Application Note: Why Use Nitrogen To Purge Moisture In Desiccators?

Nitrogen is the standard medium for contamination-free storage because it is relatively inert—it neither reacts with stored materials nor carries moisture—and because it can be isolated and purified relatively inexpensively.

Desiccator cabinets must be set up so that an appropriate flow of nitrogen forces out all moisture- and contamination-laden air. Because nitrogen has a lower specific gravity than air, it is introduced into the upper section of the desiccator; the heavier air is then purged out of the bottom.

Failure to maintain the appropriate nitrogen flow into a desiccator, or to bleed the cabinet effectively, can be devastating. Once inside a desiccator, moisture can penetrate the molecular structure of stored components, requiring baking or vacuum processing.

These application variables point to the need for an efficient humidity control system. When doors are frequently accessed, a smart purge controller will deliver a high flow to the affected chambers, and multiple bleed valves will allow moisture to exit before it can migrate to other chambers.