The DO correction is the same as the pH correction, using the 2-point correction method.

DO is generally calibrated 100% in the air, and the correction of DO electrode refers to sterilization during the fermentation process, and 100% is corrected at the maximum ventilation and stirring volume required for fermentation.

The polarographic DO electrode can be calibrated to 0% in saturated anhydrous sodium sulfite solution（Coca Cola with gas is best）, and the optical dissolved oxygen electrode does not need to be calibrated to 0%. The zero offset can be checked with carbonated beverages, and it should be cleaned after calibration.

The definition of DO is the absolute value concentration of oxygen dissolved in water, which is generally calibrated under normal pressure, so the oxygen concentration is about 21% at this time, and the air concentration is 100%. The absolute amount of oxygen is converted to 100%. If the tank pressure increases to 0.05MPa during the fermentation process, which is equivalent to a 50% increase in pressure, the corresponding absolute value of oxygen concentration will increase by 50%. Therefore, the corresponding DO The maximum value will reach 150%; when the tank pressure reaches 0.1MPa, the full scale dissolved oxygen value will be 200%.

Normal calibration is 100%.

Wash and dry after use.