Desiccators in the Cleanroom: What are the Options? Part 1

Desiccators in cleanrooms are usually glass jars used to store pre-dried samples of hygroscopic chemical reagent. They’re sometimes also used to cool substances that were heated in a beaker. In a laboratory, they are very useful, but in a cleanroom, they can be a contamination hazard.

One of the primary issues with glass desiccators is that cleanrooms usually require very precise humidity controls. The devices manufactured in semiconductor, medical device, and pharmaceutical cleanrooms are moisture-sensitive devices (MSDs). The desiccators cannot maintain these extremely low levels of relative humidity.

Desiccators create a drying effect through adsorption using a desiccant powder like calcium chloride or silica gel on the bottom. The sample sits on a small platform, and the jar is sealed using silicone grease. Once this system reaches its saturation point, it can’t provide moisture protection. Saturation is visible when the powder changes color from blue to pink. To return to its adsorptive abilities, the desiccant has to be regenerated through a 24-hour heating cycle to bake out the moisture.

At this point, the desiccator has to be manually handled. This is both disruptive to processing and poses a risk of contamination. In any case, these jars generally provide insufficient drying.

The vacuum desiccators will effectively dry samples that can withstand the vacuum environment. However, the entire system brings noise and contaminants to a cleanroom.

These options are clearly very poor for cleanroom applications. In our next article, we will look at the alternative that desiccant-based dry cabinets provide. If you need cleanroom validation or certification, talk to Gerbig Engineering Company. We have tried and thorough expert services: 888-628-0056info@gerbig.com

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