The most important things to look at in an air compressor are air quality, and static line pressure. Just because a compressor is rated for a certain pressure, the cubic feet per minute rating is what determined the compressors ability to maintain a contant line pressure, even in cyclic demand conditions.
In our case, we are running four or five big milling machines that have a high static line demand. Open up six sandblasters, a stand-up walnut hull blaster and a dozen air handpieces going off and on periodically, and it can cause spikes-dips in line pressure.
One way to overcome fluctuations in static line pressure is a larger holding tank. We upgraded from a turbine style, tankless compressor to a large industrial compresser when we started to experience errors due to critical line drop. We are currently running a 250PSI Ingersol Rand machine with a 500 gallon tank. We have a 100 gallon, 100 psi tank for our dental operatory.
All air supplies run through a commercial cooler, 25 gallon condensation tank, and finally a 25 gallon cartridge filter. Because ambiant air temperatures here in So California can range from 115F to 32F, we have another drier INSIDE the building to collect condesation when the copper lines go from outside heat into the air conditioned environment of the building. Small canister filters are installed at each machine, and each one has a plastic disposable collodial silica capsule inside which turns from blue to pink when they absorb moisture.
The quailty of air as almost as good as what I use in my Scuba tanks, but more importantly, we save a ton of money on rebuilding handpieces and replacing milling machine spindles.
Moisture, oil contamination, dirty air being sucked in on the intake side of the compressor stroke, and organic debris all lead to poor air quality and premature failure of sensitive, precision high RPM tools. It also leads to clogged sandblasters and contaminated work surfaces. Regardless of the type of compressor you buy, try to spend some extra money on your filtration systems and maintenence and it will pay for itself in money saved on repairs and other problems.
I was going to post pictures of our filtration systmes, but I don't use a URL to store photos.
