wheelsup Posted March 19, 2009 Report Share Posted March 19, 2009 I was wondering if any of you have any knowledge on air compressors. I was looking at a 21 gal unit that delivers 4.9 cfm @ 90 psi with a max of 125 psi. Would this be sufficient to run most run-of-the-mill air tools like 1/2" impact wrench, 3/8" ratchet, and maybe a nailer?When looking at their requirements the ones I've seen require right around 4 cfm. If I were to use a tool that used more CFM than the compressor produced, would it matter? Or would the compressor just have to run a lot? For example I was thinking that in the example above the compressor "produces" 4.9 CFM @ 90 psi however once charged up it would run a tool that needed 6 CFM for a bit before turning on, it just couldn't keep up if you ran out of air. Or is my thinking off base?Or should I be looking for something in the 6 cfm range?I know "bigger is better" but I'm looking to keep costs down and not buy something I don't need. Thanks-matt Link to comment Share on other sites More sharing options...
Dave 54 Posted March 19, 2009 Report Share Posted March 19, 2009 90psi is generally what most air tools run at. What you want to think about is the duration that you will be running the tools for. If you are porting and polishing you want one with a large tank and motor for quicker recovery. A dual stage is the best, but more exspensive, plus you will need a 220v supply to run it.I run a 33gal. with a 6.5hp motor, I also have a res. tank in line for when I am grinding, porting, polishing, or if I am running something that requires alittle bit more. Link to comment Share on other sites More sharing options...
bigric Posted March 19, 2009 Report Share Posted March 19, 2009 I was wondering if any of you have any knowledge on air compressors. I was looking at a 21 gal unit that delivers 4.9 cfm @ 90 psi with a max of 125 psi. Would this be sufficient to run most run-of-the-mill air tools like 1/2" impact wrench, 3/8" ratchet, and maybe a nailer?When looking at their requirements the ones I've seen require right around 4 cfm. If I were to use a tool that used more CFM than the compressor produced, would it matter? Or would the compressor just have to run a lot? For example I was thinking that in the example above the compressor "produces" 4.9 CFM @ 90 psi however once charged up it would run a tool that needed 6 CFM for a bit before turning on, it just couldn't keep up if you ran out of air. Or is my thinking off base?Or should I be looking for something in the 6 cfm range?I know "bigger is better" but I'm looking to keep costs down and not buy something I don't need. Thanks-mattThe larger the tank the better, but 21 gallons should be good enough for most work. Nailers take next to nothing; that's why contractors get away with those little pancake compressors. Another important consideration is the air hose--get good 3/8" hose; none of that 1/4" stuff. I keep my pressure around 125 psi but turn it down to ~80 if I'm going to be grinding on long projects so that I don't go through air so quickly (it'll still run forever while you're working). Link to comment Share on other sites More sharing options...
TEN8US D Posted March 19, 2009 Report Share Posted March 19, 2009 I'd avoid an oil-less compressor. While they're cheap, they're really noisy and wear out quicker.If you've got a 220v dryer outlet near your shop, that'd be a bonus that'd step you up into the big-boy compressors.I prefer a larger compressor for the volume of air they hold, reducing cycling. The bigger tank also helps out when using a high-SCFM tool like a die grinder or drill. If you can, plumb some hard lines with 1/2 or 3/4 copper or steel (NO PVC!) and you'll get even more storage volume. I've got 3/4" copper from the tank to the FRL and 1/2" copper from the FRL to the hose reel.I'm running a 60-gal Husky (Campbell Hausfeld) I picked up on craigslist for around $200 and am much happier with it compared to my old oil-less Craftsman. I wish I would've gotten a two-stage for higher pressures, but it suits me okay. You might even be able to find a good Ingersol-Rand for not much more. Added bonus: they've got rebuildable valves and ring kits for when they do wear out.As mentioned, use good 3/8" or even 1/2" hose and mail order some high-flow connectors from Grainger or MSC Direct. Link to comment Share on other sites More sharing options...
Che'_Moderator Posted March 19, 2009 Report Share Posted March 19, 2009 LOL and the short answer. Yes 5cfm@90 is fine for most tools. Link to comment Share on other sites More sharing options...
wheelsup Posted March 20, 2009 Author Report Share Posted March 20, 2009 OK thanks guys, I might go with a Harbor Freight compressor, mistake?$125 for 21 gal, 3 hp 120V 4.9CFM @ 90 PSI, with an oil reservoir.http://www.harborfreight.com/cpi/ctaf/Disp...temnumber=94667I was also thinking of buying used off Craigslist but can't find one that fits the CFM without being $400+ used. Link to comment Share on other sites More sharing options...
wheelsup Posted March 20, 2009 Author Report Share Posted March 20, 2009 The larger the tank the better, but 21 gallons should be good enough for most work. Nailers take next to nothing; that's why contractors get away with those little pancake compressors. Another important consideration is the air hose--get good 3/8" hose; none of that 1/4" stuff. I keep my pressure around 125 psi but turn it down to ~80 if I'm going to be grinding on long projects so that I don't go through air so quickly (it'll still run forever while you're working).It seems the compressor I was looking at has a 1/4" hose outlet, so would running 3/8" hose even help? Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.