Grant Erwin wrote:

Air compressors add like capacitors. Run each compressor to a common
supply pipe via a check valve and you can add as many as you like.

A big deal with plasma cutters is drying the air properly, however. You
haven't mentioned how you plan to do that. Air comes out of an air pump
very hot, and containing a lot of water vapor. This vapor can not be filtered,
as it is gaseous. To condense the water the air stream must be cooled, then
the water droplets can be filtered. Some guys have reported success with
copper tubing coils in a drum of water. Many pro shops use refrigerated air
dryers. Harbor Freight sells a cheap refrigerated air dryer for $299 but I
don't know how well it works. If you decide to buy one then please let us
know how well it works.

Grant Erwin
Kirkland, Washington

A second inline tank will help alot. Running airline up after the tank , then down
to a filter is a good thing to do. A filter immediately after the first tank is
almost useless. Run as much line as possible to the plasma cutter with another
filter located as close to it as practical. Before getting a large secondary tank
I kept a small portable compressor sized one in an old refer. The air went from
the 80 gal tank through rubber air hose into the tank in refer and then on to the
network. Amazing how much water I would drain from that thing.

mj