The instrument shown in the illustration has not been used for several weeks. Prior to its use for testing a compartment, you should __________. Illustration SF-0003

Correct Answer: Option D — all of the above

Proper maintenance of gas detection equipment is vital for safety. Before use, the operator must verify battery voltage, purge the sampling lines of residual gases, and zero the meter in fresh air. These steps ensure the instrument provides accurate, reliable readings, preventing false negatives when testing potentially hazardous confined spaces.