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So if you do everything right, how low of a dew point can you get using 13x for a dessicant? How do you do everything right?
Does this link help? https://airanalysis.com/Moisture_In_SCUBA___SCBA.html
and this: https://www.sorbentsystems.com/desiccants_charts.html
How do you do everything right ???
Why nobody took on that part I have no idea, but here you go.
Lots of debate on how you get there...but one fundamental across the board fact, dwell time.
The amount of time the air is in contact with the adsorbent. More time, more moisture is removed.
I can imagine, though have no way to prove that molecular sieve could if given time, get air very, very close to 0 ppm moisture content. It is tenacious in its desire to grab and hold water molecules. It has to be heated to 500* to get it to release the moisture it has trapped.
Slow the flow rate though the filters as is done in hyperfiltration, to produce oxygen compatible air (Though this is more often then then not done to address micro particles of oil then water...flow rate is usually is controlled by a jewel with a laser drilled orifice that will allow a certain amount of air past at a given pressure.
Up size the existing filtration if there is any question of capacity and keep the filters pressurized at all times, even when not in use.
PMV. Pressure maintaining valve, to stop air from flowing through the filters at low pressure and high speed....(As in when you connect a near empty cylinder... set at as high a value as your system will allow, this will increase dwell time...is an absolute must have item..lack of one or its failure, and you will be pumping water and all manner of crap into your tanks in short order. I have pressure gauges before and after mine so I KNOW it is working. When it cracks open, the upside gauge drops and the downside gauge starts to rise. I fill direct to my tanks, and keep my filter pressure 190 BAR, normal is 140-150 BAR.
You will likely not be able to do this unless you are pumping into H.P. banks, but if you do as I do, you can get that high pressure..PMV located after the last filter...with OPV at separator...set to open at about 250 Bar, thus keeping the filters at 180 bar (There is some slack in the PMV. it will first crack at about 250 BAR, then drop to its maintaining pressure, Usually around 50-70 BAR less ...then at the whip manifold ANOTHER OPV set to 210 bar. This way you get high filter pressure, but no need to worry about over filling your 200 bar tanks.