A standard humidity system is designed to enable temporary operation down to -10°C dewpoint in a humidity chamber. A low humidity option will enable extended operation down to 5 grains of moisture per pound of dry air minimum limitation and humidity range from 5% RH to 98% RH.
The low humidity option on a humidity chamber incorporates a dry air purge for ultra low dewpoints. It also adds a bubbler humidity system which allows small amounts of moisture to be added to the air in the humidity chamber for low humidity control. This eliminates problems associated with adding hot steam to a cold environment which creates two problems: heat that needs to be taken out of the system and steam generator oscillation.