Information about plumbing compressed air is continued on this page.
The first page of information on compressed air plumbing, found here, talks about the plumbing of a home workshop type portable compressor.
The second page of information is about in-plant plumbing techniques.What is next?
As the drawing depicts, take the drop line feed off the top of the air main. Any water that has condensed in the mains will flow along the bottom of the air pipe, not at the top. Gravity works!
I recommend too that you install a manual drain at the bottom of the drop line, and take a feed from the drop line over to the equipment a foot or so up from the bottom of the tee.
If your equipment is using a high volume of compressed air, then air flowing down the drop to that equipment can still allow water vapor to condense out. Tee'ing off up from the bottom of the drop allows that condensate to flow to the bottom and to be drained off. If you find a lot of water at the bottom of the drop tee, consider installing an auto drain to eject that water regularly.
A manifold will allow you to bring one supply of air into one end of it, and then, via a series of smaller air ports along the side of the manifold plumb air to a number of different piece of equipment.
The greater the demand of air for that equipment, the higher the water condensate volume will be, and filtering the air just before it enters the application will remove any free water before it can get into your tools or equipment.
Downstream from the filter you will want to add an air regulator so that you can reduce the pressure to the minimum necessary to do the work. This reduces your operating cost somewhat, and at the same time, reduces or eliminates (depending on where the pressure is set) the pulses in the compressed air supply created by the air compressor kicking on and off.
If the air tool (perhaps a paint gun) really requires very dry air, consider installing an in-line air dryer where that level of dryness is needed.
Depending on the air tool or application, you may need a lubricator as well. Get complete information on air line lubricators here. My suggestion is that if you do not need a lubricator, do not start using one. Oil from the air line lubricator tends to flush out any factory lubrication in the equipment, and then, you will have to lubricate that piece of equipment from then on.
I hope the preceding three pages about plumbing compressed air have been useful. As always, if you have any question, please just ASK!