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Common faults and troubleshooting methods of COD analyzer

by:BOQU     2022-10-16

COD analyzer is a chemical oxygen demand testing instrument. Quickly and accurately measure the chemical oxygen demand of sewage in the laboratory. It is the necessary experimental equipment for environmental monitoring stations, environmental engineering technicians, and enterprise laboratories. The measurement principle is the rapid catalytic method (chromium method). In the application of cold light source display technology, the life of the light source lamp is as long as 100,000 hours, and the switching of the optical path for measuring parameters is changed from manual to automatic switching, eliminating the error factor of artificial rotation.

Technical advantages:

1. Data transmission: transmit current and historical data to the computer;

2. Direct reading of concentration: fast and accurate determination of ammonia nitrogen concentration in wastewater;

3. Light source life: cold light source. Narrow-band interference. Light source life is up to 100,000 hours;

4. Display screen: large screen display 4.3-inch TFT color screen display, user-friendly interface operation;

5. Memory curve: 5 manufacturer curves, 195 expansion curves, a total of 200;

6. Curve correction: support automatic curve correction and automatic saving;

7. Colorimetric method: Support two colorimetric methods of the cuvette and colorimetric tube at the same time;

9. Data storage: historical data storage (date. time. parameters. measurement results) can choose machine storage or USB storage;

9. Curve customization: Customize the high-precision curve according to the customer's measurement range, improve the analysis and measurement accuracy, and support the customer to establish a segmented curve of the instrument. The segmental coefficient is determined according to the concentration.

Operational analysis steps:

When the CODcr concentration is 5.0-200mg/L(CODcr_L), 200-1000mg/L(CODcr_M), 1000-2000mg/L(CODcr_H):

Preparation of blank sample Take 2.0mL of distilled water and put it in a CODcr prefabricated test tube (select a suitable range), and shake with a stopper.

Sample preparation Take 2.0ml of the sample to be tested and place it in a CODcr prefabricated test tube (choose an appropriate range), and shake it up with a stopper.

When the temperature of the digester for digestion reaches 165 °C, insert the digestion colorimetric tube into the hole of the digestion furnace, in turn, cover the protective cover, and carry out digestion (for details, see DIS-16/25/30/36 Multifunctional CNC digestion for details. instrument manual), the buzzer alarms after 15min of digestion.

Cool and take out the digestion colorimetric tube into a dry beaker, cool naturally for 2 minutes, then cool it with water to room temperature, then place the digestion colorimetric tube on the test tube rack until all the sink to the bottom of the tube, and test on the machine.

Common faults and troubleshooting methods of the COD analyzer

1. The indication value is unstable: the blank measurement is abnormal or the injection pipeline. The dilution water pipeline is caused by air bubbles. The heating amount of the reagent is not allowed, add it again. Clean the electrode and replenish the internal solution of the comparison electrode. Remove air bubbles and clean lines.

2. Abnormal zero point indication, negative drift: check the flow path system; readjust the heating temperature, and check the concentration of sodium oxalate and potassium permanganate.

3. Negative drift of the indicated value: the blank calibration has not been carried out, the concentration of sodium oxalate and potassium permanganate is incorrect, the sample injection and the amount of reagent are incorrect, and the electrode is polluted. Perform blank correction again. reformulate. Re-inject and weigh reagents, remove line contamination and air bubbles, and clean or replace.

4. Positive drift of indicated value: clean and remove; replace low-content dilution water, and check the concentration of each solution

5. The indicated value is abnormally high: replace the low-content dilution water, check the concentration of each solution, and change the instrument range to a high-grade one.

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