Looking for air compressor recommendations

[pjr710]

Hey guys, I'm asking here because I just read a very intelligent thread on here about air compressors.

I have to do a "walnut blast" on my engine, which removes carbon buildup on my direct injection motor's intake ports.

I don't have a good air compressor right now so I'd like to purchase one, and I would like to only purchase the right one .. one time.

I've been reading a ton about CFMs, PSI, etc and it's kind of a nightmare.

What sparked me to create this thread is the previous thread I was readying someone mentioned if you have an oil-less compressor go outside it's duty cycle it can overheat.

I DO NOT want that to happen.

Basically what I want is to get a somewhat affordable compressor that will allow me to walnut blast, but also run air tools if I wanted, like a ratchet, impact gun, chisel, etc.

At this point I'm not sure what matters most .. whether it's CFM, PSI, tank size, etc.

I know me personally it seems I would want something quiet, I would want something that doesn't have to recharge that frequently, etc.

The new bit of info about "over heating" I don't like because if oil units don't have this issue I may go with that instead.

Also I'm limited to 120v.

Any advice is MUCH appreciated.

 

[bsaint]

Look for something that draws 15 amps @ 120v.

 

[lbhsbz]

Look for something that draws 15 amps @ 120v.

Excellent advice. Ignore the HP rating on the sticker...look for the one that draws the most amps...which for a 120V unit will be 15.

 

[sberry]

First, what power you have available? It doesn't seem like blasting some intake ports would be a great job. You could slide by in this world with a 400$ comp draws about 15A @ 240v. A generic 2 stage might be 800 that uses the same power. A good standard 5 2 stage maybe in the couple thousand range and allows full work for a journeyman. Run any tool a guy wanted and do modest sandblasting.

 

[sberry]

The 12 ga garage did a good job with this. Jack spent about 400 on a new comp and put it in a closet. (As I recall it was him?). Makes 2 x the air of a 120 model with a little bigger tank. Also doesnt trip up a breaker and easy on the electric demand.

 

[hawkerxj]

Look for something that draws 15 amps @ 120v.

It would be good to have a 20 amp circuit if you are going to do that. I used to run a 15 amp compressor on a 15 amps circuit and spent alot of time walking over to the breaker box.

 

[sberry]

Whoops, missed the 120v part.

 

[CGT80]

You want all of the good with none of the bad and..............you can't have it!
You will want to read more about how cfm and psi works with tools and also about single stage vs. 2 stage.

Tools need a certain amount of volume (cfm) and need a at least a certain amount of pressure (psi) at that volume. Generally, higher pressure will provide lower cfm when dealing with small or single stage compressors. A 240v compressor may be rated at 9.6 cfm at 40 psi but only 7 cfm at 90 psi. Air tools generally need to have 90 psi while running. An air compressor that does not cycle until the tank drops to 90-100 psi is no good as you will have much less at your tool by time it turns on.

**** blast has three sizes of tips for their guns. The small set is around 10 cfm at probably 60-80 psi. I run the big ones that are 20-25 cfm.

A 120v compressor won't even make 10 cfm at 90 psi.

A big tank will provide a high cfm until the pressure drops, then it has to pump up. That is where the pump cfm comes in. If the pump is small, you will have to stop using air for the pump to catch up and refill the tank.

With a 120v compressor and many 240v small units, you will be able to blast for anywhere from 30 seconds to a minute or two and then you will need to wait for it to catch up.


All of this info is covered in many other threads on GJ and air compressor threads are very common.

I bought a used real 5hp 80 gallon 17.3 cfm at 175 psi compressor. It averages 20 cfm with the pulley I have on it, based on how fast it cycles and fills. I can blast with that large 20-25 cfm tip and it takes 3 minutes or more to drain the tank enough to cycle the compressor, then it catches up and rests for another 3+ minutes. Grinders, sanders, plasma table, etc. are no match.


In my opinion, anything less than 17 cfm at 175psi (two stage) is going to be a compromise. How much are you willing to compromise, or what is your budget for the buy it once compressor. The big compressors are less noisy, won't overheat, are built much better, but are very heavy and require at least a 30 amp 240v breaker. They are very expensive new ($1500 min to as much as $3500), but sometimes can be had for a few hundred dollars used. There are also plenty of used basket cases that could need minor repair or end up being junk......it is a gamble, but I did my homework on the one I wanted to purchase and then made the deal.


The higher the pressure in your tank, the more air it holds and the longer it will last. 175 psi is a lot more air than 135 psi, if the tank is the same size. It is better to have high tank pressure and run a regulator to get the pressure you need while the tool is running. A small cfm pump will fill a very big tank, but it can take 5-30 minutes to fill. When the tank is full, it will give you all the air you need and for a good amount of time, but when you run low, the pump will never catch up and you will have to stop working. A huge pump and tiny tank is the opposite. You don't want to run the motor many times per hour as it is hard on the motor. Factory built compressors usually hit a happy medium but a modified one may have an odd combo.


My big compressor takes 5.5 minutes to fill the empty tank but only 60 seconds to cycle when it gets low, and it usually doesn't run more than a few times per hour, unless I am plasma cutting or blasting. Big cast iron pumps don't get as hot or spin as fast as the little compressors, so they last longer and are quieter. An oil free compressor spins very fast and will run constantly for blasting. It takes a long time to kill one, even if you want it to die. LOL! What is not good for a compressor isn't always an immediate death sentence. They can hold up longer than your patience will while dealing with one that is too small.

 

[99LeCouch]

Oiled-pump 30ish gallon compressor is what you are after. Runs on 120v, and workable for small blasting jobs like your walnut shell blasting. I do a yearly spray of Fluid Film with a 30 gallon compressor, and it does fine. I'm not waiting that long for it to refill.

The other nice thing is those are semi mobile, so they can be wheeled out of the way. Nice with a smaller garage or awkward storage layouts.

 

[bdk1976]

I am a ********* diy'er and I would seriously consider farming that job out if my only option was a 120V compressor. Not only will you lack air, you will be fighting moisture as well.

 

[Citation]

Do you have two 120v circuits available? My garage only has 120v power but I do have 2 circuits so I can run two 120v compressors simultaneously. Once I get a few more changes made I'm going to plumb two compressors together. This should give me around 9 cfm combined. Most of the time I'll use my 20 gallon belt drive compressor but if I need more flow I can supplement the larger unit with my roofing compressor.

A 3hp, 60 gallon would be nice but it would also use basically all the power my garage gets and make running just about any other power hungry tool (shop vac, miter saw etc) impossible. The dual compressor setup let's me select when I use all the power for compressors vs only a portion. It also works since I already own the compressors.

 

[dnschmidt]

All of these threads sing the same song: "Money for Nothing" by Dire Straits. I want a 110V compressor that I can sand blast with. Well good luck. I've got a 5HP 2 stage Quincy two stage that I can't sand blast with for very long. It's the bare minimum to run die grinders and air sanders and just keeps up with my SATA spray guns. Apparently Mexicans aren't the only "dreamers."

 

[FSrepair&fabrication]

Youre not going to get a very powerful compressor that runs on 120v. However for most quickie jobs with basic air tools you could get by with a 30gallon craftsman or whatnot. If you want to blast youre going to have to step it up a bit. If electric is an issue, consider a gas powered wheelbarrow compressor. Stick it outside and tie it in to your electric compressor when you need more air. both running at once may be enough to do what you want.

 

[Citation]

All of these threads sing the same song: "Money for Nothing" by Dire Straits. I want a 110V compressor that I can sand blast with. Well good luck. I've got a 5HP 2 stage Quincy two stage that I can't sand blast with for very long. It's the bare minimum to run die grinders and air sanders and just keeps up with my SATA spray guns. Apparently Mexicans aren't the only "dreamers."

I don't agree that you need a 5hp 2 stage to do due grinders. Sanders would depend on the sander. My father was using a true 5hp 2 stage (Champion I believe) for many years. Things changed and when he went to set up a home shop to do similar work he was using a 30 gallon, ~8 cfm (per Speedaire's pump specs) compressor for a number of years. It handled his air hand tools (due grinders, right angle sanders, air drills etc) that he used for fabrication (thin wall, welded steel). It was very limited when sand blasting. He now has a low end 80 gallon 2 stage that is sufficient (not great) for his sand blast cabinet.

I think the point is there is a range of what can do the job. 5+ hp compressors are great but for many it's not a must have to do the job if space, budget, power etc prevent you from having one. What is harder is trying to help people understand the compromise they have to accept.

 

[Kaizen]

Op it can’t be done. I have a 500 dollar 11.5 cfm 60 gallon 220 volt and about another 300 bucks in water control and I get maybe 5-10 minutes of blasting out of it before I have to wait 12 min for it to get back up to pressure. Even my little air tools kill it. I didn’t listen when I asked this question years ago and learned my lesson. For the money I spent I could have had a nice 5hp one. Farm it out for 100 bucks.


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