Personally, I wouldn’t buy squat from JB, but this guy made sense;
LOL ... you guys are making this too hard. Who cares what the dew point is as long as you are doing your best to remove as much moisture as you can?
ANY compressor is going to be able to compress the air. And, since water or oil isn't compressible, it becomes a bigger "chunk" of the air that gets pumped out. So, to get air out, we put a gizmo inline that makes the air change direction a LOT which makes the uncompressed chunk of moisture fall free from the air flow. There are two things that can increase the amount of moisture that is knocked free.
1. Increase the air flow - the faster the air is flowing across the deflectors, the more moisture is going to get knocked loose.
2. Increase air density - the thicker the air is before going into the separator, the easier the moisture will come loose
Once you have purchased your compressor, you are pretty much locked in to the air flow rate so nothing you can do for #1. But changing #2 is easy ... install a pressure maintaining valve. A simple PMV will restrict the air flow until pressure gets up to about 1800 psi.
To further process air, we add a filter chamber that is filled with a real fine filter medium called molecular sieve. Basically, they are little balls of material that has micro pores that trap moisture molecules that get past the moisture separator. To increase the efficiency of THIS filter we need to:
1. Increase the dwell time - this allows the air to spend more time flowing across the media, increasing the chance of moisture getting trapped
2. Increase air density - denser air means the moisture chunk sticks in the media better
So, assuming you don't have an adjustable size filter tower, the only other adjustment you can add is a PMV.
So ... this is really a no brainer ... install one PMV on the outlet of your filter so that it can maintain back pressure on the entire filtration system.
Every scuba compressor I looked at has a PMV before the outlet. I’m putting mine on the top of the Chinese filter. It cost $80 plus a few $ in fittings. Not much money for piece of mind imo...