1、 Overview of COD Constant Temperature Heater:

The HX12 COD constant temperature heater is a heating reflux device that uses air condensation instead of water condensation to measure chemical oxygen consumption.

COD constant temperature digestion instruments can be widely used in industries such as environmental protection, higher education, medicine, health, food, tap water, chemical industry, sewage treatment, papermaking, petrochemicals, metallurgy, printing and dyeing, making COD measurement efficient, fast, and economical.

COD constant temperature digestion instrument

2、 Main technical indicators of COD constant temperature heater:

1. Temperature range of COD constant temperature heater: 32°C ~ 399°C

2. Accuracy of COD constant temperature heater: ±1°C

3. Heating time of COD constant temperature heater: (170°C) <30min

4. COD constant temperature heater temperature setting: 0-99 hours; 0-99 minutes; 0-99 second segmented adjustable

5. COD constant temperature heater power: 1200W

6. COD constant temperature heater power supply: AC220V 50Hz

7. Heating holes for COD constant temperature heater: 12

3、 Installation and use of COD constant temperature heater:

1. After unboxing the COD constant temperature heater, install the test tube rack according to the attached diagram, check that there are no abnormalities in the host, and then connect the power supply. Turn on the power switch, and the heating indicator light of the temperature control instrument will light up, indicating that the instrument is normal.

2. Insert the thermometer into the temperature measuring hole, adjust the temperature controller, and set the heating temperature to the desired heating temperature (usually around 170 ° C). At this point, the thermometer indicates the actual heating temperature. Wait for about 30 minutes, and the heating indicator light will turn on and off, indicating that the constant temperature stable state has been reached.

3. Connect the power supply, turn on the power switch, and the power indicator light will turn on. Insert the thermometer into the test hole and heat it for 30 minutes to reach the preset temperature (based on the temperature displayed on the thermometer, the thermometer needs to be configured by oneself).

At this point, the time controller starts timing and maintains a constant temperature state. After reaching the set time of 120 minutes, the temperature will automatically shut down. (The time unit displayed on the PID temperature control meter is minutes)

5. According to the measurement conditions shown in Table 5-1 on page 156 of the Environmental Monitoring Analysis Method, take 20mL of water sample and add 10mL of 0.25N K2Cr2O7, Ag2SO4-H2SO4 30mL， Add dozens of small porcelain stones and gently shake the heating tube to make the solution uniform, in order to prevent boiling.

6. Connect the condenser tube to the heating tube and place it in the heating hole that has been kept at a constant temperature. After about 15 minutes, the solution begins to boil and continues to heat and reflux.

7. After refluxing for 2 hours, carefully remove the heating tube and condenser tube and place them in the bracket. After cooling, rinse the condenser tube wall and grinding mouth with water, remove the condenser tube, pour the solution in the heating tube into a 500mL triangular flask, dilute with water to 140 mL, and titrate with 0.1N ferrous ammonium sulfate.

4、 Precautions for using COD constant temperature heater

1. For water samples with high chemical oxygen demand (or high suspended particulate matter content), an appropriate amount of sample can be taken for multiple dilutions. After taking an appropriate amount for analysis, the original amount of wastewater taken during dilution should not be less than 5ml.

2. The COD constant temperature heater must start heating after the heater temperature remains constant.

3. When inserting the thermometer, be careful and handle it gently to avoid breakage. After reaching the working temperature, the thermometer can be removed.

Before heating the heat pipe, small ceramic particles must be added, and the solution should be shaken well. Glass balls should not be used as a substitute to prevent boiling. After using up the small ceramic particles, rinse them with deionized water or distilled water, and dry them for later use. Do not remove small ceramic particles soaked in water and put them into a heating tube for heating, otherwise there is a risk of explosion and boiling!

During the process, avoid dropping sulfuric acid on the wall of the heating tube.

If the concentration of chloride ions in water is greater than 300mg/L, HgSO4 can be added according to the standard method to prevent interference.

After reaching a constant temperature, the thermometer can be removed to avoid breakage.

8. It is strictly prohibited for corrosive substances to spill onto the heater.

When opening the cover to inspect the instrument, the power should be disconnected.

10. Do not use the temperature controller above 200 ℃ to avoid damaging it and causing consequences at your own risk.