Treatment Plant Operator Exam Study Guide Answers

What factor should be considered when calibrating dissolved oxygen instruments? The answer to the question is B, barometric pressure. When calibrating a dissolved oxygen meter/probe, it is important to know the barometric pressure. Barometric pressure is directly proportional to the oxygen solubility of the water. The amount of oxygen the water can hold increases as the barometric pressure increases. You may have to manually input this reading to properly calibrate the instrument. Another fact to consider is that oxygen solubility decreases as the temperature and salinity increases. Knowing these factors may help when troubleshooting or calibration dissolved oxygen instrument. An autoclave .