Water Color Comparison Tube

Features: 1. Convenient-small size and light weight , the test can be conducted without any other laboratory equipment and skilled people: 2. Fast-only need 3-5minutes to test one sample no need extra material or instrument easy to operate; 3. Precise-all test parameters are according to international standards 4. Portable -PE plastic tube , small size , light weight; 5. Sealed by aluminum foll , long shelf life , 18 month under normal temperature.
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water color comparison tube

water color comparison tube


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COD test tube



COD test tube


water color comparison tube

What is chemical oxygen demand (COD)?

    The so-called chemical oxygen demand (COD) is the amount of oxidant consumed when a certain strong oxidant is used to treat water samples under certain conditions. It is an indicator of the amount of reducing substances in the water. Reducing substances in water include various organic substances, nitrites, sulfides, and ferrous salts. But the main ones are organics. Therefore, chemical oxygen demand (COD) is often used as an indicator to measure the amount of organic matter in water. The greater the chemical oxygen demand, the more serious the water pollution by organic matter. With regard to the determination of chemical oxygen demand (COD), the measured values will vary with different measuring methods and reducing methods in water samples. At present, the most commonly used methods are acid potassium permanganate oxidation and potassium dichromate oxidation. The potassium permanganate (KmnO4) method has a low oxidation rate, but it is relatively simple. It can be used when determining the relative comparison value of the organic content in water samples. The potassium dichromate (K­2Cr2O7) method has high oxidation rate and good reproducibility, and is suitable for measuring the total amount of organic matter in water samples. Organic matter is very harmful to industrial water systems. Water containing a large amount of organic matter will contaminate the ion exchange resin when passing through the desalination system, and it is particularly easy to contaminate the anion exchange resin, reducing the resin exchange capacity. Organic matter can be reduced by about 50% after pretreatment (coagulation, clarification, and filtration), but it cannot be removed in the desalination system, so it is often brought into the boiler through make-up water to reduce the pH of the boiler water. Sometimes organic matter may also be brought into the steam system and condensed water, reducing the pH and causing system corrosion. High levels of organic matter in the circulating water system will promote microbial reproduction. Therefore, no matter the desalination, boiler water or circulating water system, the lower the COD, the better, but there is no uniform limit indicator. When the COD (DmnO4 method)> 5 mg / L in the circulating cooling water system, the water quality has begun to deteriorate.

Chemical oxygen demand is also called chemical oxygen demand (COD). It is the use of chemical oxidants (such as potassium permanganate) to oxidize and decompose oxidizable substances (such as organics, nitrites, ferrous salts, sulfides, etc.) in suspended water, and then calculate the oxygen consumption according to the amount of residual nitrating agent The quantity, which is the same as BOD, is an important indicator of water pollution. The unit of COD is ppm or milligram per liter. The smaller the value, the lighter the water pollution degree.

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