|Range||MDL||Method||Kit Catalog No.||Refill Catalog No.|
|0-20 ppb||2 ppb||Rhodazine D||K-7511||R-7511|
|0-40 ppb||2.5 ppb||Rhodazine D||K-7540||R-7540|
|0-100 ppb||5 ppb||Rhodazine D||K-7599||R-7540|
|5-180 ppb||5 ppb||Rhodazine D||K-7518||R-7518|
|0-1 ppm||0.025 ppm||Rhodazine D||K-7501||R-7501|
|1-12 ppm||1 ppm||Indigo Carmine||K-7512||R-7512|
|Range||Method||Kit Catalog No.|
|0-1.000 ppm||Rhodazine D||K-7553|
|0-15.0 ppm||Indigo Carmine||K-7513|
|0-15.0 ppm||Indigo Carmine||I-2002|
The level of dissolved oxygen in natural waters is often a direct indication of quality, since aquatic plants produce oxygen, while microorganisms generally consume it as they feed on pollutants. At low temperatures the solubility of oxygen is increased; during summer, saturation levels can be as low as 4 ppm. Dissolved oxygen (D.O.) is essential for the support of fish and other aquatic life and aids in the natural decomposition of organic matter. Waste treatment plants that employ aerobic digestion must maintain a level of at least 2 ppm dissolved oxygen.
At elevated temperatures, oxygen is highly corrosive to metals, causing pitting in systems such as high-pressure boilers and deep well oil recovery equipment. To prevent costly corrosion damage, the liquids in contact with the metal surfaces must be treated, usually by a combination of physical and chemical means. Deaeration can reduce the dissolved oxygen concentration of boiler feedwater from several ppm to a few ppb. Chemical reducing agents such as hydrazine, DEHA, or sodium sulfite, may be used instead of or in conjunction with deaeration.