Air tool newbie here.



Currently weighing the options between an electric impact wrench and an air setup. The 1/2" drive 500 ft-lb air impact wrench I saw at Lowe's requires 5 CFM @ 90 PSI. When I looked at the compressors, only the very large "human sized" compressor tank was able to deliver more than enough air (~11 CFM @ 90 PSI). All others were just shy, with most maxing out at 3 CFM.



Looking to get into impact wrenches to make automotive work easier on the weekends. I don't need some thousand dollar setup, but would like to see if air is still an option. Otherwise, I can get a DeWalt 1/2" electric impact that does around 320 ft/lb.

If you have a large tank, then you should be OK.  Just don't run the impact for extended periods, let the pressure rebuild and the compressor rest some as most compressor aren't designed for a 100% duty cycle.
  You can add an extra tank to supply air.

I run my 1/2" 625 lb/sq.in impact off of a pancake compressor.

It will kick on after I remove 10 lug nuts.

Tank size, pressure, and CFMs figure into what you can use.

If you are not using air constantly, you don't need a compressor to keep up. Things like air impacts are pretty easy on air use as you use them for short times. Grinding, cutoff, painting, etc are a lot more taxing as they are using air constantly for long periods of time.

A smaller, good quality (think IR, not HF), air compressor should serve you well. Look for something that has a high PSI. a 35 gallon tank full of 165 psi air is a whole lot more than 35 gallons of 95 psi.

Sounds like you plan to use yours about like I use mine. I've just got a Craftsman 26gal (IIRC) vertical unit and it does fine for swapping a set of tires out or breaking bolts loose etc. It has plenty of short-term CFM for that kind of stuff. You won't be painting or sanding any cars with it but for air wrench or impact wrench work off and on it has been plenty, and very convenient. Big enough to have some capacity but just light enough to through in the back of the truck without breaking my back to go help out buds every now and then.

My primary compressor is pretty small... around 1 gallon.. made primarily for airing up tires and brad nailing. Do I have the option of adding an auxiliary tank to make it more useful with air tools? I have no problem waiting for the tanks to refill since, like all of you have mentioned, my use with the impact wrench will be very intermittent.

I used a 30 gallon tank for years and did did everything I needed to do. A 20 gallon portable would probably also do what you need.

Have ~20gal horizontal craftsman compressor that has run 1/2" impact, 3/8" rachet, die drinder, and cutoff wheel.

It's not ideal but it'll do it. Just have to wait a bit for it to refill sometimes. Good thing is it's pretty portable so you can haul it to the project