Molecular Sieve vs Silica Gel for moisture control?

[exgato]

I have had Molecular Sieve as a desiccant recommended to me over Silica Gel for installation between control room glass panels to absorb moisture. This from a desiccant manufacturer who seems knowledgeable and since the cost is the same for both, it doesn't seem like a sales tactic. I was told that SG was considered standard for this use but technology has changed. SG can release moisture it absorbs where as MS does not release any. Anybody using this or know if it has that advantage or if there are other disadvantages?

[Rod Gervais]

Personally, I would not be overly concered about it either way........

The possibility of your having condensation on the inside of your windows inside of a building is pretty much almost non-existent.

Think about it - first of all - the relative humidity within a building tends to want to even itself out - high pressure zones want to equalize low pressure zones.......

The next thing is that you have to have one side of the glass at a failrly drastically different temperature than the other side of the glass in order to reach dew point and have condensation take place......... again - seeing as you are dealing with interior environments here - where is that large difference going to suddenly come from - especially inside of a well insulated wall cavity......... what is suddenly going to make it heat up inside of there when both sides of the wall will have fairly constant temperature levels?

So drop in whatever you want and don' worry about it.

Now - all of that having been said - the fact that Silica Gel releases the moisture is one of the reasons that it continues to work - where-as the Molecular Sieve desiccant will reach a point where it simply stops working if it indeed works the way you believe it to. Once it reaches it's full capacity it will have to be changed........ so make very certain you have a way to access it........

Actually - a quick look at the products indicates that silica gel begins to give up moisture above 77 degrees F - whereas the MS desiccant is stable to much higher temperatures - but I can hardly see anyone keeing their room 77 - never mind higher......

Sincerely,

Rod

[exgato]

Thanks for your reply, Rod. I'm in the high desert in Southern California. Freezing nights, boiling days, extreme dryness, occasional high humidity, you name it. I've seen control room windows fog in less extreme environments. I was looking for a little insurance with the desiccant.

[Tom Boyd]

Rod, I saw a post you put up in 2008 about moisture sieves. Question? Do you know if they remove azeotropes. For instance, if I have an ethyl acetate / water azeotrope and another solvent, hexane, will the sieve take the ethyl acetate out with the water?

Thanks,
Tom Boyd

[Rod Gervais]

Originally Posted by Tom Boyd

Rod, I saw a post you put up in 2008 about moisture sieves. Question? Do you know if they remove azeotropes. For instance, if I have an ethyl acetate / water azeotrope and another solvent, hexane, will the sieve take the ethyl acetate out with the water?

Thanks,
Tom Boyd

Tom,

Interesting question - I wonder under what circumstances this might occur in a studio setting....... thus I wonder what prompted the question.

I am not a chemist - and thus have no comment to make on what may or may not work in this case...........

Rod