Ha, ha,.....
yeah, I get that a lot. Easiest thing for a fast read on it is this directly from the Fuji web site....
http://www.fujispray.com/history-of-hvlp/Actually turbine guns are the reason we ended up with HVLP compressed air guns in the first place.... Long, long ago in a galaxy far,far, away (sorry, couldn't help myself) some joker out in California tested the efficiency of a turbine based set up, did some measurements of it's air output at the cap and made the erroneous conclusion that 10 psi max is what is needed at the gun air cap for an efficient transfer of materials from gun to surface. The Southern California Air Resources Board was the first to adopt that as a standard. Problem is....autobody shops couldn't make turbine guns work for crap because the tech. back then was simple 1 and 2 stage units making about 4 to 6 psi max which meant that the siphon style guns also had that little bit of pressurization of the material in the cup.....bottom line....super duper orange peel that nothing would fix. Immediately seeing that these new standards were going to almost eliminate current "old style" guns almost everybody and their mothers starting producing what I'll always refer to as a "step down" style HVLP compressed air gun. By making some changes in the way air is managed in the gun you ended up with that 10 psi max cap pressure while increasing overall cfm. Efficiency of materials transferred went up from 35% (think old Binks #7 gun) to around 65%.
Now on to the modern world of multiple turbine stages.... More stages= more pressure, more cfm. My wood restoration shops main turbine is a large 4 stage. We can achieve about 92% efficiency of transfer allowing us to dial it down to about the 1/4th the size of dime pattern all the way up to about a full 14 inch fan. We run directly from 5 gallon pots and instantly snap on our quart guns loaded with different stains, custom lacquers colors, and glues.
So that's the world of turbines, enjoy......