Anthony said:

In addition to the excellent advice given by Bruce, I would suggest
automatic timer drains on the tank and your drip leg out of the main
line.

A simpler and less expensive method might be to add an auto "level"
drain inside your filter. Wilkerson and other manufacturers offer a
small float operated drain for very little $.

dennis
in nca

p.s. Grainger's used to have a page or two in their catalog addressing
proper air system design; anyone have a copy around?