As it happens, my 11 cfm, 60 gallon compressor developed a leak in the tank this week. I thought it was the drain-****, but it is coming from one leg, welded to the tank. Whether a result of welding error, or 5 years of vibration, I don't know. I use my compressor daily, at about a 60% duty cycle, in a small production shop with 1-2 people. The primary use is a cnc plasma table and handheld air tools. When I have both going, this compressor gets very little idle time.
Since I lean on it so hard, I was immediately uncomfortable with even considering a repair on the tank. It is drained regularly, and often, but it's one of the most critical parts of my daily operation. Being a little undersized, I started shopping for an upgrade. In fact, I spent the afternoon shopping and visiting with other shop guys about their preferences, experience and insight. I had pretty much decided on a new EMAX two-stage piston compressor, rated 19 cfm @90 psi, with an 80 gallon tank. It is also rated for 60% duty cycle, with continuous run options. That should easily handle my needs, with room to run my blasting cabinet occasionally. I also had set my mind to spend an extra $400, or so, for the quiet intake system, rated at 58db. That's quiet! It does have a belt drive, and disc valves, though, so I'm skeptical as to how quiet it really is. I decided to log on to GJ to see if anyone else had any info about it, but was fully prepared to order one tonight.
And then Ryan posts this story! It didn't take long for me to reconsider. I figured out the scroll compressor quickly enough. That's old tech in the HVAC world. Oil injection on the front, and separation on the discharge, is standard on any screw type compressor, so that's not scary. What I really like is the complete lack of reed valves, disc valves, pistons, rods, etc.! That's awesome! I decided to take a chance on the lower cfm, vs my goal, but I'll still have a second compressor on standby, so I needn't place the combined load on this one, if we get busy. So.... I ordered one. I think it will be great for 90% of my work, and I'm prepared to see how it goes on that last 10%. Thanks Ryan!
sidebar: I actually have a 32 cfm rotary screw compressor, but no 3 phase power. The phase converter required for a 10HP motor would be about $3500, and a single phase motor would run well over $1000, plus installation. So, if you're in the market, hit me up. It's in great shape, with a known history, and only 3500 hrs on it.