This question has come up before. May be hard to find under the 'Search' function unless worded right. I didn't try either so I don't know.
Anyway, I have done a lot of air arc with smaller compressors. 12-15 cfm will work but will work the compressor full time. The bigger the compressor and the more tank you have the longer it will last and more efficiently it will work.
Most work can be accomplished without opening the air all the way on the torch. It still requires an awful lot of air to run it good, fast and clean.
I also find most of my work can be run at about 60-80 lbs of pressure. It doesn't require full time 150 lbs plus to get the job done.
While it most definitely depends upon the exact material, thickness, and application I find many people run too large of an electrode and too much amperage for the job they are doing. They also run way more air than they really need.
Just my two tin pennies worth.
Have a Great Day, Brent
I run a VMAC on my truck and it is an awsome little unit - 75 cfm and only a little bigger than the alternator. But I use some bigger air tools which use a lot of air - maybe even more than air arc though perfect for that, too.
Two disadvantages - killer expensive - more than $5000 for the kit for your truck. And you gotta run the truck engine and the welder to air arc. Sure, it gets the job done but all those sparks and noise aren't for free.
I kinda need it but you'd need to do a lot of goughin' to make that pay. If you're just welding ( or goughing) the airpack thing is a better configuration.
Oh, and they don't last forever - had to replace the compressor part of the kit once already.
They are not all they are made out to be. We have a very large IR screwdrive in our shop. It is only 17 cfm and like I said is very big. The engine drive on my truck is 25 cfm. We have had alot of problems out of ours from not using it enough. The IR repair man said they are made to run at almost 100% duty. That is the advantage over a piston type. They also produce very dry air so they are good for plasma and painting. But that is a shop unit I don't know about the truck mounted models.
I think my buddy said it runs all the time or something, not even sure if it had a tank on it or if it just pushed enough air without storing it. I didn't see a tank up top on the truck anywhere, it's been over a year since I saw the truck.
Screw and vane type compressors can be run without a tank [if a large enough compressor is used]. The intake air is regulated to maintain nearly constant output pressure.
Sounds like Your shop compressor has a refrigerated dryer attached, they provide very dry air, but add another level of complexity, bulk and power consumption.
The actual screw compressor pump itself is pretty small for it's output compaired to a piston type compressor.
It does have a dryer and I think it's an 80 gallon tank. The IR repairman said they sold us the wrong compressor. He explained how those are for almost constant use (auto body etc) There are times that ours does not turn on for a week.
Yes, that is a large investment for ocasional use. The places I worked were serious air users. (2) of the shops I worked in upgraded to screw compressors, one for efficiency's sake, and the other due to the need for greater capacity.
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