Calibration Method And Maintenance Of Dissolved Oxygen Meter

- Oct 25, 2017 -

Dissolved oxygen analyzer is a polarographic analysis instrument, specially designed for ppb level dissolved oxygen measurement of boiler feed water and condensate water. It ensures the stability and accuracy of (ultra) low concentration, and greatly improves the measurement performance and environment. Dissolved oxygen meter is mainly used for continuous monitoring of dissolved oxygen in chemical fertilizer, metallurgy, environmental protection, pharmaceutical, biochemical, food and tap water.

Dissolved oxygen meter has the advantages of convenient installation, calibration period (3~4 months), the other is not sensitive to material characteristics, and to use the monitoring probe coating and electrolytes in general, every one to three years to replace a film and electrolyte. Generally, the dissolved oxygen analyzer can be calibrated by standard liquid or by field sampling. Calibration method of standard solution for dissolved oxygen meter: calibration of standard solution usually adopts two points calibration, that is zero calibration and range calibration.  Zero calibration solution can use 2% Na2SO3 solution. The range calibration solution can select 4 M of KCl solution (2 mg/L) and 50% methanol solution (21.9 mg/L) according to the measuring range of the instrument. Field calibration method (Winkler): in the actual use of dissolved oxygen meter, Winkler method is used to calibrate the dissolved oxygen analyzer. Use this method when there are two: the sampling instrument readings for the M1 analysis value is A, calibrating the meter when the meter reading is M1, then only the meter reading can be equal to A; when sampling the meter reading M1, laboratory analysis of calibration value is A, when the meter reading is M2 to change this will not be able to adjust the instrument, meter reading is equal to A, and should be adjusted to 1MA * M2 readings.

The electrode of the dissolved oxygen instrument should be cleaned once 1~2 weeks in the maintenance of the electrode of the dissolved oxygen instrument. If there is contamination on the diaphragm, the measurement error will be caused. Cleaning should be careful, pay attention not to damage the diaphragm. The electrode dissolved oxygen meter in water washing, such as dirt can not wash, carefully scrub with a soft cloth or cotton. The zero and range of the electrode of the dissolved oxygen instrument should be checked again in 2~3 months. The regeneration of the electrode of the dissolved oxygen analyzer is about 1 years. When the measuring range is not adjusted, the regeneration of dissolved oxygen electrode is needed. Electrode regeneration includes replacement of internal electrolyte, replacement of membrane and cleaning of silver electrode. If the silver electrode is oxidized, fine sand paper can be used to polish it. In use, if the electrode leakage of dissolved oxygen instrument is found, the electrolyte must be replaced. Refer to the above said, the use of dissolved oxygen meter to buy back is not to be used correctly, it is important to maintain, there are a lot of customers do not use the buy back in after there is a problem, is the most technical personnel when taking electrode accidentally ran into the film first broke the film, so as a result of customers and suppliers over the negotiations and turnover of repair, therefore, can do regular care when in use, will avoid a lot of unnecessary trouble.

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