What size compressor for air tools?

[bigdog]

What SCFM/psi rating does one need for a 3/8" air ratchet?

I just got a finish nailer and would like a small compressor that would handle it and the 3/8" ratchet that Sears has on sale for $50. This is just occasional use, I do not need top of the line for a contractor or mechanic.

Happy Thanksgiving.

[CFRay]

I looked at the Craftsman 3/8 ratchet that I have and it needs to run on 90 PSIG. I'd recommend at least a 15-20 gal tank size. Once you have one in the garage you'll come up with many uses other than the jobs you have in mind today. Bigger is Better! Good Luck!

[Whoaru99]

Usually the tools list the CFM requirement and 90 PSI is pretty common for stuff like that. I take it the specs are not listed in this case or you wouldn't be asking...

If it's Sears, you may want to call them to ask or maybe check their HSOforum...

[Guest]

Ratchets dont take that much air. If you dont mind hearing the compressor turn on here and there, just about any compressor with a tank should work. Dual stage(forgot proper term) work much better on keeping up the psi(compression on both strokes of the piston).

If you plan to use cut off tools, sanders, and some other tools that take a lot of air, you will be much happier with a larger dual stage compressor with a larger reserve(30-50 gallon) if you like to use your tool for more than a minute without letting the pressure build back up.

The dual stage compressors are much quieter and perform better. If your budget allows them(little more expensive), you will be happier with them. Single stage compressors are very loud and quite slow.

[river-rat4]

I am in the "Compressed Air" business.

Most tools run at 90 PSI. The CFM (cubic feet per minute) is what you are talking about.

A 3/8" rachet would only take about 3 CFM at 90 PSI. I think any "Sears" type compressor, whether it is single stage or two stage would get you by as long as that would be your only purpose, other than the filling of tires and floaties for the lake.

A two stage compressor will get you around 175 PSI, and a single stage produces about 125 to 150 PSI depending on the unit. The average person only needs 90 to 100 PSI for any application.

A pneumatic sander can take about 10 CFM at 90 PSI.

Keep this in mind when buying an air compressor.... Rule of thumb is 4 CFM of air at 100PSI per hoursepower. Many, I REPEAT MANY compressors on the market today play games with horsepower and CFM.(ever see an ad that says..."4.5HP & 5.5 CFM @ 40 PSI". I can tell you that 40 PSI will do you no good, other than pumping up tires and floaties. You could not get a ratchet to work on that. Again, 90 PSI is "standard" for most air tools, now find out how much CFM you need to run it at 90 PSI.

Electrically speaking a 5HP (single phase) motor takes around 21-22 amps to run with a 1.25 service factor, and that is 220 volt. That means you would need a 30 amp breaker to run a 5HP 220 volt compressor. A 110 outlet in a garage is usually 15 amp (sometimes 20 amps). My point is 110 volt motors/compressors, might say 4.5 hp but you can't run more than a 1 1/2 to 2HP(pushing it) max without popping a breaker. Comsumer "4HP, 4.5HP, 5.5HP, 6HP, 6.5HP, 7HP" units don't exist. Games are played with voltage/amps. There is no such thing as a 4HP motor (electric). Here are the electric mototrs available, others are not true HP's(1, 1.5,2,3,5,7.5,10,15,20,25,30,40,50,60,75,100, and so on)

Tank size helps, but remenber "A tank does not make air, it just stores it".

A single stage compressor will actually make more air (CFM) than a two stage compressor, up to 100 PSI.

Single stage versus two stage noise wise, not even something to consider. It is like comparing AM to FM. The difference in noise would be in (consumer units) oil lube or oiless units.

Oiless units can be started better in cold weather but have a short running life span and are very loud, oil lube units don't start well in cold temps but overall life is longer and are quieter running. (a whole nother story, consumer motors are only rated for about 200 running hours).

If you have anymore questions, I am more than happy to help.

(I would not expect you to buy from me, just willing to help out so you get what you need)

Be safe,

river-rat4

[theoilman]

Good info river-rat4.

One thing further - to make your lube- compressor easier to start in colder weather, use only synthetic compressor fluids (most compressor manufacturers now recommend and prefer synthetic fluids). AMSOIL has 5 viscosities of synthetic compressor fluids available, but the one for most piston compressors is the ISO-100 fluid (product code PCK). You can order direct by going through my site. Most 5hp units will need 2 quart bottles to service.

[river-rat4]

Synthetic oils work well in compressors.

Chosing the correct air compressor for the application is the key.

Do your research.

[email protected]

[bigdog]

That is some good information, thank you. What would be you recomendation, brand , etc for a portable compressor for indoor use (quiet)? Would be used mainly for a finish nailer but I would also like one that would handle the 3/8" ratchet.

I have a Campbell-Hausfield compressor without a tank that I use for filing tires etc. It must be oil less as it is very loud and I definately would not want to listen to that indoors all day.

[river-rat4]

bigdog,

If you would use it on a minimal basis, any "brand name" unit would be okay. Finish nailers take very little air (cfm) so a small 2 to 4 gallon tank would do it. A rachet will take more CFM so a larger tank would be better. Keep in mind that a 3/4 hp compressor is not going to handle the rachet for long. It would depend on what you will be doing more of. Tanks only store air, they don't make it.

For a quieter running machine, get an "oil" lube compressor. They are much quieter and typically last longer, downside would be starting in the cold. For house, go "oil" lube.

river-rat4