The instrument air dew point high alarm will indicate on master alarm panels when the line pressure dew point exceeds what temperature?

• A. -22ºF
• B. -44ºF
• C. -32ºF
• D. -39ºF

Answer: (A)

Dew point is the temperature at which moisture in the air would start to condense. In instrument air systems, keeping the dew point low means drier air and less risk of condensation that can affect pneumatic instruments and valves. A high dew point on the line indicates moisture is increasing, so a master alarm is set to trigger when the line pressure dew point rises above a designated limit, prompting inspection of dryers, filters, or leaks.

The value -22°F is a practical, commonly used threshold for instrument air—the air is still dry enough to protect pneumatic devices, while not being so restrictive that the system becomes unnecessarily energy-hungry or costly. Other options would imply even drier air or are less typical as a general instrument-air alarm setting, so -22°F best fits standard practice for triggering the high alarm.