Brand name is important to ensure quality motors are used. Aside from that, the important things are: The cubic feet per minute rating and the gallon capacity.

Without both, you'll run out of air quickly. Horses generally are sized to gallons anyway.

Less gallons means you'll have a short blast with an impact gun, but it will run a small nail gun all day.

I've had a 5hp/twin cylinder, 30 gallon tank for almost 30 years now and never run out of air for anything, except sandblasting.

Expect to pay at least $300 for a minimal decent quality setup.

Running HP is all that matters as for air delivery. Peak HP makes a unit look bigger. A true 5 HP will deliver about 18 to 19 CFM @ 125 PSI.
A 5 HP peak is usually a 2 HP and will deliver 6 CFM max at 125 psi.

Hey baymee and green valley.

Thanks for your responses. If I were to buy a 5HP air compressor, do I need 220V to run it? Or is 110V good enough? I think I'll probably go with an oil one versus the oil-less, since from what I read, they are supposedly quieter.

baymee - what brand name and model did you buy a few years back? LOL! Probably can't find one like it, but it sounds like a good one.

green valley - So CFM is dependent upon the true "running HP" versus the peak HP claim. I see where you've dealt with a number of air compressors, so any recommendations for a specific brand or two given what I've described as to how I intend to you it?

What does the gallon capacity really signify then? Do I interpret this to be "air pressure" that is stored and available for a period of time before the air compressor "kicks in" and replenished the used air pressure supply? If this is so, do I interpret this to mean the larger the gallon capacity, the potential longer period of time 'in between' the air compressor sucking in new air to be stored? I probably 'sound' silly here, but am trying to understand the process/functionality of how the air compressor actually works too.

Thanks again for any and or responses/comments/attaboys and/or "you dummy"'s. :) Trust me, I'm thicked skinned. LOL!

bbbbosox

The larger the tank, the more air can be drawn until the compressor kicks in. Also you will have a longer blast of high pressure air (cfm) available for power tools. If you try to use an impact gun on a small tank, it might run for a few seconds and then there won't be any air available until it recharges.

You should also know that if an impact gun is rated at 200 foot pounds, it will only deliver that if there is enough air to run the gun. A fully charged tank will remove a tough nut, but a partial tank can't do it.

My unit is an old Craftsman from the '70s. Nowadays, the oil bath type cost big bucks, but they are quieter. For normal consumer use, you could look for a used one, or Home Despot sells them for a reasonable cost. If you don't use it much and constantly check the oil, they will do well for you. Our Despot unit at work uses oil at an amazing rate. I have to fill the cylinder every week for medium duty use. Expect to pay $600 or more.

A true 5 HP will not be available in 110 volt. A true 5 HP machine will pull 27 full load amps at 220 single phase.
Ingersoll Rand makes a nice compact small 5 HP Model 2340L5 that is designed for the smaller user. You can see them at www.pumatools.com. There are also some higher volume single stage stuff available but right now with free freight IR is pound for pound the best deal going.
Tank size is not a large factor. The pump is the key. The tank is reserve air and can get you over the hump for short burst of high volume but once the pump comes on you can only get out what the pump can supply.
Buy a machine that produces more air than your largest tool and you will never have a problem.

Thanks baymee and green valley!

I really appreciate your comments and suggestions. Going from knowing practically nothing about air compressors to having some good basic knowledge and understanding makes me more confident in the decision I am about to make.

If I were a younger man, I would go for the gusto, but since I've probably only got about 10 years or so to go (one never knows), I'm going to opt for a medium priced unit. I'll take a look at that Ingersoll Rand unit you mentioned, green valley.

Again, thanks.

bbbbosox

I'm looking at a catolog selling a TestMark or Master Craft 10 gallon 6.9cfm at 40psi and 5.5 cfm @ 90psi. How can this unit be almost double the CFM's of any product on the market???

Here is a link that might be useful: 6.9 cfm @ 40psi... 5.5 cfm @ 90 psi