What should be documented during calibration of a DO probe?

What should be documented during calibration of a DO probe?

• A. Temperature, zero/air-saturation reference values, and calibration date.
• B. Only the instrument serial number.
• C. The color of the sample.
• D. The last maintenance technician.

Answer: (A)

The key idea is that a DO probe’s calibration needs to be documented with the conditions and reference points used so the measurement is meaningful and repeatable. Temperature matters because the amount of dissolved oxygen in water depends on temperature; the calibration should reflect the actual temperature at the time of calibration so the instrument can apply the correct temperature compensation and produce accurate readings. Recording the zero or air-saturation reference values shows exactly which reference points were used to set the sensor’s baseline and full-scale, ensuring the instrument is calibrated against known standards and that you can reproduce or verify the calibration later. Logging the calibration date creates a traceable record, helping you enforce calibration intervals and verify when the instrument was last checked. Other details like the instrument’s serial number or the sample color aren’t part of the calibration record itself, and noting the last maintenance technician isn’t essential to the calibration data, though it may appear in a broader maintenance log. The essential documentation for calibration is the temperature, the reference values (zero/air-saturation) used, and the calibration date.

The key idea is that a DO probe’s calibration needs to be documented with the conditions and reference points used so the measurement is meaningful and repeatable. Temperature matters because the amount of dissolved oxygen in water depends on temperature; the calibration should reflect the actual temperature at the time of calibration so the instrument can apply the correct temperature compensation and produce accurate readings. Recording the zero or air-saturation reference values shows exactly which reference points were used to set the sensor’s baseline and full-scale, ensuring the instrument is calibrated against known standards and that you can reproduce or verify the calibration later. Logging the calibration date creates a traceable record, helping you enforce calibration intervals and verify when the instrument was last checked.

Other details like the instrument’s serial number or the sample color aren’t part of the calibration record itself, and noting the last maintenance technician isn’t essential to the calibration data, though it may appear in a broader maintenance log. The essential documentation for calibration is the temperature, the reference values (zero/air-saturation) used, and the calibration date.