1. The heating unit of the black crystal glass adopts a new type of black crystal glass silver-coated conductive heating technology, which has an extremely long service life. It can withstand a temperature of 800℃. During heating, the surface of the electric furnace heats up evenly, and the heating and cooling speeds are fast.
2. The heating unit uses high-temperature resistant inorganic environmental protection insulation materials. The heat loss from the bottom plate and the periphery is small. The heating and heat conduction are uniform, and the thermal efficiency is higher.
3. The flat high-temperature resistant glass panel is flat, smooth and easy to clean. If the surface is contaminated, it can be wiped dry with a cloth, which can reduce the damage to the instrument caused by improper operation.
4. The upgraded glass reflux condenser with a thorn-like design and a heat dissipation system provides excellent digestion and reflux performance, ensuring the parallelism and accuracy of the sample digestion results.
5. According to the different heating powers selected by the user, the surface heating temperature of the electric furnace can be displayed.
6. The digestion time can be set. After digestion is completed, the instrument automatically stops heating. The instrument fan continues to work for half an hour to assist in cooling the sample, which can be left unattended.
7. It saves electricity and water, is safe and reliable, and improves the working efficiency of the operator.

Precautions:
1. Check the equipment status before use: Inspect the power cord, digestion tubes, and heating module to ensure they are in good condition and free from damage or leakage to prevent safety hazards.
2. Confirm the compatibility of reagents and samples: Use freshly prepared reagents and ensure their type and concentration match the instrument model and detection method to avoid corrosion or abnormal reactions.
3. Accurately add samples and reagents: Use precise pipetting tools to add samples and reagents according to standards to avoid volume errors that could affect COD results.
4. Thoroughly mix before digestion: After adding concentrated sulfuric acid and other reagents, shake well to prevent violent local reactions that could cause boiling over or tube breakage.
5. Do not open the lid during digestion: To avoid heat loss, temperature fluctuations, and the leakage of harmful gases, ensuring experimental safety and data accuracy.
6. Wear personal protective equipment: Including heat-resistant gloves, goggles, and lab coats to prevent injury from high temperatures and corrosive reagents.
7. Dispose of waste liquids properly: Waste liquids containing potassium dichromate, mercury sulfate, etc., are hazardous waste and must be collected centrally and handed over to professional institutions for treatment; direct dumping is strictly prohibited.
8. Clean and maintain the equipment promptly after use: Clean the digestion tubes immediately after cooling to avoid residual contamination; regularly inspect the heating module, temperature sensor, and other components to extend the equipment's lifespan.