rjack, do you have a published source for this or was it calculated independently? I was not aware that CGA grade E specified a pressure level which correllates with the moisture limit. However, the Europeans have dual moisture requirements under EN12201 which depend on final cylinder pressure and but I'm not up to date on this; I wonder about the current specific level specified for 200 bar, eg if they have actually lowered the volumetric humidity to the level of 20 mg/m3 @ 200 bar and 15 mg/m3 @ >200 bar as they were planning to do. These levels would be equivalent to 20% RH at 200 bar and 300 bar respectively at temp of about 24C. Furthermore, the numbers should be equivalent to dew point of about 0 C at the respective pressures. That is the point, really, to restrict condensation in cylinders of high and very high pressure ratings to fairly low ambient temps.