Hemp me dehumidify
April 25, 2012 11:34 AM Subscribe
How can I quickly reduce relative humidity in a small enclosed environment within a fume hood without raising air temperature?
posted by Long Way To Go to Science & Nature (9 answers total) 1 user marked this as a favorite
We have a small chamber (30x30x30cm) inside a fume hood. The chamber is not gas tight, it just serves to protect the apparatus inside from the fast moving air outside (i.e. the fume hood environment). We do this because we're drying a film on glass inside the chamber and we want it to dry in still air so that it drys as evenly as possible.
Our problem is relative humidity, which we need to keep at about 25% to make good film. For safety reasons the lab has to be a single pass air system, that means that the air conditioner takes whatever air mother nature gives us does its best to heat or cool it and pumps that into the lab, then the fume hoods suck that out and dump it. It doesn't get recirculated because it contains the bad stuff from the fume hood. Thus the air handler only gets one pass at conditioning and so we have poor control of humidity within the lab. What we want is a way to aggressively remove moisture from the air within that small chamber.
Here's what we're already doing or thinking about:
Today we heat the air inside the chamber which reduces the RH, but the increased temperature also interferes with the film formation.
Typical desiccants like silica gel just don't work fast enough.
We are looking at pumping dry compressed air or dry nitrogen into the chamber.
What I would really like is a vigorous chemical reaction that strips water out of the air. We're a chemistry R&D company so we should have no problem acquiring the materials.