Best Desiccant ?
- Thread starter Mr.Gadgets
- Start date
that's confusing you know the quantity of sieve used in these filters can saturate in less than one hour at typical compressor flow rate(assuming no first stage water separator) people would replace it all the time, are you sure it doesn't lose some water when pressure decreases?
Upvote 0
While I'm as cheap/thrifty as can be I would still just buy a refill rather than trying to dry out what I have used.
Upvote 0
This thread will never die.
Here’s a link about molecular sieves.
Drying molecular sieve is near the end but I screen shot the paragraph on drying. And a screen shot from a quick google search. Not easy or practical.
www.agmcontainer.com
Unfortunately effective drying for air guns is easy. Many if not all PCP oriented compressors come with drains for first and second stages. Which is very important to the life of a molecular sieve. Water can saturate it very quickly and pass it on to guns or tanks unbeknownst
to the user.
I think the worst part of PCP’s is the dry air source required and it’s associated expense.
For someone getting into PCP’s they really need to know that and budget for drying if their chosen compressor does not come with a molecular sieve drier. YeH you can buy a bunch of pellets instead of buying a molecular sieve set up but that’s the users choice. And then there’s the airgunners that just hand pump into their guns and don’t seem to experience issues. It’s definitely a “Your Mileage May Vary” situation.
I molecular sieve dry for my PCP’s and molecular sieve dried air for scuba for 10 years in a dive shop with mandatory air analysis for several impurities and moisture and never ever failed to qualify for Grade E breathing air which is the recommended air standard by most airgun manufacturers.
Unfortunately I don’t think there’s a simple way of determining moisture content without sending a sample for analysis which of course costs money to perform.
If your guns run fine on wet air, awesome
I just prefer to use dry air. My hobby is for fin and enjoyment. If I want aggravation, I’ll go back to work.
Here’s a link about molecular sieves.
Drying molecular sieve is near the end but I screen shot the paragraph on drying. And a screen shot from a quick google search. Not easy or practical.
All About Molecular Sieve Desiccants
Molecular sieve removes moisture from air and other gas streams, and can selectively capture various molecules, such as VOCs, making it a highly capable desiccant.
www.agmcontainer.com Unfortunately effective drying for air guns is easy. Many if not all PCP oriented compressors come with drains for first and second stages. Which is very important to the life of a molecular sieve. Water can saturate it very quickly and pass it on to guns or tanks unbeknownst
to the user.
I think the worst part of PCP’s is the dry air source required and it’s associated expense.
For someone getting into PCP’s they really need to know that and budget for drying if their chosen compressor does not come with a molecular sieve drier. YeH you can buy a bunch of pellets instead of buying a molecular sieve set up but that’s the users choice. And then there’s the airgunners that just hand pump into their guns and don’t seem to experience issues. It’s definitely a “Your Mileage May Vary” situation.
I molecular sieve dry for my PCP’s and molecular sieve dried air for scuba for 10 years in a dive shop with mandatory air analysis for several impurities and moisture and never ever failed to qualify for Grade E breathing air which is the recommended air standard by most airgun manufacturers.
Unfortunately I don’t think there’s a simple way of determining moisture content without sending a sample for analysis which of course costs money to perform.
If your guns run fine on wet air, awesome
I just prefer to use dry air. My hobby is for fin and enjoyment. If I want aggravation, I’ll go back to work.
Upvote 0
Generally desiccant first, then carbon.Carbon is actually pointless for a pcp rifle, it removes odors. It's more for air that will be breathed.
Upvote 0
Yes. If you purchase a pre-assembled cartridge for a molecular sieve it will have a specific orientation. Typically the beads see the air first, the there’s a filter pad for any dust off the beads, then charcoal for odor from oils if present and then another filter pad.
I linked the Alkin packing video. Ayden refers to the off white colored disks as gaskets but technically they’re felt filters.
Some people don’t use charcoal if not for breathing air. In that case you add additional molecular sieve because the cartridge should be completely full.
There are companies that sell a pre-assembled filter that drops right into the HP chamber which completely replaces the aluminum can that was filled in the video. Pre-assembled (packed) cartridges are a bit more expensive but make the job super simple.
Upvote 0
Make sure that you use something like those cartridges to prevent the molecular sieve from having direct contact with the aluminum pressure vessel, as molecular sieve leeches acid when it absorbs moisture, and can degrade the aluminum.
Upvote 0
@stephenst4470 please share a third-party source beside a singular retailer to substantiate this claim. I've done online research and have never been able to find information to verify the claim that direct contact with molecular sieve will acid leech filter walls causing a failure. Nor can I find outside data that shows an owner repacked filter allows moist air to bypass the media in the filter even under pressure. There have been a minimal number of exploding Chinese filter posts which were not claimed to be caused by media leeching. Both were claims of inferior construction quality failures under pressure. They were not claims of acid leeching filter failures.
Alkin repackable cartridges are made of aluminum. Alkin's Youtube video posted in this thread shows molecular sieve repacked in contact with the aluminum filter walls. A compressor user would have to neglect using the water separator tower drains and not replace molecular sieve in a filter for a very long time to even possibly create saturated media. On an Alkin the repackable filter is inside of a housing which is several times thicker than the aluminum filter cartridge. If someone repacks their own filter and replaces media on a manufacturer's suggested schedule there is zero corrosion from aluminum contacting molecular sieve. For example, my repackable cartridge is four years old with 12 hours of run time and a recent check revealed the media and filter walls to be as dry as a bone.
Last edited:
Upvote 0
If I’m not mistaken, Joe Brancato states that you should not leave a molecular sieve laying horizontal.
Upvote 0
any links to a drain tee or valve? my tuxing is the poor version without any filters, i was thinking of using this mod to cool and condense air before the second stage but i reckon water would drip back to first stage so not sure what to do
the sieve/acid discussion is interesting I've also not found anything to back it up though chemistry is not my strength i guess a pet/cotton wrap wouldn't hurt on thin chinese casings
as for coolant i see organic/inorganic options any difference between them?
the sieve/acid discussion is interesting I've also not found anything to back it up though chemistry is not my strength i guess a pet/cotton wrap wouldn't hurt on thin chinese casings
as for coolant i see organic/inorganic options any difference between them?
Last edited:
Upvote 0
If you are worried about it ,get some clear report covers from a local store and cut to size.. Roll it up and place that in the filter before adding desiccant..
Upvote 0
I don't really have anything for a reliable source for that info, I just saw several posts regarding it, and a filter vendor mentioned it in a YouTube video that I saw. I don't really have anything to back that up, just random posts that I saw like you did. I remember seeing one thread that implied that a filter explosion that caused a pretty severe hand injury was caused by thread failure on the end caps due to acid leeching. After that I just figured it's better to err on the side of caution, as I'm not a chemist. It didn't make a lot of sense to me either when I saw it, as acid damage to the anodizing on the filter wall should be pretty visibly evident before it would cause a pressure failure in an 8mm wall, but again, that pressure always makes me a little nervous anyway. I've been a diver for decades, and the culture with dive bottles was always filling them in a tub of water with a cage over the top, so this whole nonchalant attitude with filling pressure vessels to 300+ bar in our own garages is still something I'm adjusting to. On the upside, I've never personally witnessed a pressure vessel failure other than when helping out with hydros, where it was pressurized to two and a half times it's rated pressure and safely contained in a cement tube and water.
Last edited:
Upvote 0
I think that really only pertains to extending the life of the media, and having it upright is more likely to let the condensate drain back to the water release on the compressor instead of saturating the media. I don't think it causes any type of safety issue.
Upvote 0
When gold filters first became popular I made up some "roll your own" desiccant cartridges for them using clear transparent projector sheets. Tuxing and others soon came out with high quality repackable filter cartridges which made aftermarket ones unnecessary. I had one of the earlier version filters and never had any corrosion since the filter was anodized inside and out. It was used on a Daystate compressor that had an effective water separator. A compressor needs an effective water separator tower before the desiccant filter to remove 99% of the moisture. If water is collecting at the base of the desiccant tower the desiccant will be saturated in a short period of runtime. Desiccant is supposed to remove the last percentage of moisture the water separator doesn't remove.
Last edited:
Upvote 0
Here is Air Tanks For Sale info on the “acid” mention. Read the info in the DESCRIPTION portion pretty much to the end. I also added a screen shot of the pertinent portion of the “acid” mention.
I also linked the Air Tanks For Sale (Joe Brancato) video where he explains vertical and acid leaching.
www.topgun-airguns.com
I also linked the Air Tanks For Sale (Joe Brancato) video where he explains vertical and acid leaching.
Pre-Order Alpha In-Line Moisture Filter – Sept 7, 2024
When Filling a PCP airgun or air tank from a Yong Heng, Shoebox, Alpha, Omega (or similar high pressure compressor without a true water separator AND air filter), a quality in-line moisture filter should be used to remove all oil, water and particulates from the air. This is an absolute must to...
www.topgun-airguns.com Upvote 0
@rcs9250 when I was replying to a previous post in this thread I didn't refer to the retailer by name. Your post refers to that retailer who is a biased source. I am asking for actual third party references that verify issues of molecular sieve corroding aluminum and air channeling past molecular sieve that is repacked by an individual. This retailer sold owner repackable black filter cartridges from Carette compressors and they sell Alkin compressors which use aluminum filter cartridges. This contradicts the warnings from their own videos.
Last edited:
Upvote 0
I’m going to do some research and contact a few third party sources and see what is learned and post it shortly.
Extremely busy with some gun club projects at the moment but will post soon hopefully.
Upvote 0