Best air compressor for air impact wrench


My old air compressor was lost to a fire and I am looking to replace it. My main uses will be filling tires and such but I also want to make sure it can reliably run an air impact wrench for extended periods. I have a chainsaw I don’t need and put it up for trade on a local classifieds site. Someone has offered me a Charge Air Pro 5HP 20 gallon oil free compressor. I was always under the impression that I wanted an oil lubed version for durability. The only reason I can see wanting an oil free is if you are running a paint sprayer where oil contamination is a concern.

Is this compressor a good fit for my needs or not?


It should if its runnin’ okay. One parameter you skipped is the max PSI. I’d recommend at least 150 PSI for a torque wrench, but 5HP 20 gal compressor should have no problem with that.

Oil free is fine.

However, my personal experience with “swaps” like this has not been good. I’ve always found that the “swapped” item was not as-advertised. Some people unload busted items that they can’t sell for money by “swapping” them for something else, on the basis that people swapping don’t check the item out as thoroughly.


I dunno, I’ve got a 5 hp oil less and while it suits me fine, it won’t handle any air tools very long whether spray gun, impact, sander, etc. Oil less are strictly cheapo and throw away. Impact drivers take a lot of air so I really think you need one of those large tank stand up units with the belt driven pump, 220v. Not sure how big a tank or HP but the ones in the $700 range at least. My humble opinion but you can never have too much air. I just don’t have a good place to put it.

Come to think of it, I’ve got my garage piped for air as well as piped to the basement. So if my wife would let me, I could put a big one in the utility room right under her computer work station. Naw, better not even bring it up.


Bing, how many gallons is your tank? What’s yours rated at in PSI? Have you checked your lines for leaks?

No homeowner needs a belt driven 220V unit. There are lots of 115V units with sufficient ratings and capacity for a homeowner’s occasional use.


mine is a 220v belt driven two cylinder 10 HP 80 gallon tank.


The Same. I don’t know. I’d have to look but like I said, its fine for me. If I were going to do more body work, I’d want a bigger one. The OP said though: " want to make sure it can reliably run an air impact wrench for extended periods". If you are going to run an impact wrench for EXTENDED periods, you need a bigger compressor.

Edit: Ok I checked. Mine is 13 gal, 5.1 cfm @90 psi, 5 hp. An impact wrench will run anywhere from 5-8 cfm on up, so depending on the air use, need a bigger compressor for extended use. Mine is fine for tire rotations etc. but not for extended use. I need mine to fit under my sink though and wired to a switch so I can’t go much bigger. Thanks for reminding me though. My last one lasted 9 years and this one is 12 years old, so I’d better be ready to replace it at any time.


i have an old craftsman compressor that size. it works great for changing tires and all my auto needs


You need to know the SCFM (standard cubic feet per minute) rating of your impact wrench. This is the volume of air the tool needs to run at spec. This rating is usually given at 90 psi. A compressor that goes up to 120 psi is fine unless you feel you need to push the envelop. Just make sure the compressor you get is rated over that SCFM requirement.

I agree on the reliability of the oilless compressor.

Right now the cost of battery impact wrenches are coming down. Something to consider if you don’t have other air tools. You can always get a small inexpensive compressor for filling tires and blowing stuff off. It depends on you big picture.


Got it, bing. One factor in the OP’s favor is the tank capacity. A larger tank allows longer tool use. A given SCFM takes longer to draw down greater volume.

I’m still of the opinion that this compressor will be fine for the use described by the OP, however I’d still be very leery of the swap deal. Usually, if someone offers a swap, they know something they’re not telling. Usually they’re trying to dump something that isn’t working right that they can’t sell.


Rate home air compressors at CFM or amps. The horsepower ratings are usually measured on the marketing department’s Liar-Liar-Pants-On-Fire dynamometer by an employee named Pinocchio.
Commercial 3 phase air compressors have more honest horsepower ratings. The “5 horsepower” three phase air compressor in your mechanic’s garage will totally outperform your “6.75 horsepower” 115 volt home compressor because when NEMA says “5 horsepower”, they mean continuously without overheating, not just for a moment during motor start.


Gotcha! I found some more information on the unit. I have decided not to trade on this and made the decision before seeing the comments here. The brand is Devilbiss and the unit isn’t very expensive even new. I am not saying is a bad unit but just worried about wearing it out quickly. My last one was a cheapo but oil filled. Sure, it didn’t always recover real fast but suited most of my needs and ran until an accident destroyed it. I think the PSI on this unit is 125 or 150.

Several other friends have told me to avoid the oil free versions for my intended work. I think it would do for a while but probably isn’t the ideal unit for me with the motor running so much. I am going to hold out for a different unit.

I once had one of those $15 cigarette lighter tire inflators that began losing compression in the pump. I took the unit apart several times and put oil directly into the cylinder which would restore the pressure for a time. Eventually something else broke unrelated to the cylinder and I trashed the unit. I wonder how this would work on a larger compressor.


For air-tools, especially 1/2 drive impact wrenches, bigger is better…A big tank and a big two-stage compressor…That way, the compressor can stay ahead of the tools and not the other way around…