Dissolved Oxygen Meters

- Nov 06, 2018 -

The dissolved oxygen meter measures the amount of oxygen dissolved in an aqueous solution. Oxygen dissolves in the water through ambient air, air flow, and photosynthesis.


Dissolved oxygen is consumed in water by breathing and decomposition, and is mainly supplemented by air and photosynthesis. The amount of oxygen in the water depends mainly on the temperature. The oxygen concentration in warm water is lower than that in cold water. However, excessive dissolved oxygen levels can be harmful to plants and animals.


The dissolved oxygen electrode can be used to measure the dissolved oxygen content in the aqueous solution of the sample being tested in the field or in the laboratory. Since dissolved oxygen is one of the main indicators of the quality of water, the dissolved oxygen electrode can be widely used for the measurement of dissolved oxygen content in various occasions, especially aquaculture water, photosynthesis and respiration and on-site measurement. When assessing the ability of streams and lakes to support biological survival, a Biochemical Oxygen Demand Test (BOD) is performed to measure the oxygen-depleted aqueous solution containing organic matter and determine the dissolved oxygen concentration and the temperature of the sample aqueous solution. Relationship between.


TFT Touch Screen Portable Dissolved Oxygen Meters are special instruments for measuring oxygen content in liquids in boiler feed water, condensate, and environmentally friendly sewage. The dissolved oxygen electrode uses a thin film to separate the platinum cathode, the silver anode, and the electrolyte from the outside. In general, the cathode is almost in direct contact with the film. Oxygen diffuses through the membrane at a rate proportional to its partial pressure. The greater the partial pressure of oxygen, the more oxygen is transmitted through the membrane. When dissolved oxygen continuously permeates through the membrane and penetrates into the cavity, it is reduced on the cathode to generate a current, which is displayed on the meter. Since this current is directly proportional to the dissolved oxygen concentration, the calibration meter only needs to convert the measured current into a concentration unit.


The dissolved oxygen concentration is usually in mg/L (dissolved oxygen per liter of water) or ppm (parts per million). Some meters compare the calculated oxygen content to the observed concentration to give a percentage of saturation (O2% sat.)


There are two ways to determine dissolved oxygen, polarographic and galvanic. The polarographic electrode requires the input of a voltage to polarize the electrode. Since the applied voltage may take 15 minutes to stabilize, the polarographic electrode is usually preheated before use to ensure proper polarization of the electrode. The two poles of the galvanic cell type are composed of two different metals capable of generating a voltage by spontaneous polarization. Since the galvanic cell voltage is generated spontaneously rather than externally, the galvanic cell electrode does not require the "preheating" required for polarographic electrode polarization.

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