Molecular sieve use and storage?

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Eaglebeak

Eaglebeak

Member
Aug 21, 2017
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Victoria, Australia
Can anybody with experience with this stuff, answer a few queries I have regarding its use? I have been told it can be reactivated by heating to 200 degrees C but this is useless as it rehumidifies whilst it cools. Would it be possible to seal it in a container straight from the oven and let it cool in an airtight storage vessel? I have 500 gram of this stuff but I only want to use about 100 grams at a time. Will the whole batch spoil after I open it or can it be resealed before it sucks up the surrounding humidity? Also, how will I know when it is saturated and due to be swapped out? I don't think it has a dye in it like silica gel. 
Regards
Ian
 
I deal with it on a large scale purifying nitrogen, air and methane.
I don't think that you have to worry as much as sealing it right after it hits top temperature. All sieves behave different. Generally when they hit a target regen temperature they dry quickly. I'm guessing you are doing the regeneration process in a kitchen oven?? You may open the door a crack to release any moisture for several minutes at top temperature. A lot of "air dryers" rely on a fast release of pressure to help release moisture from sieve as well, but heat is generally best. Again sieve is all designed differently for different applications.
Keep in mind as soon as you expose it to compressed air it will start to be on a path to saturation. When we add sieve or it sits it is immediately heat regenerated before use. We also give it a positive purge of dry nitrogen to keep it from saturation when sitting for a longer period of time. Your correct it needs to be stored sealed. Perhaps you could use a food vacuum bag or the food vacuum canisters they sell.
I actually bring my compressor to work to take advantage of our dry air to fill bottles.
 
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I once had an ozone generator that was used In my saltwater aquarium hobby it used molecular sieve material to pre dry the air there was a color changing beads mixed in with it that went from blue to pink when moist. I would put them in a shallow pan in a 200 degree oven and when the turned blue I would pour them into a heavy doubled zip lock bag, I rotated them this way for years without a problem.
 
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"Eaglebeak"Can anybody with experience with this stuff, answer a few queries I have regarding its use? I have been told it can be reactivated by heating to 200 degrees C but this is useless as it rehumidifies whilst it cools. Would it be possible to seal it in a container straight from the oven and let it cool in an airtight storage vessel? I have 500 gram of this stuff but I only want to use about 100 grams at a time. Will the whole batch spoil after I open it or can it be resealed before it sucks up the surrounding humidity? Also, how will I know when it is saturated and due to be swapped out? I don't think it has a dye in it like silica gel. 
Regards
Ian
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i dont think there is any point using that stuff. 500gram 100 gram... too little to trap moisture, if you want to run thousands of liters of moist air through it. what i am saying it you saturate it very quickly (depends on climate) 
the parts affected by corrosion in a pcp will costs less than the whole moisure trap kit. 

plus i would be concrned about the dust it releases to the system. i know activated alumina does this. other porous material too needs extra frits to stop it too.
 
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I can think of no technical reason not to do what you are proposing. In fact, its a pretty good idea IMHO. Probably 5% would do fine, just enough to see if there is a color change. The Zeolite 13X is normally fairly light beige in color and darkens as it absorbs moisture. When you open up the filter after ten run hours or so, compare the color to the color of your unused (sealed) beads. 
 
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The whole point of vacuum is that water will boil at a very low temp. 29.92 inches of vacuum. Water will boil at -90degrees farenheight. Water will turn into vapor. Water is made of h and oxygen. Thus sucking all the water out. In a.c. systems it is necessary to remove all moisture in the system for longevity. The a.c. pumps and oil do not like water which will cause premature failure. Such a technique is used to remove moisture of the system. In a perfect a vacuumed hydrogen and oxygen will not exist. Most silica when opening has a vacuum to it from the beginning so that it doesn't get saturated with moisture. It is a proven method to remove moisture in systems but it all depends on the silica. Some silica will not release moisture once it has absorbed it. That is where I am not sure if it will work. The systems where people bake to remove moisture, a vacuum system will work. But the hill pump style with silica beads not sure. Does anyone know if it is the same material?
 
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I use the color changing desiccant stuff in a homemade drier I made for my argon gas setup that I use with my TIG welder, as a little moisture can destroy an otherwise good weld. I don't use it for my PCP stuff, it doesn't really matter if there is a little moisture in the air. I buy the blue crystal desiccant by the kilogram in China. It's pretty cheap. My drier is made from a clear Plexiglas tube. I machined the end caps to use "O" rings and 1/4" NPT fittings. The inside of the caps use 1/4" NPT muffler fittings (metallic foam) to separate the crystals from the argon. The same could be used on a compressor intake line. The advantage is that the crystals change color from blue to pink when saturated. The crystals can be reused by baking in the oven at 300F for about two hours or until again blue. After baking the crystals dry (blue), just put them in a sealed plastic bag ready for reuse. As long as the bag is kept sealed, the crystals can be kept indefinitely. There is a max baking temperature that I believe is about 350F. Above which the desiccant is destroyed. Just as a note, my drier is 2.250" in diameter and is 11 inches long. It holds about 500 grams of desiccant.
 
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Been using the Diablo air dryer from AoA in my AV compressor and so far it is still dry, 4.5 hours on it. Just took it apart and it has the beads that look like what is in the Hill pumps but larger and also had some of the color changing beads too. That is how I know the stuff is still dry, it is still dark blue.



I got a gallon of the color changing stuff of amazon, I think. I dry the color changing bead on my stove, placed on the smallest burner with lowest heat. My stove is kinda fancy so it has a burner that has a middle flame that is not much more then a pilot light...kinda cool seeing it slowly changing colors.
 
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I use the color changing desiccant stuff in a homemade drier I made for my argon gas setup that I use with my TIG welder, as a little moisture can destroy an otherwise good weld. I don't use it for my PCP stuff, it doesn't really matter if there is a little moisture in the air. I buy the blue crystal desiccant by the kilogram in China. It's pretty cheap. My drier is made from a clear Plexiglas tube. I machined the end caps to use "O" rings and 1/4" NPT fittings. The inside of the caps use 1/4" NPT muffler fittings (metallic foam) to separate the crystals from the argon. The same could be used on a compressor intake line. The advantage is that the crystals change color from blue to pink when saturated. The crystals can be reused by baking in the oven at 300F for about two hours or until again blue. After baking the crystals dry (blue), just put them in a sealed plastic bag ready for reuse. As long as the bag is kept sealed, the crystals can be kept indefinitely. There is a max baking temperature that I believe is about 350F. Above which the desiccant is destroyed. Just as a note, my drier is 2.250" in diameter and is 11 inches long. It holds about 500 grams of desiccant.
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Never heard of anyone use a moisture absorber for thier shielding gas...
 
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Been welding for 45 years and bottled argon gas is moisture free.

I HAVE seen MIG/GMAW welding leads full of water (condensation for some reason) and as the wire feeds it gets wet and produces crappy welds. I have also seen wire that the copper plating has rusted and the rust ( Fe + Di-Hydrogen Oxide) on the wire causes contamination.

However, some metals have some porosity and I have seen some carbon steels welds fail from it. Appropriately preheating the metal drives off the water and the weld is fine (of course, that depends on the skill of the welder and all the other preparation needed, bevel, amps, surface cleanliness, etc)

SMAW - Rod/stick flux (ex: 7018 Lo-Hydrogen rod) is notoriously water absorbent and welding code requires it to be baked in an oven to drive off the water... of course you do not use argon with that method, haha.



I use regular silica Gel blue beads in a 1-1/4 clear PVC tube 24" long which feeds by flex hose into my compressor intake then after the compressor a water trap followed by 13x molecular sieve in a gold filter housing for the HPA (the sieve is in a plastic folder cover cut to be a tube with a fiber plug at each end to retain it and keep dust from entering the discharge). I reactivate it in an electric oven and seal the extra in seal-a-meal bags.

I also cap both the intake dryer and plug the exhaust quick connect coupling to prevent atmospheric moisture from deactivating them between tank or rifle fills.


 
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I use the color changing desiccant stuff in a homemade drier I made for my argon gas setup that I use with my TIG welder, as a little moisture can destroy an otherwise good weld. I don't use it for my PCP stuff, it doesn't really matter if there is a little moisture in the air. I buy the blue crystal desiccant by the kilogram in China. It's pretty cheap. My drier is made from a clear Plexiglas tube. I machined the end caps to use "O" rings and 1/4" NPT fittings. The inside of the caps use 1/4" NPT muffler fittings (metallic foam) to separate the crystals from the argon. The same could be used on a compressor intake line. The advantage is that the crystals change color from blue to pink when saturated. The crystals can be reused by baking in the oven at 300F for about two hours or until again blue. After baking the crystals dry (blue), just put them in a sealed plastic bag ready for reuse. As long as the bag is kept sealed, the crystals can be kept indefinitely. There is a max baking temperature that I believe is about 350F. Above which the desiccant is destroyed. Just as a note, my drier is 2.250" in diameter and is 11 inches long. It holds about 500 grams of desiccant.
Click to expand...

Never heard of anyone use a moisture absorber for thier shielding gas...
Click to expand...

Ask Jodie on "Welding Tips & Tricks" forum. He uses an Argon moisture trap as well.
 
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