Final line filters for instrument air shall be equipped with a ______ visual indicator showing the status of the filter element life.

• A. continuous
• B. alternating
• C. pulsating
• D. optional

Answer: (A)

A continuous visual indicator is essential because final line filters in instrument air require constant, reliable feedback on filter element life. With a continuous indicator, the status is always visible, reducing the chance that a worn-out filter is overlooked in a busy clinical environment and helping ensure the air used by medical devices remains clean and dry. The other options are less practical: alternating or pulsating indicators can be easy to ignore or misread during emergencies, and optional implies the feature isn’t required, which isn’t suitable for safety-critical instrument air systems.