Just wanted to tap the collective wisdom of the group on this one. I have a small twin-tank 4 gallon Porter Cable oil-free compressor that is not meeting my auto repair needs. I'll keep it for woodworking and small jobs like filling tires, but need a big honker for impact wrenches, cutoff tools, and light sandblasting on the old (57) Dodge trucks my wife wants me to restore.
I have 240V in the shop, and a budget of around $600. Looks like there are several oil-lubed single-stage compressors of about 60 gallons with 10+scfm at 90psi in that price range. A local store has a Porter Cable with some light cosmetic damage (paint on the tank is scraped down to the primer) marked down from $580 to $400. Comments?
I have a large single stage compressor but I wish that I had gone with a two stage unit. If you are doing body work, a sander or a sand blaster will really use the air. The single stage will barely keep up with my sand blaster and runs constantly. Go with the two stage compressor, it will not be that much more and will save you from having to trade up later. The two stage has a higher air pressure and capacity and will keep ahead of your air hungry tools.
As long as you are doing it, buy an upright tank model. They take up less space, and they DRAIN WATER so much better since the semi-elliptical tank end acts as a sump and ponds the water around the drain fitting. And yes, two-stage has a much higher volumetric efficiency as the air pressure builds so you DO keep up better.
You have gotten some very good advise so far ... do yourself a favor and just keep saving your coins and get at least a 5 to 7 hp, 220 v, two stage, upright unit ... anything else is just to small ... The absolute smallest I would even think about is a 60 gal. tank ... I have an 80 gal.... someday you will want to have a bead blast cabinet, and, also sand blast capabilities and you will be glad you got the larger unit ... makes working with air tools much more efficent and fun ... watch the classified adds ... A rig like I described will last a life time ... Mine works just as well today as it 15 years ago .. they require only min care and return max benefits ...
A horizontal tank will be better for air/water separation as the velocity of flow through is lower and hence less turbulence.
A multi stage compressor does not insure a higher volume of air flow, just more pressure. In fact it should have an intercooler and scrubber if working in high humidity conditions.
I have a 3 hp. twin cylinder on110v that compresses to about 120 PSI. It will run my sand blaster just fine.
True ... Volume is not normally increased just because of dual cylinders … but in this case pressure is (that’s why the dual pistons) … it’s hard to beat cubic inches for volume .. if you need the air at usable pressures at various points in a shop (even on long runs of hose) it’s good to have the higher pressures to drive it over the head lost due to pipe sizes and fittings … if you are going to run off a hose directly from the tank perhaps a smaller compressor will work for you … it all depends on what you expect to accomplish … I had a smaller compressor many years ago similar to the one you have, but it was constantly cycling and I was always waiting for it to built pressure. It just could not handle the loads of the air tools I needed to use. It could not handle a sand blaster other than a small siphon one I had .. and a bead cabinet like I now use would have been much more than it would have liked.
The bottom line is .. size the compressor to meet your needs a with an eye on your future needs … Mine was a vertical because of space now it’s the only type I want … and I don’t seem to have any problems with moisture in the air over a horizontal tank … I just drain the tank after the days use and add a water separator for spray painting which you must do regardless of configuration if you spray paint …
You will not obtain greater volume with the two stage. The first stage sets the volume you will achieve.
Then you could also use larger piping to reduce friction losses or if you increase pressure the piping will have to be of a better grade and should have an air dryer on the commpressor discharge to elimate water initiated rust in the pipes.
Volume is set by the first stage ...never a doubt ... he wants to use air in small shop and you can go to the extremes and blow the cost and practical appilication out the window ... and I don't think in a small shop .. home or industrial, that the air is going to be heated to the extent that you refer by the size air compressor that he expects to obtain within his budget ... as I said before just size the air compressor to your needs and be sure you watch out for your future needs ...
[img]/forums/images/icons/blush.gif[/img] Er.....aren't we overlooking the actual advantage of the two-stage here with the discussions on volume? [img]/forums/images/icons/crazy.gif[/img] Isn't two-staging done to preserve the VOLUMETRIC EFFICIENCY as the pressure builds to shut-off setting by allowing the individual stages to operate with a narrower difference in pressure. A moderate degree of intercooling is always nice of course. [img]/forums/images/icons/tongue.gif[/img]
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