What activity should be performed upon installation, at least annually thereafter, and after any major maintenance on an instrument or sensor?

• A. Siting and Exposure
• B. Calibration and standardization
• C. Maintenance
• D. Data logging

Answer: (B)

Calibration and standardization establishes the baseline accuracy of an instrument by comparing its readings to known standards and adjusting as needed. This ensures measurements stay accurate after installation, during periodic maintenance, and after any major work that could affect the sensor. By keeping the instrument aligned with traceable standards, you maintain reliable data and measurement consistency over time.

Siting and exposure relates to where the instrument is placed and its environmental conditions, which can affect readings but don’t by themselves verify or restore accuracy. Data logging is about recording results, not ensuring their correctness. Maintenance is a broader upkeep activity, but calibration specifically targets accuracy and traceability, which is why it’s the correct choice.