Is a 20 gallon compressor enough for air impacts?

[lbhsbz]

An appropriately sized impact should only need the trigger depressed for a couple seconds for most fasteners. On some occasions, you have to sit their and let it rattle on something for a while, but not most of the time. A 20 gallon compressor works fine on impacts. Air ratchets....you'll be taking a few breaks if doing multiple bolts (think timing cover/oil pan/trans pan, etc..)

 

[john.k]

You can run any air tool with a small diesel compressor ,around 125cfm is a good size ,and they often sell very cheap ,cheaper than what a dealer would want for a similar motor.

 

[Metal-Marc]

Never had any real issues with mine, but now you guys have me curious to see if it would be better without the regulator. I mostly run my 1/2 inch drive and 3/8 drive IR impacts, and a 3/8 Mac ratchet.
My air die grinder doesn’t get much use since I have an electric one, but maybe it would without the regulator?

I might also try this without a regulator.

 

[theoldwizard1]

Air tools tend to be a lot cheaper on the secondhand market and I think most stuff we do isn’t going to be anything like an actual repair shop so it’s not like we’re going to be using them non stop all day.

I used a CP 1/2" impact to remove the wheels and a broken spring on a travel trailer with this compressor. I had to wait for the compressor a couple of times, but it got the job done.

 

[GeoBruin]

I used a CP 1/2" impact to remove the wheels and a broken spring on a travel trailer with this compressor. I had to wait for the compressor a couple of times, but it got the job done.

I love the CAT compressors but the 125 max psi could be an issue when you're trying to squeeze the beans out of an impact. At 40 cfm you're looking at over 16 psi in pressure drop from a 25' long 3/8" hose alone, not to mention losses from fittings and of course the reg. Before you know it, you can run it wide open and you're still only seeing 100 psi at the tool. And if the torque test channel has taught us anything with their "best case scenario" tests, it's that some guns really like pressure.

 

[kaymccampbell]

I ran a Speedaire 16 gallon oilless compressor for about a decade. It ran the rattle gun, nail guns and painted cars. I was plenty pleased with it. It sucked at any long running air use like sanding, sandblasting and die grinding. The 60 gallon twin cylinder machine I have now does everything just fine.

 

[john.k]

Bigger ID hose is the simplest fix...........next would be another air tank to double capacity .

 

[Shiftless]

Here is an extreme example.
I have a 2 gallon pancake air compressor that I use for airing tires and running a brad nailer.
There was a rusty nut on an old vise swivel base I was restoring that wouldn’t yield to a socket on a big breaker bar. So I hooked up the hose to an old half inch Dayton air impact with a proper impact rated socket. I set the regulator to 125. The nut broke loose in about 2 seconds.
Could I use that set up to remove all the wheel lugs on a semi? Maybe. Give me an hour or two. But for one fastener? Sure !!

 

[Jswain]

I love the CAT compressors but the 125 max psi could be an issue when you're trying to squeeze the beans out of an impact. At 40 cfm you're looking at over 16 psi in pressure drop from a 25' long 3/8" hose alone, not to mention losses from fittings and of course the reg. Before you know it, you can run it wide open and you're still only seeing 100 psi at the tool. And if the torque test channel has taught us anything with their "best case scenario" tests, it's that some guns really like pressure.

And this is exactly the problem with people who read "90psi" and set the tiny built in regulator to 90psi, then a crappy fitting, with 50ft of 3/8"(or 1/4") hose, with another crappy fitting and then wonder why the gun is underpowered & the air compressor will never keep up.

2 stage eliminates a lot of the problem, but I got by just fine with an 8-10 gallon tank up to 125psi doing wheel swaps, brake jobs etc. I didn't regulate the air down & I had my 25ft of 3/8" hose coming straight from the tank with high flow fittings.

 

[IRQVET]

I'm in another camp, I bought an electric impact for occasional use, so I could stay with a smaller CAT 20 gallon air compressor. The ROI for was frequency of use, which for me, wasn't very often.

 

[908Jim]

I'm in another camp, I bought an electric impact for occasional use, so I could stay with a smaller CAT 20 gallon air compressor. The ROI for was frequency of use, which for me, wasn't very often.

What was your problem with the 20 Gallon compressor? Just having to wait for it to catch up to run the impact?

 

[IRQVET]

What was your problem with the 20 Gallon compressor? Just having to wait for it to catch up to run the impact?

Was a bigger issue with the CAT 10 gallon, but still an issue with the 20 gallon. But being honest, that CAT 10 was my first air compressor, and I asked that thing to do all sorts of stuff I had no business asking it to do. Impacts, DA's, and Sand Blasting cars was just a few fool hardy things I tried to get that thing to do. It did it all, just with a lot breaks in-between while I waited for it to catch up.

My CAT 20 has the same motor on a larger tank, but I learned what it can and cannot do as an oilless compressor with the CFM it has. No plans to torture this one like I did the last one. Crazy thing was, after 10 years of abuse- it ran like a champ the day I sold it off, lol.

 

[GeoBruin]

Sorry I'm late with this (I've been sick the last couple weeks) but this thread inspired me to run a fresh series of tests to see what the true air demand of a 1/2" impact wrench is, and to test the wrench under various scenarios (regulated vs. unregulated, 3/8" hose vs 1/2" hose, etc.).

I hope you find it useful.

I hope to add time stamps to the video so you can jump ahead to various points but I haven't got there yet.

Enjoy!

 

[Jswain]

Sorry I'm late with this (I've been sick the last couple weeks) but this thread inspired me to run a fresh series of tests to see what the true air demand of a 1/2" impact wrench is, and to test the wrench under various scenarios (regulated vs. unregulated, 3/8" hose vs 1/2" hose, etc.).

I hope you find it useful.

I hope to add time stamps to the video so you can jump ahead to various points but I haven't got there yet.

Enjoy!

Excellent example of why it is not a great idea to regulate a 125psi compressor when running impacts. A lot of people will be running a 50ft 3/8" hose too, so I'd imagine even worse.

 

[Dakotadadv8]

I have used Makita compressor Mac 2400 with air impacts and air wrench.

 

[GX460DIYguy]

I thought about this thread yesterday and looked at the compressor. It’s actually a bigger tank than I remembered. I’m gonna get some cheap used stuff and a water separator to see how it performs.

 

[Semi-hole mechanic]

You really need to look at pump delivery (cfm), rather than tank size. Tank size is just reserve capacity, and cfm is what the pump can deliver. Compare delivery vs consumption if the tool you are using.

i survived for years with a 2 hp 240 v Sears belt driven compressor. It worked well with an air impact, and would supply enough air to paint body panels, but there was a lot of waiting to paint an entire car.

didn’t do great with DA sanders.

We painted an entire R series Mack with a 13 cubic ft dump bed using a little 20 gal Huskee by TSC that was probably 20 years old at the time and an old Binks canister type paint gun. We learned that you only filled the paint cup about 2/3 full otherwise you ran out of air before you ran out of paint. I still have that air compressor in my garage and use it occasionally to run my 1/2 inch impact wrench, because it’s belt driven and quieter than my newer HF 8 gallon, that I bought to replace it when I thought the motor was bad (just a loose wire in the pressure switch), even though it’s 50 years old.

 

[Mr_B]

Reality is in real world use you can get by with the better higher PSI small belt driven compressors for impact wrenches up to 1/2" without much drama, .
Better high efficiency air motor tools will make better use of your air supply limits .
Likes of the Astro Nano impacts do well on smaller compressors and if keep short hose lengths and minimal restriction you will get pretty good torque potential from it and get most tasks done with bit of patience for higher damand tasks .
At home in my barn I use small under 2hp compressors, they run impacts pretty well unless need real long tool run time .
My solution to that was add a second small compressor with auto switch ability so can run as tandem pumps when needed, you can also just run single but keep 2 tanks hooked up for the increased storage .
Works well, can be fairly low cost as can go real cheap direct drive units & can run on basic wiring without need do major curcuit/power upgrades .

 

[tak1313]

As other's have stated, it has more to do with CFM capability than tank size compared to the requirements of the tool.

Before I got my 60 gallon Husky (made by CH), I had a 20 gallon Craftsman, which was RATED for 5+cfm @ 90psi. It did OK for impacts. I then happened to get a 4 gallon CH "contractor grade" at the dump that only needed a new reed valve, but was rated for 6cfm @ 90psi, and it did SIGNIFICANTLY better with tools such as impact wrenches.

Tools like impact wrenches are USUALLY operated in bursts, especially in home use, so smaller compressors like above do OK, but not so much with stuff that needs continuous high flow, such as sanders, high cfm air hammers, etc.

For me, soon after I got the 60 gallon, I've rarely touched it (about 7 years now) because Milwaukee started coming out with their uber M18 stuff, and I haven't looked back. At the time, I picked it up because HD had the display on clearance (because of "new models"). They were selling it for $275, and just on a lark, I asked the floor manager if they would take $200 (or something like that), and he agreed on the spot. I didn't think he'd say yes, but once he did, I felt compelled since I was the one that offered.

 

[Citation]

I suspect maybe overlook the output parts of the system. Yes, impacts are burst tools so they can run effectively even if only for short bursts off a small compressor. The only factors that matter for the small burst are tank pressure and the flow restrictions from the regulator, couplers and hose. For at least a few moments a 4 gallon tank at 120 psi has the same driving pressure as a 120 gallon tank at 120 psi. Tank size and pump flow rate don't matter for that brief time. The inline flow restrictions are going to be the difference and normally the bigger tank/pump systems will have output parts that allow greater flow.

So if you have a little compressor and you want just a bit more umph out of the impact wrench, consider changing/bypassing the regulator. Also if the output come out of a restricted T or other such thing, consider changing that as well. One of the things I like about the Emglo 4 gallon twin tank roofing compressors is the output is just a regulator attached to the tank. The pressure switch is separate. Many compressors use a single output into a multiway base on the pressure switch. That restrictive multiway base then flows into the regulator. Lots of restriction when you want full flow.

 

[dnschmidt]

You asked a very specific question and the answer to that specific question is yes, you can run an air impact and possibly an air hammer normally which run quite intermittently. The problem is that's ALL you can run as any continuous tools like a die grinder or paint gun will never work. You'll also be able to pump up your tires.

 

[Mr_B]

You can do other things in small scale jobs.
They run impacting ratchets, my IR small disc/pad grinder works pretty well, grease guns, sealant guns, rivet/nailer tools, air hammer, leak down testers, plasma cutter,air over hydraulic jacks/rams .
you can spray rust prevention oils, underseals and it will spray a panel or 2 not too much bother (will need be decent spec smaller compressor with good setup for decent results but I done couple good off car door and wing full color change paints no big drama on similar spec compressor to the linked craftsman ...