What Is a Dry Room?
Any manufacturer of moisture sensitive or hygroscopic products can often realize substantial productivity increases in an economical way by utilizing a dry room, Lithium battery manufacturers, pharmaceutical diagnostic firms and other firms have all been using dry rooms successfully for many years.
The critical variables from which dry room design begins are:
• The specified temperature and humidity control level.
• The number of people operating in the room.
• The number of times the room will be breached, such as entries and exits by the personnel.
• The room exhaust or loss due to openings.
• The make up air amount and conditions.
• Vapor Transmission- Permeance through the perimeter
The control level and the personnel moisture load in the space dictate the requirements for the size of the dehumidification air handling system required to maintain the room at specifications. With careful design, desiccant dehumidification systems capable of delivering air to a minimum of .47 gr/lb. (-76ºF. dewpoint, 10.6 ppmv) can be integrated into the dry room construction thereby allowing room operating levels as low as 1/2% R.H. to be maintained.
Location of the desiccant drying system in as close proximity as possible to the dry room, reduces the possibility of moisture infiltration into the conditioning system, and eliminates long runs of ductwork. If this design cannot be utilized, dehumidification systems can be skid mounted and located above the dry room inside the main building or a rooftop D/H skid can be constructed.
The room structure and layout are best depicted in the illustration below which shows a typical production dry room with two D/H series systems.