Interested in this. I decided to get a second (smaller) bottle as a backup instead because I live in Cumbria; a pretty damp part of the country and I worry about the water vapour which is always in air, getting into my guns. Where I used to work (now retired) we ran nice German 11kw industrial compressors and removed about 30 litres of condensate from each on most damp or rainy days. We cooled the air before it got to the dryer.
How much water does a hand or portable electric pump remove? I imagine that using a hand pump, one would have to pump slowly and have the trap quite a long way from the pump to get the air cool enough to drop much moisture out of it. How effectively do the portable electric compressors do this? A 300 bar heat exchanger sounds a bit special; or am I missing something?
I have the luxury of using bottled air and I get them filled at a dive centre. This is because they supply breathing air and so far as I know; breathing air is always well filtered and dried.