Compressor opinion

[lsrx101]

So, armed with information that I gathered here and from new units in the stores, etc. I went on my search for a suitable air compressor for my garage.
I was a Tech for about 25 years and never could afford a compressor at home, and never even learned how to properly spec one! Now that I have a "cushy" job in IT, I still can't keep my hands clean and I find that I still need a compressor for the garage.

I decided that I needed a 50gal tank or larger, 7.5CFM or more, at 3.5hp or better. 220V was the obvious choice, just for electrical efficiency. I won't be using any real "air hogs", just my 1/2" impacts, air ratchets, die grinder, butterfly, air chisel, blast cabinet,etc.

I found a used Campbell-Hausfeld (#VT558705AJ)
vertical on craigslist and will be checking it out on Sunday. It's 5HP, single stage, 125 psi max, 11.4 cfm @ 40 psi, 9 cfm @ 90 psi, and a 60 gallon tank. The owner places it at early to mid 90's manufacture, but he didn't buy it originally. Comparable new units are ~$800 and up, but the modern ratings seem to be fudged a bit.
At $350 it sounds good to me, as long as it's not worn out or obviously abused. It sounds like it will meet my needs just fine, with a some overhead in case I get silly and want to try my hand at some body work (DA, air file, air grinder, etc)
I would appreciate any opinions.

I wonder about the quality of this unit. I remember CH being a good name in air products, but many of the CH air tools that I see today in the Big Box stores strike me as downright offshore cheap.
Thanks for any feedback.

 

[Steve in Mi]

A real 5 HP motor will be rated 23 to 28 AMPS.

Here is a 4 HP CH that claims to have more output than the 5 HP one you mention.

http://www.tractorsupply.com/webapp...10551_10001_48802_-1______?rFlag=true&cFlag=1

BTW,

I won't be using any real "air hogs", just my 1/2" impacts, air ratchets, die grinder, butterfly, air chisel, blast cabinet,etc.

I consider the impact, die grinder and blast cabinet to be air hogs, just my humble opinion.

 

[Charles (in GA)]

BTW, I consider the impact, die grinder and blast cabinet to be air hogs, just my humble opinion.

I second Steve's opinion. I have a full seven and a half horse (7.5 hp) two stage compressor, rated at around 24 cfm and it runs alot to keep up with a blast cabinet. Does OK with a die grinder or DA sander, but anything smaller would be making it WORK!

Charles

 

[russlaferrera]

I concur with the above posters, on all counts.

Look up the CMF useage on the air tools and blast cabinet . Some exceed the compressor output.

 

[lsrx101]

Hmm. I guess I need to rethink the size of compressor that I need.
Thanks for the help guys. You probably saved me from making a mistake.

 

[lucasd2002]

IMO, if you are going to invest in a stationary compressor, you should find a 2-stage - seems to be the biggest performance increase and it keeps the air cooler than a single stage. That's my plan - but I will probably not get a stationary for a while.

 

[mikeyr]

I have to agree with all the above. 35+ years I bought a 4hp SEARS compressor, don't remember the amps but it was 220V, it ran for near 30 years with no problems. I finally wore it out by using my blasting cabinet. I went and purchased a 5hp SEARS unit, was surprised that it needed way less amperage yet had more horses, it was a pile of doo-doo, I returned it and bought a 6.5hp airless unit, loudest thing I have ever heard (ok not quite) and not just oiless, but also airless. What I learned is that SEARS plays games with their HP ratings, they rate their motors differently then the standard, that is how they get a 5hp motor that draws 17amps.

I gave up and spent the big bucks on a Champion 5hp, the thing is awesome, super quiet and puts out more air than my blasting cabinet can use even after I put in the larger cfm nozzle which dramatically improved my blasting. If you are joe homeowner playing in the garage occasionally, just about any compressor will do the job, if you are serious about playing in the garage budget a big boy compressor and you will never look back. Those compressors will last your lifetime and your heirs lifetime.

 

[goodfellow]

IMO, if you are going to invest in a stationary compressor, you should find a 2-stage - seems to be the biggest performance increase and it keeps the air cooler than a single stage. That's my plan - but I will probably not get a stationary for a while.

I wouldn't be so hasty in recommending a two stage. In fact two stage compressors are much less efficient than single stage units -- when you compare electrical power requirements and cfm. Higher pressure alone doesn't make the unit more efficient than a single stage.

The most efficient (high volume) compressors are single stage units. In most cases, we run air tools which operate between 80 and 100 psi. Anything over that limit is wasted energy because it takes a lot of power to compress air to 175psi. High effciency 110-125 psi single stage units can easily run to 30cfm, and do it with less heat and electrical power requirements.

Here is one example

http://www.eaglecompressor.com/air_compressor_model.php?recordID=979

 

[Charles (in GA)]

Ohhhhh.......... the ole two stage vs single stage argument again. Two stage is used for the simple reason that you can store more ENERGY in a given size of tank by upping the pressure. If you put a value on the energy stored in a 80 gal tank at 175 psi (typical two stage shut off pressure) a single stage at say, 130 psi couldn't hold a candle to it. To store the same amount of ENERGY at 130 psi would take a much larger tank. Usually, air is used in short sessions, hence the tank. If the tank isn't big enough to hold the necessary stored energy to do your job, then it is gonna run alot more cycles. Thats the problem with a single stage, the only useful stored energy you have is from about 100 psi up to the max of 130 psi, not much cushion, before it kicks in and runs again. The stored energy of a two stage is the difference between the same 100 psi and the max of 175. Lots more energy output per gallon of tank capacity that the single stage, before it kicks in again.

What it comes down to is that it may take more electricity to pump to 175 but you are storing more energy doing it, so the difference between the single stage and a two stage as far as total electrical usage vs energy output is a wash, its a matter of how you are using that stored energy.

Indeed, high volume, continuous run compressors are all single stage, because you are not STORING the energy, you are using it as you put it out.

Charles

 

[ScaldedDog]

While we're on the subject, if all else is equal, which is quieter, a single stage or two-stage?

Mark

 

[6768rogues]

Sears rates their 120 volt motors as peak horsepower, which is the amount of power when the motor is at a load causing it to stall. Of course, no one runs a motor that way, or it would smoke in short order. Check their ratings, they say "Peak horsepower". Industrial motors are rated in terms of continuous running horsepower, which is a much more usable number.
If I invented a 120 volt motor that developed 5 continuous running horsepower, I would be as rich as Bill Gates.

 

[Charles (in GA)]

While we're on the subject, if all else is equal, which is quieter, a single stage or two-stage?

Mark

Most noise from a compressor comes from the inlet filter. With everything else being absolutely equal, I would guess the two stage is louder, as it is pumping to a higher pressure, but that would be a minor issue.

Charles

 

[PxTx]

I have to agree the Champion compressors are great. They are USA made, make more cfm than all of the popular units in stores and typically run much quieter! One other item to consider is RPM. The Champion compressors run around 800 RPM!

I'll actually be at a show this weekend with the Champion rep. and will have more lattitude to be able to offer a screaming deal if anyone is on the bubble with buying a cheapo or a higher quality unit. I will be able to beat any internet price this week.

 

[arthur1920]

I wouldn't be so hasty in recommending a two stage. In fact two stage compressors are much less efficient than single stage units -- when you compare electrical power requirements and cfm. Higher pressure alone doesn't make the unit more efficient than a single stage.

The most efficient (high volume) compressors are single stage units. In most cases, we run air tools which operate between 80 and 100 psi. Anything over that limit is wasted energy because it takes a lot of power to compress air to 175psi. High effciency 110-125 psi single stage units can easily run to 30cfm, and do it with less heat and electrical power requirements.

Here is one example

http://www.eaglecompressor.com/air_compressor_model.php?recordID=979

the link shows a "30cfm" compressor that is 7.5 hp. It doesn't say SCFM which I thought was what you should always compare. The 5 hp model elsewhere says 12.2 CFM.

 

[bochnak]

Sears rates their 120 volt motors as peak horsepower, which is the amount of power when the motor is at a load causing it to stall. Of course, no one runs a motor that way, or it would smoke in short order. Check their ratings, they say "Peak horsepower". Industrial motors are rated in terms of continuous running horsepower, which is a much more usable number.
If I invented a 120 volt motor that developed 5 continuous running horsepower, I would be as rich as Bill Gates.

I bought an oil-less vertical (120V) 22gal compressor from Sears in the mid 90’s. Max psi is 130. It reads 5HP on the plastic cover. The label with all the electrical info. says amp draw is 7.5. That equates to 1.2HP!!!!!! I didn’t know any better because I was young, about 15 years old. This compressor has served me well, and hope to upgrade in the next few years.

FWIW, I just received the new Sears catalog and all their compressors seem to have real HP figures on them. Or at least not as inflated as they once were.

 

[rburke65]

HUGE difference between an oil-less and a good 2 stage. I have both. The oil-less 20 gal.?? and i think it is rated a 3 HP, is so noisey, I COULD NOT HEAR MYSELF THINK!!!!!!!! But the new Champion 5hp, 2 stage, 805 rpm, oh so quiet!! We were talking, just like I am talking to you now (while we were leaning on it), carrying on a normal tone conversation. Hard to believe the difference. And that is just the noise factor, to say nothing of the output difference.