Dry gas – Is any gas or gas mixture that contains no water vapor and/or in which all the constituents are substantially above their respective saturated vapor pressures at the existing temperature. In commercial compressor work a gas may be considered dry (even though it contains water vapor) if its dew point is low at the inlet condition (say −50ºF to −60ºF / -45ºC to -51ºC). In commercial compressor work a gas may be considered dry (even though it contains water vapor) if its dew point is low at the inlet condition (say −50ºF to −60ºF / -45ºC to -51ºC).