Back in the 1979-1980 era, I had a summer job for Bulova Watch - they had taken the mfg out of their plant in Astoria (mostly) nad turned it into a warehouse. The thing is, the plant air compressors were there. Cant remember the exact size, BUT there were TWO, and if I remember correctly EACH was something like 75 or 100 HP - BIG reciprocating compressors - the bore had to be like 10 Inches with a LONG stroke. As most of the plant was shut, we only ran one. I never saw the air tank - it was a "ROOM" in the back
That place was strange. Picture a building that you make watches in, and how clean you have to keep it - despite it being a warehouse, it was still kept that way, and the small mfg that was left was in a clean room inside THAT (think it was stuff for the Military)
ODD things I knew because I ended up on the HVAC staff - like the tache that every 'mechanical room' (which had at least 3-4 AC compressors in them - most 8 or 9) was designed that at full load, there was still at least one SPARE compressor, so that by just changing valves, we could keep the system at 100%. Ditto the cooling towers - each of the 4 tower rooms had a spare tower (and yes, the towers were INSIDE, and could be closed off from the weather, or the space fan vented)
The OTHER part - the building ran at 100% fresh air - NOT recirculated, and the building was kept at a SIGNIFICANT positive pressure, to prevent dust/dirt from getting in, and on top of that, all air used was electrostaticlly precipitated - aka the builing - all of it, from the lobby and everywhere else, was basiclly a clean room!