A brand new glove box has been received. All the inside equipment was baked for several hours and I also tried to increase the blowing rate to renew the atmosphere faster. I know that the last few ppm require higher and higher gas volume to be removed, but the moisture level remain stable around 3 – 4 ppm for few days now. Have you any suggestion to lower the moisture concentration? Does silica desiccant gel could help?
I precise that the copper catalyst colon has been regenerated a first time.
Thank you for your help
Sincerely
Youn,
Two systems are typically used to minimize humidity in Glove Boxes, (i) Desiccant Drying and (ii) Dry Gas Purge. Although desiccant drying systems are standard, Dry Gas Purging will typically attain lower moisture residues. Gas Purge also allows for faster drying times and requires less maintenance. Desiccants need to be rejuvenated / replaced and are considered a “cleaner” process. Desiccant drying can also be a lot less expensive to operate. Finally, both systems can also be used in tandem to minimize the cost of lowering moisture levels in the glove box.
Regards
Steve
Dear Youn,
If you have just received it and brought a lot of stuff inside, it is possible that it will simply require even more time. As Steve A. Carr mentioned above, purging the box with dry gas should help speed that up.
Anyway here are some issues that I encountered that could affect the O2 and moisture level in a glove box:
Firstly, the source of your inert gas, if it is more than just one tank, then maybe check with the supplier to see what specifications they actually guarantee.
Second, the line running form your gas tank to the box, if there is a leak somewhere, this could in theory lead to some contamination although the line should have a higher pressure than the surrounding air.
Thirdly, the boy itself could have a leak, maybe something was overlooked during the assembly, some feedthrough is not properly tightened or one of the gloves has some minor damage. The room temperature of the lab can also affect the sealing of the box, I have had a case when at low room temperature (< 20 °C) O2 and moisture levels increase because the rubber seals become too hard and don’t seal as well anymore. To mitigate problems like that you might want to use a higher working pressure inside the box.
Another source of introducing moisture and O2 is the process through which you bring all your things inside, we usually used 3-4 cycles of 15 min under vacuum in a small antechamber (airlock) or one overnight cycle on a large antechamber. The things you take inside should be as hot as possible when you put them in the chamber (you already mentioned that you baked everything so I guess that is not your problem). Avoid things like paper tissues or any kind of textile fabric and anything with a large surface area if you can.
I would also suggest that you keep the antechamber under vacuum when it is not in use.
Since you mentioned that you already regenerated the catalyst I assume that this is not the problem but I have had instances where the regeneration was unsuccessful due to insufficient regeneration gas flow rate. If you are in doubt about that you can repeat the regeneration with a higher gas flow rate.
A last point I can think of is the sensor itself. If you turned it on to early it might have been contaminated with moisture/O2 and might require cleaning to function properly again. Check the maintenance manual for that.
I hope one of these suggestions can help you to find the problem.
All the best
Max
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