2 Air compressors vs 1 larger

Old 02-01-2017, 04:14 PM
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Default 2 Air compressors vs 1 larger

Looking for a larger compressor for my new shop.
It will see air ratchets, nibblers, air hammer, mild painting, med sized blast cabinet. So I was looking for a Horz 2 stage unit.
Problem is cant find one used, new would be 2000-2400 bucks.
I am seeing a ton of GOOD used med sized single stage for 200-300 bucks.
I could by 2 single stage and tandem them to get around 10-14 CFM @100
I could hard wire each to it's own switch, flip one on for general work, flip them both on for blasting.


thoughts?


Slack
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Old 02-05-2017, 10:45 PM
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Unless you want them fighting each other, you'd need to pipe them into a third tank via one way check valves.

Not worth the hassle.

I take it you are looking for professional grade?
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Old 02-15-2017, 11:06 AM
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I have a dual compressor, third tank setup, but its not needed to be done that way.

I use the third tank as an after cooler and since my main 5 HP units do not have after coolers. It also gives me extra air storage.

Originally I had them all plumbed into one manifold but had condensate problems, so I forced the air through the third tank which solved the problem. Now my coalescing filter is little more than an air filter, as I never really get any water out of it. Maybe a few drops after the compressors have been running for 45 minutes.

I do suggest going with dual stage compressors. You put an air swivel on a air ratchet, at the end of a 50 foot hose, you are looking at close to 50 psi pressure drop. Your regulator would need to be set at 140. This is where dual stage usually kick on, about 140-145.

Having two means you can service one and still have another one functioning.

If you are buying a big industrial brand, go with a single 7.5 HP with after cooler.

Pay once, cry once!

Not too many people say I wish I got a smaller air compressor.

Last edited by md21722; 02-15-2017 at 11:08 AM.
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Old 02-15-2017, 11:31 AM
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Run a single compressor, then if down the line you need more volume you can always add an external tank.
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Old 02-19-2017, 06:24 AM
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My compressor is small 2hp and under 6 cfm self contained 5cu ft tank. But is was $175
Good for tires, blow gun, no good for air tools, consumed the avialable air too fast.
Air pigs on sale, added two 5 gal pigs for $60.
Now have some volume, can use the air tools in normal applications.
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Old 02-27-2017, 08:33 PM
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Lowes 60 gal single stage, 11.5 CFM @ 90 psi - now $449.00
2 of them would give me 23cfm at 90 psi.
looking at 2 stage compressors,, I would be in the $2200.00 + price range to crack 20cfm @ 90


Am I missing something ??
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Old 02-28-2017, 02:07 AM
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Originally Posted by Slackdaddy View Post
Lowes 60 gal single stage, 11.5 CFM @ 90 psi - now $449.00
2 of them would give me 23cfm at 90 psi.
looking at 2 stage compressors,, I would be in the $2200.00 + price range to crack 20cfm @ 90


Am I missing something ??
Its not that cut and dry. You will need to run a 3rd tank as blueridgemark had stated. You're going to need to consider the fittings as well as hard line/hose you use to connect it all. You can't just T off the 2 compressors together and expect to get the results you're after.

Also take into consideration the amperage needed to run two compressors off of the same breaker/outlet.
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Old 02-28-2017, 10:40 AM
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Originally Posted by LACK View Post
Its not that cut and dry. You will need to run a 3rd tank as blueridgemark had stated. You're going to need to consider the fittings as well as hard line/hose you use to connect it all. You can't just T off the 2 compressors together and expect to get the results you're after.

Also take into consideration the amperage needed to run two compressors off of the same breaker/outlet.
Yes, you can just T two compressors together. There is no "need" for a third tank.

Originally Posted by Slackdaddy View Post
Lowes 60 gal single stage, 11.5 CFM @ 90 psi - now $449.00
2 of them would give me 23cfm at 90 psi.
looking at 2 stage compressors,, I would be in the $2200.00 + price range to crack 20cfm @ 90


Am I missing something ??
Yes. You are going to have a lot of noise to deal with & I'm not sure you've thought out water control. Plus, single stage compressors are not ideal for air tools that require 90 PSI working pressure. Take your average air ratchet that has a swivel on the end. You need the regulator set around 130 PSI just so the tool sees 90 PSI when its working. This is where dual stage shine. They usually cut in at about 140-145 PSI. Those ones at Lowe's are generally set to cycle 90-135 so the hypothetical air ratchet will be down to 50 PSI working pressure by the time the thing cuts on.
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Old 02-28-2017, 11:26 AM
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As far as noise,, the single stage should be no louder than the 2 stage.
Unless the budget single stage is running at a much greater RPM to get those impressive CFM #s.
If the single stage is a 3750RPM and the 2 stage is a 1750 RPM, yeah they will be louder. BUt, then again they will be in a shed behind the garage, noise wont be an issue.


So I am down to will a single stage maxing out at 155 PSI run my tools.
Or how to cut the amount of drop in the lines?


Slack


Originally Posted by md21722 View Post
Yes, you can just T two compressors together. There is no "need" for a third tank.



Yes. You are going to have a lot of noise to deal with & I'm not sure you've thought out water control. Plus, single stage compressors are not ideal for air tools that require 90 PSI working pressure. Take your average air ratchet that has a swivel on the end. You need the regulator set around 130 PSI just so the tool sees 90 PSI when its working. This is where dual stage shine. They usually cut in at about 140-145 PSI. Those ones at Lowe's are generally set to cycle 90-135 so the hypothetical air ratchet will be down to 50 PSI working pressure by the time the thing cuts on.
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Old 02-28-2017, 02:35 PM
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The pump RPM is a bigger factor in noise, but generally speaking, pumps powered by 3450 RPM motors usually run faster than pumps powered by 1725 RPM motors. That's not always the case though. You can go buy a Quincy QT-5 with a 1725 RPM motor that turns near 1000 RPM or a Champion with a 1725 RPM motor that runs around 730-740 RPM.

In any case, since they are in a shed, and noise doesn't matter...

As far as lowering pressure drop, use the shortest hose possible with the least amount of fittings, using high flow couplers, ... The swivels themselves generally knock pressure down 15-18 PSI. They do make expensive swivels that only knock pressure down about 2 PSI but they are about $75 each.

The other problem with single stage pumps is that they slow down on CFM output past about 110 PSI. 20-30% drop in performance is not uncommon and it gets worse as the pressure goes up. Dual stage pump very linearly throughout the operating range. That's why you see single stage pumps rated at 40 and 90 PSI but good dual stage pumps are only rated at 175 PSI.

Dual stage pumps also tend to create drier compressed air than single stage, but once any of them have been running for a while, moisture is going to be a problem that you need to deal with.

This is where after coolers, auxiliary tanks, coalescing filters, refrigerated air driers, and desiccant filters come into play. What will meet your needs depends on how dry you need the air & the relative humidity in your area.
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