Diffusion pumps

[Doug Coulter]

This all makes me wonder if something similar to my shop air supply might work out in a large installation such as John has. Here my shop air is piped around to all the stations (gosh, perhaps 15 or more) with very fat Cu pipe (1" is fat in this context) and the reservoir that alone gives is plenty -- takes awhile to fill with a 10hp compressor, as it amounts to maybe 50 gallons. One wonders how much you could get away with on a plan like that, particularly with turbo-drag pumps that work well into viscous flow pressures. Would a little extra gas inrush in one system compromise the others? Could various valves and gages (cheap ones like my pirani design here elsewhere) take care of that if each HV pump had a little reservoir? Hmmmmm.

My compressed air system loops the two floors of the building here, 360 degrees on each floor, and tied at diagonal corners floor to floor for max gas conductivity. In my case, it all has a little deliberate tilt so anything that condenses in there winds up down at the pump under the ground floor, for easy removal later.

I know I've heard of chemistry labs doing this at much crummier vacuum than a diff pump needs, and it works there fine. Makes all the disposal of any nasties a centralized operation as well.