Air Compressors

[suzook86]

So, I'm looking for ya'lls experience with air compressors for the garage. I'm thinking somewhere around 6-10 SCFM @ 90 psi / 20-30 + gallons, but still questioning oil or oil free. Any thoughts and comments about types/manufacture will be appreciated, thanks.

[DeesZ]

I am not an authority on compressors, but have learned a lot about them over the last several years. I decided to get a "larger" unit than the little one I got several years before. I did some research before getting one, and I'm glad that I did, because I am quite pleased with my purchase. Here's a few things that I've learned... anyone with corrections or additions, please post them.

Air compressors are rated by horsepower, pressure, and cubic feet per minute (CFM) of output at a given tank pressure. Proper compressor sizing will provide you with suitable performance and longer compressor life (because you will not 'overwork' the unit). A good way to choose a compressor is to first decide which tools you are going to use with it; the compressor should exceed the CFM requirement of the largest tool you will use by probably at least 1.5 times. If you plan to run more than one tool at a time off the same compressor, add the CFM's of the tools together before multiplying by 1.5.

Generally, your biggest draw on air will be tools like sanders, grinders, sandblasters, etc. They need a continuous flow of air and will need larger, more powerful compressors to meet the demand.

Another issue to consider is what is known as the "duty cycle". The duty cycle is usually expressed as a ratio - how much time the compressor can safely run within a given period of time. A common "duty cycle" for compressors is 50%, meaning that the compressor should not run more than 50% of one hour... During the "on" time, the motor is pressurizing the tank. During the "off" time, your tools are running on the air stored under pressure in the tank. If your tools are draining the pressure off too fast, the compressor must run at more than 50% of the time that you have it in use. (With the 50% duty cycle the maximum pumping time per hour would be 30 minutes.)

Horsepower ratings of electric motors can be measured several ways and the figures seem to have been abused by manufacturers over the years, so they are not a very reliable way to measure performance. The CFM and pressure ratings of an air compressor is, in my opinion, the best measure of how a compressor will meet your needs.

I assume that you are looking at a piston type compressor. There are several types of those to consider..... single-stage and two-stage. Single-stage compressors usually have one or two pistons that compresses air and delivers it to the storage tank. The single-stage system is normally found on light or medium-duty compressors with a maximum rating somewhere below 150 pounds psi. Single-stage compressors are adequate for many of our needs. Two-stage compressors have two pistons that compress air. The first piston compresses the air and pushes it through a check valve to the second piston. The second piston further compresses the air and delivers it to your storage tank. The two-stage system is usually found on better heavy-duty compressors with maximum ratings above 150 psi. Two-stage compressors are good choices for heavy use environments.

Then there is the decision to get an "oil-free" or "oil-lubricated" unit. Depending on what your needs are you may not have a choice. Oil free units require less maintenance, no oil changes, etc., but some people claim that they do make more noise and will not last as long. They are good for a lot of applications, and I know many happy users of that variety. I have very limited experience with oil-free units, and I have no complaints with them. "Oil-lubricated" units are most often found in more demanding environments. Some people claim that they are a bit quieter and that they last longer. Of course there is maintenance involved with oil changes. Personally I prefer the latter variety despite the maintenance (I have this 'thing' about parts rubbing each other without lubrication.... what can I say?) Any variety that you will get will be loud. I have never been around a quiet one, so consider 'placement' in your garage, and maybe some noise control. In my opinion, an absolute 'must' first step in noise control is adding vibration dampers to the feet (or mounting points where the unit meets the floor). Just get a good set before you even install a larger unit.

Sticker price can be an eye popper for a nice unit, but don't skimp if you can possibly swing it. Consider what you may wish to use it for in the future, beyond your immediate needs. A good heavy-duty unit new will likely be between $900. ~ $1500. This is where patience can come in. I decided to look for a used well cared for unit. Found one (DeVilbiss brand) on eBay for $300.(plus a 150 mile drive) with about 50 hours of use - looks and performs like new, 80 gallon tank, oil-lubricated two-stage, and delivers 17.4 SCFM @ 100 psi & 16.9 SCFM @ 175 psi. I am very happy with the unit. I thought that it would exceed my demands very well. It has ended up just meeting my current demands with a media blasting cabinet. I'm very glad that I bought beyond my anticipated needs/requirements because I keep finding more ways to use lots of compressed air!

I hope this helps you in your decision. I'm certain others will have good input as well.

Here's a picture:

[TexasRider260Z]

Excellent and informatory post by Dees and even better shopping !

If you cant find a deal like that I strongly recommend getting the best Ingersol that you can afford that matches your requirements. You will use more air than you think - especially if you are painting, blasting or using a drill - these really burn the tank down. Probably $900 - $1500 though.

I am sure that many guys have gotten good service from the Campbell Hausefield Home deopt etc stuff but the Ingersol will be running for a long time to come and is much more likely to have parts should they ever be required.

[JohnnyO]

Found one (DeVilbiss brand) on eBay for $300.(plus a 150 mile drive) with about 50 hours of use - looks and performs like new, 80 gallon tank, oil-lubricated two-stage, and delivers 17.4 SCFM @ 100 psi & 16.9 SCFM @ 175 psi. I am very happy with the unit.

WOW! Nice find John. I looked for 3 months on ebay and CL locally and couldn't find a quality deal. Ended up buying a new 60 gal porter in June for $450 and am about ready to trade up because it just doesn't keep up when running the blasting cabinet or pot. Not such an issue with the pot because it only holds about 70# and needs to be refilled every 15 minutes, but the cabinet is another story.

John

[Bonzi Lon]

I have this Kellogg-American 5 horse, 2 stage, 5 1/2 foot long air compressor I bought in 1980. Funny part of the purchase was it came with a house.

Bonzi Lon

[suzook86]

Thanks for the responses everyone, this has given me more to think about. Unfortunately, price will now be a bigger factor, especially given I would also like to sandblast. Great info DeesZ, got me to expand my searching to Craigslist & ebay, good stuff.

[DeesZ]

Be patient with your shopping. It will come.

I did the same shopping for my blasting cabinet. Patience paid off there well, too.

[vercingetorix]

Hello,

I settled on a Cambell Hausfield from Lowes w/ a 60 gallon tank, 240volt for 389.00 I figured I check the oil in my car how much hassel can it be? Had a smaller one but all it did with air tools was massage the bolt head gently, this one makes the tools do whay they were designed for,and I never run out of air.

My2C

[Darrel]

stay away from oiless compressors. They are only marginally good for airing up tires.

[vercingetorix]

My small one was oiless was good for nail guns it was hopless with any air tool