Which of the following is NOT a requirement for the quality of instrument air?

The requirement for instrument air includes being dry to a dew point, but the specific value can vary based on different industry standards. A dew point of 35°F is generally considered acceptable for many applications; however, it does not capture the complete range of acceptable limits or specifications that might be dictated by particular protocols.

Instrument air must indeed be filtered to a very fine standard, such as 0.01 micron, to ensure that particulate contamination does not affect sensitive instruments. Additionally, it must be free of liquids to prevent damage and malfunction in pneumatic controls and systems. Being free of hydrocarbon vapors is critical as well because these contaminants can interfere with the operation of electronic systems, contribute to corrosion, or otherwise compromise the integrity of the air used in clean environments.

Thus, while a dew point of 35°F signifies a level of dryness, it is not universally mandated or might not encompass the strictest requirements applicable in all contexts. This is what distinguishes it from the other options, forming the basis for why it is not considered an absolute requirement for instrument air quality.