Single or Two Stage compressor

[Todd Leback]

I'm going to be upgrading my current spraygun to a gravity feed cup gun. I haven't picked out the gun yet, but it will most likely require around 11-14 cfm at 40 psi or so. I'm looking to invest in a 5 HP compressor, either 60 or 80 gallon, and am just wondering whether I should go with a single or two stage compressor, and what exactly the difference is between the two. The new compressor will be dedicated for the spraying only, so I won't be running any other air tools off it.

Thanks!

[Alan Bienlein]

This is the one I'm gong to be upgrading to. The selling point for me was the pump speed was a nice low 650 rpm, single stage that puts out about 19 cfm at 90 psi and the whole pump is rebuildable. http://www.eatoncompressor.com/catalog/item/504747/9379899.htm
290370

[Rich Engelhardt]

I'm looking to invest in a 5 HP compressor, either 60 or 80 gallon, and am just wondering whether I should go with a single or two stage compressor, and what exactly the difference is between the two. The new compressor will be dedicated for the spraying only, so I won't be running any other air tools off it.

Single stage will usually have greater air delivery (more CFM) and two stage will have higher air pressure (more PSI).

For most applications, you'll want more CFM.

Higher PSI only comes into play when you need to "fit" as much air as you can into a smaller container.

A 60 gallon tank will hold more air in reserve @ 175PSI than it will air @ 125PSI.

Reserve air can be a big deal for a body shop or some other commercial application where people share the compressor, you don't want people standing around waiting for the air compressor to build up pressure.
In a home shop, where you're the only one using the compressor it's not that big of a deal.


The new compressor will be dedicated for the spraying only, so I won't be running any other air tools off it.
Besides the expense, a 60 or 80 Gal compressor, w/all the plumbing & accessories is a significant drain on space and upkeep time.

Have you considered a turbine HVLP unit?

[Ronald Blue]

That seems like a high number for air consumption. What does the specific gun you are looking at say it uses? A two stage might be the answer as Rich said the higher pressure equates into more available volume available. I gather that you have another compressor already if you won't be running anything else off of it. Tie the two together maybe through a central regulator? I think one compressor that meets all your needs makes the most sense however. Maybe you can tell us more about your setup and needs. You would need a minimum of 3/8" line to flow that volume at 40 psi as well. Just my .02 worth.

[David Kumm]

I would say air sanders benefit from a two stage as the compressor runs a little less and sanders use lots of air. Spray not so much so less important there. You also need a dryer of some sort if you live in any humidity. Dave

[Matt Meiser]

Have you considered a turbine system instead of a dedicated compressor and conversion gun?

[Ray Newman]

Agree with the comments on the turbine systems. Purchased an Apollo unit more than a few years and have never regretted it. Very small and compact unit that does not take up much storage room in the shop. Over the last 20 + years the only maintenance on the turbine was new filters and on the gun I replaced a few seals.

[Jim Andrew]

I used to finish my own woodwork when I built a house, sprayed lacquer from Sherwin Williams, only had a 2 cyl portable compressor. Had to stop sometimes to let it catch up, but I could spray all the woodwork and doors in less than an afternoon. The old Campbell Hausfeld did a good job spraying, got a Sanborn and it did not.

[Jim Neeley]

Back to the OP's question..

I own an Ingersoll Rand (IR) 5-hp 60 gal vertical L2340 2-stage that produces 14.7 CFM at 175 psig.

The comparable single-cylinder model is the SS5L5 5hp 60 gal vertical single stage that produces 18.1cfm @ 90 / 15.5 cfm @ 135 psig.

For low-pressure applications (say 75 psi and less) there isn't a heck of a lot of difference between them, with the SS5L5 likely producing a little more air and the 2340 storing a little more such that it doesn't turn on and off as often. The other difference is if you are using air faster than the compressor can supply it, such that you must periodically wait for the compressor to catch up. In that case the higher pressure unit stores more "reserve air" before the pressure drops too low for the tool to work.

The major difference comes in when you move to high pressure tools, such as impact wrenches. In that case, my old compressor turned on at 90psi and off at 135 but a rusted on nut might take 120 at the tank to deliver enough air to the tool to break the nuts free. Thus sometimes I'd not have enough air pressure to break a nut loose even before the pressure in the tank dropped enough to turn on. To work around it I'd have to draw down the tank pressure enough to turn on the compressor and let it max out before using the wrench to successfully bust the nut.

It's not a big thing but when I decided to upgrade from a Cr*psman to an I-R I decided to move to the compressor I didn't think I'd ever outgrow.

Just my $0.02.. YMMV.

Jim

[John Downey]

This is the one I'm gong to be upgrading to. The selling point for me was the pump speed was a nice low 650 rpm, single stage that puts out about 19 cfm at 90 psi and the whole pump is rebuildable. http://www.eatoncompressor.com/catalog/item/504747/9379899.htm
290370

Man! That sounds like a great unit for the money.

[Peter Quinn]

Not sure what spray rig you are planning to use, most use a lot less than that compressor can deliver, so I'm thinking you are fine. As others have noted a single user not using air intensive tools, not so critical which unit you get. Try running two air sanders at once or a big impact, starts to matter. I'd look into an HvLP gravity or pressure pot system depending on your volume. For the price of gun and compressor you could buy a great hvlp turbine and be done with it, I went compressed air for spraying because I do use other air tools.