I am getting my son an air compressor as a gift and need some help. He needs/wants one with the following specs–5-6 hp minimum, 240 v., 175 psi, 60 gal vertical tank. I know nothing about these things so have several questions.
What are the good brands (I’d understood DeVilbis or Campbell-Hausefeld are good??)? What should I expect to pay? Lowes carries the ‘Kobalt’ brand and Home Depot carries ‘Husky’; are either any good? The note his wife gave me also said “twin cylinder to 175 psi”. Not sure what that means. Is there anything else I should be considering?
I’d appreciate any help you can give me. Thanks in advance.
Replies
DP,
From the specs you are quoting, it sounds like someone has been reading off a Craftsman compressor. You need to provide some additional information to get a constructive answer. What will the compressor be used for? Obviously as large as it is and requiring 240V, it isn't something he is taking to a job site.
The major specification to look for is the volume of air supplied at a set pressure, or 4.6 CFM at 90 psi. That spec will tell you which air tools you can run off the compressor. The higher the CFM at higher pressures allows you greater flexibility in tools. Of course, the higher the CFM, the greater the $$$.
He's an auto mechanic and would be using those type air tools. He does work at home and wants this for his personal set up there. As you can tell I am in way over my head in this area so I appreciate the help.
Since your son wants the Comp for Mechanic - duty, that lets you know what you'll need to get. Mechanic Air tools are much more demanding on CFM and Duty rating of Compressors than typical Carpenter uses. Even standard Air Wrenches, Impact wrenches will pull 5-10 CFM to use, and under load, they can run up to 15+ CFM. Throw in Air sanders, drills, etc, and you can easily run up to 20 CFM for sustained use.
You'll be wanting to look at a minimum of 60 gallon storage tank, with 80 gallon being the optimal "medium" size for his use. The two-stage arrangement is not because he'll need 135+ PSI, it's so that the storage tank optimizes the amount of air stored.
I'd stay away from house brands unless you know the OEM. Ingersoll-Rand is a great brand to use use for this application. Plan on spending $750-1200 for this unit, unless you can get one on clearance (like the unit mentioned at Sears) or lightly used.
as I understand it, many of the "leading" brands are cutting corners, eg. I hear IR is putting what is really a 3.5hp & raising the rpm of the motor to call it a 5 hp. motor wears out long before the pump. I hear puma: http://www.pumaair.com.tw/english/index.php3is good, also Saylor-beal is a cadillac......still making them the old way, but you pay for it. Puma $$ is prob. the way I will go when I upgrade.
The "twin cylinder to 175psi" is the killer (price-wise). That indicates he'd like a two-stage compressor, which adds at least a couple hundred bucks to the price.
A couple weeks ago I drooled over an Ingersol-Rand compressor on closeout at Sears: 5hp, 2-stage, 175psi, 80 gal. tank, around 15.5 cfm at 40psi & almost the same volume at 90psi. Normally $999, on sale for $637.
The big decisions on a compressor are:
* 1 or 2 stage - 2-stage gives higher pressure, plus higher output for given motor size (efficiency) Most of these I've seen would run in the $600-$1000 range, where the single-stage units in this basic spec range run $400-$600.
* cfm (cubic feet per minute) required. Painting, sandblasting or constant use of air tools requires faily high cfm requirements. The above mentioned IR unit, at 15+ cfm, would have adequate capacity for just about any homeowner application I can think of. When I get around to getting one (I should be finished with my garage in the springtime) I'll probably settle for one in the 9-12 cfm range.
* oil lube or oil-less. Oil-less are generally louder, shorter-lived. I don't think you'll find an oil-less 2-stage comp.
* Tank size - larger tank allows longer intervals between pumping cycles, and can somewhat make up for lower hp/cfm output.
Very few people really need pressures over about 120psi. My dad notices it when he's filling his truck tires to 100+ psi, but for most applications you're regulating down to under 100psi anyway. Most manufacturing plants run about 90psi throughout the shop.
Can't say too much about different brands - they all have their proponents and detractors. Ingersol-Rand has been making them for a long time, mostly higher-end units. Campbell-Housfeld is a big name, but they're making a full line of them, and I'm not sure their consumer-grade units are any better than a lot of the other house brands (I'm guessing most of these units are pretty much the same)
Don
Very few people really need pressures over about 120psi. "
Don,
True, but all two stages I've seen have 175PSI as the default pressure. Could always be lowered, but why?
WSJ
True, but all two stages I've seen have 175PSI as the default pressure. Could always be lowered, but why?
Raises the cfm production. I run my IR at 130 and added an 80 gal tank to make up for the storage loss. Unless you're doing a lot of sandblasting (I was) or some other high volume use, not much point.
PAHS Designer/Builder- Bury it!
Edited 12/8/2005 8:13 am ET by VaTom
Raises the cfm production. .............. Unless you're doing a lot of sandblasting (I was) or some other high volume use, not much point."
VA,
Point is that they don't loose their efficiency the way a single stage does at higher (above 40 PSI's) pressures, so you can cram more air into a smaller tank using less power and space.
WSJ
DP,
Sounds like he want's a serious compressor, not a toy. DeVilbis or Campbell-Hausefeld are pretty good values. Stay away from anything Sears. HP #'s are grossly overrated. Ingersol Rand's are excellent, but pricer. I have an 80 gallon 7.5HP DeVilbis 175 PSI (two stage), and it keeps up with any tool I have, and I have never had a problem with it in 10 years.
Don't confuse two stage (twin cylinder) compressors with multi cylinder, single stage compressors, the latter loose their efficiency quickly above 90PSI (just look at the CFM #'s at various PSI's). Pretty much all two stage compressors have sleeved cylinders, so whether made of aluminum or iron is a moot point.
WSJ