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How is the COD testing instrument used?

by:BOQU     2022-03-02

COD detection instrument uses special oxidants such as potassium dichromate, heats and digests at high temperature (165℃), and uses single-chip microcomputer technology for data processing. COD rapid detector is widely used in industrial environment monitoring, sewage treatment and scientific research. Colleges and universities and other fields.

How is the COD testing instrument used?

1. Open the multi-purpose dissolver, preheat, and select the COD digestion method. Select a suitable range of prefabricated reagents, place the blank sample on the test tube rack, and select the same amount of prefabricated reagents as the test samples according to the number of water samples to be tested.

2. Use a pipette or a pipette to accurately take out 2ml of pure water, add a pre-made reagent test tube, make a blank sample (stick to the wall when using a pipette, be careful not to overdo it), and go deep into the mouth of the test tube to prevent taking out particles and liquids in test tubes).

3. Take 2ml of water samples to be tested, each sample corresponds to a water sample, and add other pre-made reagents according to step 3.

4. Tighten the cap of the test tube, shake the test tube up and down, so that the sediment at the bottom is completely separated from the water sample from the bottom (the reagent in the test tube will generate heat at this time). Please hold the lid to avoid burning your hands.

5. The temperature of the pyrolyzer was raised to 165°C, the blank sample and the sample were added in sequence, and heated for digestion for 20 minutes. The digestion time after cooling of the digestion apparatus was 20 minutes. Remove the capped test tube, place it on a test tube rack, and cool in a ventilated place. Test the tube until it cools to room temperature. 6. Turn on the water quality calibrator as required, preheat, and select the appropriate method or wavelength for measurement. Directly select COD (corresponding selection area).

7. Take out the sample from the cooling test tube, wipe the outer wall of the test tube with a dandruff-free mirror cloth or soft paper, and put it into the water quality detector for colorimetric operation.

8. First input blank sample, and perform zeroing operation according to the blank. Direct measurement basis for COD concentration (mg/L). At the same time, there is no need to unscrew the cap. The median level must be clear.

COD testing equipment maintenance:

1. The installation position of the COD measuring instrument should not be too fast, there should be no vortex, and the cable should not be lifted directly to take the probe. The direction of the probe's measurement slit should be consistent with the direction of the water flow (self-cleaning). The calibration method of the UVCOD analyzer is different from the traditional reagent method, which needs to be calibrated with the help of laboratory measurement results. Usually, manual cleaning is required once a week to ensure that the measurement window is clean and the instrument works properly. There are two points to be calibrated when calibrating: one is the distilled water sample (measurement frequency, COD value is 0); the other is the actual water sample (measurement frequency, COD value measured by the laboratory), and input these two data into the instrument for calibration.

2. In the routine maintenance and inspection of the conventional reagent method COD analyzer, the main purpose is to check whether the instrument is working normally. For example, check whether the pipeline entering and leaving the pipeline is smooth and whether there is leakage; keep the instrument clean, especially check and replace the rotating parts and wearing parts to prevent the leakage and corrosion of the instrument. Potassium cyanate.

3. Silver sulfate is a corrosive reagent, which is volatile and absorbs water in the workplace. It should be replaced regularly, usually at least once every 3 months. Peristaltic pumps often absorb strong corrosive reagents, and about 3 should be repaired or replaced. months to ensure its reliable operation. A comprehensive inventory of the measuring reactor can be carried out within a year.

4. The instrument has a set working curve when it leaves the factory, but due to different working conditions on-site, its working curve should be accurately calibrated. The COD standard solution can be prepared in the laboratory, and its calibration process is consistent with the measurement cycle. After calibration, change the relevant parameters and adjust the working curve.

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