grinding mouth on the 24th.

2. Add 10ml of sample.

3. Add 2mL of mercuric sulfate solution.

4. Add 5.0mL of potassium dichromate standard solution and shake well.

5. Connect the conical bottle to the lower end of the burr condenser tube.

6. Slowly add 15mL of silver sulfate sulfuric acid reagent from the top of the condenser tube to prevent the escape of low boiling point organic matter,

The conical flask should be continuously rotated to mix evenly.

7. After pressing the "Start" button, heat and dissolve.

8. After the instrument is heated and cooled, add 45mL of distilled water from above the condenser tube.

9. Remove the conical flask.

10. After cooling the solution to room temperature, add 3 drops of ferrous indicator solution and mix evenly. Using ferrous sulfate

The endpoint of ammonium standard titration solution titration is when the color of the solution changes from yellow to blue-green to reddish brown. remember

Calculate the consumption volume of ammonium ferrous sulfate standard solution according to the method standard.