Dissolved oxygen detection in boiler water

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Overview

The method for detecting dissolved oxygen in boiler water involves aquatic plants producing oxygen, but organic microorganisms typically consume oxygen when feeding on pollutants. Therefore, the dissolved oxygen content in natural water is a direct reflection of water quality. The solubility of oxygen is enhanced at low temperatures; The saturation of oxygen in summer should be reduced to 4ppm. Dissolved oxygen is an essential substance for fish and aquatic organisms to sustain life, and helps with the natural degradation of organic matter. When using aerobic digestion in sewage treatment plants, it is also necessary to ensure that the dissolved oxygen content is not less than 2ppm.

Product Details

Dissolved oxygen detection in boiler waterColorimetric testing kit

scope	MDL	method	Catalog Number	Supplement product number
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 method	K-7512	R-7512

Colorimetric testing kit

scope	method	Catalog Number
0-1.000 ppm	Rhodazine D	K-7553
0-15.0 ppm	Indigo carmine method	K-7513
0-15.0 ppm	Indigo carmine method	I-2002

Dissolved oxygen detection in boiler watermethod

Aquatic plants produce oxygen, but organic microorganisms usually consume oxygen when feeding on pollutants, so the dissolved oxygen content in natural water is a direct reflection of water quality. The solubility of oxygen is enhanced at low temperatures; The saturation of oxygen in summer should be reduced to 4ppm. Dissolved oxygen is an essential substance for fish and aquatic organisms to sustain life, and helps with the natural degradation of organic matter. When using aerobic digestion in sewage treatment plants, it is also necessary to ensure that the dissolved oxygen content is not less than 2ppm.

As the temperature increases, the corrosiveness of oxygen to metals increases, which can cause uneven surfaces on systems containing iron, such as high-pressure boilers and deep well oil recovery equipment. In order to prevent economic losses caused by corrosion, it is necessary to handle liquids in contact with metal surfaces, and physical and chemical methods are usually used together. The degassing method can reduce the concentration of oxygen in the boiler inlet water from a high ppm level to several ppb levels. Chemical reducing agents, such as hydrazine DEHA、 Sodium sulfite and other substances can be used as substitutes or in conjunction with degassing methods.

Indigo carmine method

Reference: ASTM D 888-87, Dissolved Oxygen in Water, Test Method A; Gilbert, T.W., Behimer, T.D., Castaneda, H.B., "Determination of Dissolved Oxygen in Natural Water and Wastewater," American Laboratory, March 1982, pp. 119-134.

The testing tool used in the fields of environment and drinking water (ppm level) adopts the indigo carmine method. The reduced form of indigo carmine reacts with dissolved oxygen to produce a blue product. The indigo carmine method is not affected by temperature, impurities, or dissolved gases (such as sulfides, which are substances that interfere with dissolved oxygen measurement), and the measurement results are expressed in ppm (mg/L) O2.

Rhodazine D™ 方法

Reference: Developed by CHEMetrics company; ASTM Power Plant Manual, 1st edition, page 169 (1984); ASTM D 5543-09， Low concentration dissolved oxygen in water, final report of NAVSECHILADIV project A-1598, evaluation of CHEMtrics boiler water dissolved oxygen test package (1975).

The measurement tools for boiler water and applications that require trace dissolved oxygen (ppb range) use the Rhodazine D method, which was developed by CHEMetrics and is a reference method recognized by ASTM for determining ppm level dissolved oxygen. In this method, the reduced form of Rhodozine D compound reacts with dissolved oxygen to produce a bright pink reaction product, which is not directly affected by temperature, impurities, or dissolved gases. Oxidants, including benzoquinone, can cause measurement results to be biased. Reducing agents, such as hydrazine and sulfite, do not cause interference.
The measurement results are expressed in ppm (mg/L) or ppb (μ g/L) O2. The low measurement range dissolved oxygen measurement tool includes a special sampling tube used for sampling boiler inlet water. This sampling tube allows the user to break the top of the reagent tube when the sample flows in, preventing interference from external oxygen gas.