Dug out a copy of ANSI/ISA 7.0.01-1996 "Quality Standard for Instrument Air". Could not find a reference to my previous statement that dew poit should be -60 to -70C for this standard. I have used that temperature but that is for colder climates than yours. What is stated "The pressure dew point as measured at the dryer outlet shall be at least 10C(18F) below the minimum temperature to which any part of the instrument air system is exposed. The pressure dew point shall not exceede 4C (39F) at line pressure..." Futher : Definition-pressure dew point "The dew point safty valve at line pressure of the compressed air system (usually measured at the outlet of the dryer system or at any instrument air supply source prior to pressure reduction. When presenting or referencing dew point, the value shall be given in terms of the line pressure.." In addition to what has been stated in previous replies, I recall years ago that warmer climates would have problems with mold. That has aparently diminished some now I suppose with fungal sprays to the electronics. In summary one would have to look at the coldest IA user in the plant and insure that the dew point meets the criteria.

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