The pictured molecular sieve drier came from Joe Brancato, it’s his Alpha filter with some modifications.
The filter came with bleed valves, pressure gauge, high pressure line, the filter drier itself and a PMV ( pressure maintaining valve).
I did a lot of work in the scuba industry with compressors and air storage to 6,000 psi. Any compressor, from home shop/garage up to scuba type compressors draw in moisture laden ambient air and compresses it to your desired pressure. While hot, the moisture is in suspension just like on a hot humid day, and just like in nature, as the day cools the air can no longer hold that humidity and it drops out as condensate (water) as you see it on the grass or your car windshield and body sheet metal. In a compressor with no way of removing moisture this can occur in your guns air tank or in its internals.
Anyway, I modified it by mounting it to a bracket and bolted it to my compressor table as it must ALWAYS stay vertical. A molecular sieve must also stay pressurized after initial pressurizing at 1,700psi, that’s the purpose of the pressure maintaining valve, it will not let air out of the drier vessel until it exceeds 1,700psi. I added to scuba line valves (black knobs in photo) to assure that when the unit is not being used I can close the input and outputs of the filter just as extra measure to make sure I don’t lose pressure in sieve. On a low cubic foot per minute output compressor like the ones we use for air guns, we don’t want to waste time re-compressing air un-necessarily, hence valves in addition to the PMV. The sieve must stay pressurized so the moisture that’s been absorbed by the sieve beads doesn’t condensate out, becoming water and potentially turning to steam as a result of an exothermic reaction and potentially blowing up the filter.
I also redesigned the air input to the filter so it comes in from above the bottom of the sieve so that when you occasionally drain off small amounts of moisture from the sieve it goes down into the drip leg. Draining condensate on the compressor and the sieve is a requirement. Some compressors have an automatic drain cycle that lasts one or two seconds to take care of condensate accumulation.
The Alpha filter is $400 and I added another hundred or so to the project in valves. Maybe the whole drier is overkill but I’m getting the same dry air that I would be getting if I went to a dive shop, which in my area is max 3,442psi which really sucks having a 4,500 psi scba tank. And in addition, they require yearly tank inspection which takes two or three weeks and $40, not to mention the inconvenience of having to go to the dive shop and leave the tank for a couple days for the fill, then a return trip for a 3,442psi fill. I’m happy with my set up. Compressed air is never cheap.
See photo of my Omega Air Charger and filter set up.
