[JamieK]

Hi,

I need opinions on a couple of air compressors. I've read back through the archives and learned a lot about air compressors. Basically, buy the biggest as possible. The most I'll be doing is some paint and body work and light sandblasting. These are the two compressors I've narrowed down to...

http://www.mytscstore.com/detail.asp...27105&x=11&y=9

or

http://www.mytscstore.com/detail.asp...productID=9181

Is the 80 gallon too big, or is there such a thing? Will I be able to get parts for the FarmHand in the future? The pump is a Cambell Hausfeld.

All opinions welcome.

Thanks,
Jamie

[OneMoreTime]

If you compare the CFM ratings the larger one puts out significantly more air..for any sandblasting you will like that..and lets face it one of those is about a once per lifetime deal for most guys so you will be using it long after you forgot what you paid for it..So I would reccommend the larger one..Now the smaller one of the two will probably work fine if the extra money is an issue..

Just my thoughts on this one..

Sam

[Kampr]

Out of the two I'd definately get the Ingersoll Rand compressor . You could go someplace else and get a two stage compressor in the price range of the Ingersoll Rand.

Danny

[schnitz]

Sam pretty well nailed it on needing all the CFM for sandblasting (and I mean any sandblasting). A buddy used to work where they had a huge compressor (concrete readi-mix plant where it had to also provide air for a full shop) and even it would show a problem keeping up with a sandblast unit. CFM from a compressor is like amp ratings on power tools. Higher ratings are the ticket to happiness with your tool.


In a while, Chet.

[JamieK]

Whats the difference between single stage and two stage. What does the extra "stage" do?

Jamie

[russlaferrera]

The 2nd stage compresses the 1st stage to get higher pressure.

Single stage compressors max out at 150 psi. A two stage goes to 175psi range or higher.

[oldred]

Of the two the IR is the better choice however that 18.1 CFM rating is more than a little suspicious. That is good outfit, well built and will last a long time but about 14-15 CFM is probably closer to the truth for 5 HP and a single stage pump. A two stage pump will run cooler, quieter and put out a bit more CFM for a given power rating due to it's more efficient design. A single stage pump with multiple cylinders will compress the air equally with each cylinder and each cylinder will pump the air directly into the tank. A two stage pump uses cylinders of differing size so that the primary, larger cylinder, does not pump directly into the tank but directs the air through a precooler and into a smaller cylinder which will then boost the pressure into the tank. The Ingersoll is well worth the extra cost and should produce enough air for most small shops but whoever came up with that 18.1 CFM figure must have rolled one out of the wrong bag

[JamieK]

Thanks for the replies so far. I'm leaning toward the IR. One reason is thats its a brand name and I "should" be able to get parts for it 10+ years from now. (I hope. My neighbor can still get parts for his 20+ year old Speedaire). It's physically bigger than what I wanted (80 gallon vs 60 gallon tank), but I'll just have to make space.

My next question. What would be the main purpose of having a two-stage pump putting out 175+ psi? All the tools I see are rated at 90 psi, or at most, 125 psi. What would I need 175 psi for?

Thanks again for the advice. BTW, the IR 18.1 cfm has some sort of ISO certification with it. It may not mean anything, but at least it sounds good

Jamie

[OneMoreTime]

I have used one tha tput out 175 psi and somewher in the area of 22-25 cfm..nice unit but we were using a 1" drive impact to service the tires on semi's for home and small shop use the IR should do just fine..and if you are somewhat organized the only blasting one needs to do is some spot blasting here and there..

Sam

[oldred]

Not sure what the ISO certification is for in this case but I doubt they certify the CFM output on that thing. There is a certain amount of energy stored in any given CFM@PSI so theoretically a 5HP motor could produce X amount of CFM@90 PSI assuming 100% efficiency, not sure exactly what X amount would be since a 100% pump does not exist so there was never (for me) a need to know. I do know that single stage pumps are on the low side of the efficiency range and having tested a great many different motor/pump combos for flow over the last thirty years I know that about 15 CFM is about the max for a 5HP single stage combo, with a two stage fairing a little better and a rotary pump fairing a lot better. The compressor companies are WELL known for being extremely reckless with the truth, only recently being more honest about HP ratings because their butts were hauled into court in a class action law suit. We have been exposed to nonsensical figures for so long that when we see honest numbers they seem kind of small but I can assure you that 14-15 CFM is a very respectful number. Most outfits try to make their numbers look as attractive as possible for obvious reasons but to arrive at 18.1 CFM@90 PSI in this case took some very optimistic calculations.

Having said all that I think if you buy that Ingersoll and take proper care of it you will be very pleased with it --For a LONG time!