Gas Viscosity at Atmospheric Pressure

The viscosity of a gas can be thought of as a measure of its resistance to flow it is usually measured in centipoises (cp).

It generally ranges from 0.01 to 0.03 cp at standard and reservoir conditions, reaching up to 0.1 cp for near-critical gas condensates.

Reference: Phase Behavior, Curtis H. Whitson and Michael R. Brule