Air Compressors -- single vs two stage

[Dan Case LR]

I understand the operational differences between single-stage and 2-stage compressors, and the reasons why 2-stage compressors used in large, multi-user shops. My question is this: When does it make sense for a one-man woodshop to use a 2-stage stationary compressor instead of single-stage? Where there are single and two-stage models available at the same price point, how much difference does it make?

Thanks!

D.

[Brad Shipton]

It really depends on what you plan to use it for. If you plan to use any air tools like a sander, the minimum will likely be a two stage compressor. An air sander can take up to or more than 12 cfm. When I was a kid we tried sanding down a car with less, and I can remember how much of a nuisance it was to constantly be waiting for the compressor. A buddy tries to use his plasma cutter with too small a compressor, and when I watch it looks annoying.

I was debating this as well about three months ago. I added a CNC that needs air for a variety of aspects and I was trying to decide if I needed to spend the extra on the two stage 80 gal. I was convinced to buy the two stage and I am glad I did. If you are using the compressor for your run of the mill handyman tasks, then the extra CFM will unlikely be necessary. It really depends on what you intend to use it for. Some of us hobbiest's or one man shops have similar needs to the commercial shop, but the machines run 1/3 the time (or less). Commercial shops buy much heavier made compressors. I priced out a few of those, and quickly decided on an import.

[Joe Jensen]

With the same HP a single stage compressor will make higher CFMs but at a lower peak pressure. Most single stage compressors have a max pressure of 100psi. Dual stage is required to generate higher pressure. But a single stage with higher pressure will make lower CFM. Air sanders and spray guns need less than 100 psi so a single stage will make more air than a 2 stage. Air impact wrenches require 120 PSI or more. For really big impact wrenches they need 150-175 psi.

I have an industrial 2 stage because that's what I got a great deal on. I do use an impact wrench maybe twice a year so I get some value. I have my compressor pressure switch set to cut off at 150 psi as I never need more than that.

Here is data from one industrial manufacturer for three versions of their 5HP compressor.
115psi - 20.4cfm
150psi - 17.5cfm
175psi - 14.8cfm

[Albert Lee]

The pneumatic sander use a lot of air. I have a Festool LEX3 and it uses 10-11 CFM. you need a 20-24 CFM compressor to run it. not sure if 24 CFM is available in single stage compressor but unless you have a power issue, I am yet to see someone with a problem of "my compressor is too large"

[Martin Wasner]

I am yet to see someone with a problem of "my compressor is too large"

Bingo.

I currently have a 5hp two stage and it was incapable of keeping up with two air sanders. It does okay with one, but you're still running it pretty hard. I'm hoping by the end of the month to order up a new compressor. I'm looking at a 15hp screw type, it's 49 cfm at 145 psi, and hopefully I won't need anything larger than that for a long, long time. Air sanders are hogs, basically take a 1/4" and whatever it is capable of flowing is what you need. Depending on the cnc, they can use a lot of air. I know the one I'm looking at needs something crazy like 15.9cfm at 125psi.

Most stuff doesn't burn up that much air, and if you're by yourself the draw isn't that great. Take whatever your largest user of air is and add another arbitrary percentage you feel good about and you should be set.

[Ken Fitzgerald]

As Brad stated, it depends on one's individual use. I use a air sander for my turnings. Though I have a "5hp" single stage with a 26 gallons tank, I do have to periodically wait on the air pressure to build up.

[Dan Case LR]

My biggest air hog is a sander that's spec'd at 8CFM@90PSI. Depending on which multiplier you use, I need a compressor capable of 12-16 CFM at 90PSI. Most of the entry level (5HP 60 Gallon) 2-stage stationary units are rated around 15 CFM@90-100PSI, so they'd do the job, at least for now. I'm also looking at a 6.5HP 60 Gal single-stage that's rated 19.5CFM at 90PSI, at the same price point as the entry-level 2-stage. Assuming the numbers are reasonably accurate (reliable manufacturers, so that shouldn't be an issue), is there any good reason for one over the other? I don't see myself needing more than 100PSI in the future.

Thanks!

D.

[David Kumm]

You want to look at the duty rating of the compressor, particularly if single phase. Last thing you want is a lot of start and stop. Two stage reduces that and the down time also allows the air to cool more in the tank. If you run in humid times you need all the help you can get or the tools will spit water unless you put a dryer on it. A pump with more displacement that runs slower 600-900 rpm vs 1000-1200 helps too. Most current compressors undersize the pump and run fast vs the other way around. Dave

[Mike Cutler]

I understand the operational differences between single-stage and 2-stage compressors, and the reasons why 2-stage compressors used in large, multi-user shops. My question is this: When does it make sense for a one-man woodshop to use a 2-stage stationary compressor instead of single-stage? Where there are single and two-stage models available at the same price point, how much difference does it make?

Thanks!

D.

When you need the increased pressure at the point of service. This is of course tool specific.
CFM, delivered, is CFM delivered. The tool doesn't know whether it comes from a one, or two, stage air compressor. One big problem with my statement, is that very few manufacturers will spec the CFM delivered at tank discharge. Most give you CFM "displaced", which is meaning less.
Higher discharge pressure do equate to higher flow rates at lower pressures, but the tool will use what it needs. it's a matter of the compressor keeping up. The two stage is a higher pressure output machine, all things being equal.
I personally would wonder how/why a two stage compressor is selling for the same price as a single stage.

If you haven't already, check out Rolair's line of compressors. They are spec's in discharge CFM, and displaced CFM. They also come with true HP rated, continuous duty, motors. They make some nice units. I have two.

[Dan Case LR]

If you haven't already, check out Rolair's line of compressors. They are spec's in discharge CFM, and displaced CFM. They also come with true HP rated, continuous duty, motors. They make some nice units. I have two.

I have a Rolair on my short list -- the V5160PT03X, 5HP single-stage with 60 Gal tank. Delivers a little over 16CFM@90PSI. Not a lot of bells and whistles, no extended warranty hype designed to sell maintenance kits and worded in a way that doesn't really cover anything, just an honest 5HP compressor. At this end of their product line, it's likely to use some offshore components (like everyone else does) but after researching Rolair I expect that they're a bit pickier about those parts than some companies, because I haven't yet found much in the way of negative feedback on the company or its products. Most of the comments have been things like positive experiences with warranty issues, good customer service, and 'you oughta check out Rolair before you decide.' Companies don't get reputations like that by chance. They earn them.

And the one I'm looking at isn't the most expensive one on the list, either. One of the official online sellers has it for $999 with free shipping including liftgate. It has possibilities!


Thanks!

D.

[Brad Shipton]

I think David's comment about duty cycle is important. I wish I could have afforded a heavier compressor. The starters on all of the lower end imports you find at places like air compressor direct seem cheap. I cringe each time I hear my compressor start at 135psi. We measured the start up amps and it draws a slightly over 30amp each time it starts; whereas about the max we could create for my 5hp DC was about 7amp or so. I have read quite a few stories about guys having to repair the electrics on their compressors.

[Mike Cutler]

I have a Rolair on my short list -- the V5160PT03X, 5HP single-stage with 60 Gal tank. Delivers a little over 16CFM@90PSI. Not a lot of bells and whistles, no extended warranty hype designed to sell maintenance kits and worded in a way that doesn't really cover anything, just an honest 5HP compressor. At this end of their product line, it's likely to use some offshore components (like everyone else does) but after researching Rolair I expect that they're a bit pickier about those parts than some companies, because I haven't yet found much in the way of negative feedback on the company or its products. Most of the comments have been things like positive experiences with warranty issues, good customer service, and 'you oughta check out Rolair before you decide.' Companies don't get reputations like that by chance. They earn them.

And the one I'm looking at isn't the most expensive one on the list, either. One of the official online sellers has it for $999 with free shipping including liftgate. It has possibilities!


Thanks!

D.

It definitely has strong possibilities. That's one of the Rolair models I have. ;) In fact, I only got it last week, and I am still in the process of getting it plumbed up. I wanted something bigger to run impact wrenches and spray guns. I also have a Rolair JC10.
If you want to know anything about the V5160PT03X, let me know, and I'll try and answer as best I can. A few thing to know right off the bat. The parts are sourced overseas and the unit assembled in Wisconsin. The motor is a WEG motor, made in Brazil. The output connection can be either 1/2" NPT, or 3/4" NPT. There is 3/4"-1/2" NPT reducing bushing on the outlet. You'll need a 1/4" male to female 90 degree elbow for the drain connection to bring it out.

[David Kumm]

Don't rule out a used compressor. The old Quincy QR 325 are common and by far the best designed and quality available. Pretty common in the 750-1000 range for a good running with a decent tank. The pumps are so good that with minimal skills, you can clean up the valves, ( they will be rusty ) change the oil, and have a great 16 cfm compressor that runs with a pleasing sound and will outlive us all. I've rehabbed a couple and no big deal and those still running don't need much work. The new ones are nothing like the QR. Just another option. Dave

[Kelby Van Patten]

I picked up a Kobalt 5 HP compressor from Lowes almost 10 years ago. I used it in my hobby shop to run a Dynabrade pneumatic sander. It held up just fine. Despite what some of the experts out there will tell you, I never had to wait for it to build up pressure. It did, however, run nearly 100% of the time when I was working with the sander, and it died about 1-1/2 years ago. I do think that I overtaxed it, but a hobbyist in a one-man shop isn't going to overtax something like that to the point you can't get a decent working life out of it.

When it died, I replaced it with a Quincy 2-stage. It runs very quiet (I could run it without hearing protection if I were so inclined). It also cycles off a lot of the time, so it isn't having to run constantly when I'm sanding. That's partly because it fills up the tank faster than the Kobalt, and partly because it fills the tank to 150 psi.

It adds a lot more moisture to the tank, so a dryer is a must.

I like having the Quincy. But truth be told, it's more than $1k extra, and a guy could easily make do with something like my old Kobalt and spend the leftover thousand bucks on another tool. For me, though, I had enough in my budget to get it, I like the fact that it is much quieter, and I am hopeful that the Quincy will be a lifetime tool rather than an 8-year tool.

[Dan Case LR]

It definitely has strong possibilities. That's one of the Rolair models I have. ;) In fact, I only got it last week, and I am still in the process of getting it plumbed up. I wanted something bigger to run impact wrenches and spray guns. I also have a Rolair JC10.
If you want to know anything about the V5160PT03X, let me know, and I'll try and answer as best I can. A few thing to know right off the bat. The parts are sourced overseas and the unit assembled in Wisconsin. The motor is a WEG motor, made in Brazil. The output connection can be either 1/2" NPT, or 3/4" NPT. There is 3/4"-1/2" NPT reducing bushing on the outlet. You'll need a 1/4" male to female 90 degree elbow for the drain connection to bring it out.


Nothing inherently wrong with offshore components if they're good offshore components. I'd still rather have a Baldor, but if Rolair chose the right WEG motor for the job, I have no problem with that. The determining factor isn't where the components came from, but that the assembling manufacturer chose those components well. I'd still rather have a Baldor, but not bad enough to pay for one in this case.

Do you know who made the pump?

One other question--a minor point--where on the tank is the output connection? I can't tell from the pictures I've seen.

I'm also curious about how loud it is in actual operation.

Thanks!

D.

[Joe Jensen]

I think David's comment about duty cycle is important. I wish I could have afforded a heavier compressor. The starters on all of the lower end imports you find at places like air compressor direct seem cheap. I cringe each time I hear my compressor start at 135psi. We measured the start up amps and it draws a slightly over 30amp each time it starts; whereas about the max we could create for my 5hp DC was about 7amp or so. I have read quite a few stories about guys having to repair the electrics on their compressors.

I got a great deal on an old Quincy. I went to the local dealer for some parts and chatted them up about how to test. They said that whenever they evaluate a compressor line to sell they get a loaner from the manufacturer. One Friday night they fire it up and open the drain cock enough so the pump works against a nearly full tank but it runs continuously until they come in on Monday morning. The guy I was chatting with said that's how they know if a compressor is industrial or not. He said none of the Chinese made pumps had survived a weekend torture test.

[Dan Case LR]

Don't rule out a used compressor. The old Quincy QR 325 are common and by far the best designed and quality available. Pretty common in the 750-1000 range for a good running with a decent tank. The pumps are so good that with minimal skills, you can clean up the valves, ( they will be rusty ) change the oil, and have a great 16 cfm compressor that runs with a pleasing sound and will outlive us all. I've rehabbed a couple and no big deal and those still running don't need much work. The new ones are nothing like the QR. Just another option. Dave


I'd love to find one of those older compressors. They're awfully scarce in my neck 'o the woods. A lot of people that have them know better than to sell them. Once in a while one will show up that's 3-phase, but the cost of changing motors makes it prohibitive. I've also seen a few compressors that have been sitting in an open barn for 30 years, haven't been run in 40, and given our always-humid climate here are solid rust and rot. And the seller thinks they're made of platinum. :)

D.

[Albert Lee]

Nothing inherently wrong with offshore components if they're good offshore components. I'd still rather have a Baldor, but if Rolair chose the right WEG motor for the job, I have no problem with that. The determining factor isn't where the components came from, but that the assembling manufacturer chose those components well. I'd still rather have a Baldor, but not bad enough to pay for one in this case.

Do you know who made the pump?

One other question--a minor point--where on the tank is the output connection? I can't tell from the pictures I've seen.

I'm also curious about how loud it is in actual operation.

Thanks!

D.


Here is my Chicago Pneumatic CPRS10500 in operation. The brand started as American, bought by AtlasCopco in the late 80's, and the unit is made in Italy. probably outsourced. 10hp, 43CFM


https://youtu.be/xMpRpo6GmJ8

[Mike Cutler]

Nothing inherently wrong with offshore components if they're good offshore components. I'd still rather have a Baldor, but if Rolair chose the right WEG motor for the job, I have no problem with that. The determining factor isn't where the components came from, but that the assembling manufacturer chose those components well. I'd still rather have a Baldor, but not bad enough to pay for one in this case.

Do you know who made the pump?



One other question--a minor point--where on the tank is the output connection? I can't tell from the pictures I've seen.

I'm also curious about how loud it is in actual operation.

Thanks!

D.

Dan

I don't know the manufacturer of the pump. It's not labeled. Possibly a call to Rolair could answer that one.

Th outlet connection is on the right side of the tank, 41" off the floor. It's an 1/2" NPT connection, and comes with a 90 degree ball valve. The actual connection is a 3/4"- 1/2" reducer. I took out the 1/2" fittings and valve and replaced them with 3/4" fittings and valves. I'll be running 3/4" pipe through the garage.so I started it off that way.

It's not as loud as many compressors I've been around. My wife hung out when I turned it on for the first time, and we did have to talk loudly over it, but she didn't run out of the garage plugging her ears with her fingers.;) We were in the open garage with no hearing protection.
It's loud, just not Banshee screaming loud. I think the 70-73dB value I've read, seems about right. My JC10 is 60 and that's right at normal conversation value.
I have one of those Porter Cable pancake compressors, and it's obscenely loud!

Good luck with your selection.

[Rich Engelhardt]

I am yet to see someone with a problem of "my compressor is too large"It's way more common that you think....
When I sold compressors, I'd run into that all the time.
Granted, it's not as common as the reverse - having too small a compressor, but, it's still a common thing to run into.

I'm a huge believer in the small ultra portable class of compressors - the 1 to 3 gallon, 1/3 HP to 1 HP.
They are perfect for those many times just a little bit of air is needed.

[Ken Combs]

One overlooked benefit of a 2 stage is the higher storage pressure provides a capacity storage buffer. You can run a tool for longer before the pump has to restart. 80 gallons of 150-175psi air is a lot more that the same 80 gallons at 100-110psi. since you almost never use tank pressure but regulate down to whatever the task requires, you effectively have more that the rated flow available for use, for a while anyway.

That can make a big difference in the units' ability to keep up with some tasks. A sandblast cabinet cleaning small items is one example. They use a lot of air, but starting with a full tank, you can blast for long time before the pump can no longer keep up. And, in my case, changing parts allows it to catch up and I can blast continuously.

Same holds true when finishing a bunch of cabinet doors.

[Dan Case LR]

Thanks, everyone for your input and comments. After waffling around between single and 2-stage and two smaller units combined vs one bigger unit, I think I'm close to pulling the handle on a new compressor. And frankly, I've surprised myself. Unless someone comes forward with a compelling argument for a different direction (or I find an older compressor for sale locally) in the next day or two, I'm going to order a Quincy QT-54. It's their bottom-of -the line for two stage models, with a 5HP Baldor motor turning an American-made compressor pump, and while at $1299it's not the cheapest 2-stage around, I think it's a better long-term investment. If I buy Quincy's maintenance kits (oil, filters, etc) the 1-year warranty becomes 2, and the pump warranty becomes 3 years. And hey, I'm gonna buy that stuff anyway, right?

So, anyone feel compelled to talk me out of the Quincy? I'm listening!

D.

[Ken Fitzgerald]

I know a lot of guys who will talk you INTO buying a Quincy!

It sounds like a good plan to me.

[David Kumm]

Most compressors companies, Quincy, Champion, Curtis, have three levels. The lower levels are all pretty comparable and I'd likely take Quincy. The middle level will run about $500 more and the top level pressure lubed will add another 1000. The Quincy QR will be still higher but they are a better build. Saylor Beall in Michigan also makes a very good unit in the mid level splash series and slightly higher pressure lubed series. Dave

[Albert Lee]

Thanks, everyone for your input and comments. After waffling around between single and 2-stage and two smaller units combined vs one bigger unit, I think I'm close to pulling the handle on a new compressor. And frankly, I've surprised myself. Unless someone comes forward with a compelling argument for a different direction (or I find an older compressor for sale locally) in the next day or two, I'm going to order a Quincy QT-54. It's their bottom-of -the line for two stage models, with a 5HP Baldor motor turning an American-made compressor pump, and while at $1299it's not the cheapest 2-stage around, I think it's a better long-term investment. If I buy Quincy's maintenance kits (oil, filters, etc) the 1-year warranty becomes 2, and the pump warranty becomes 3 years. And hey, I'm gonna buy that stuff anyway, right?

So, anyone feel compelled to talk me out of the Quincy? I'm listening!

D.

Dont buy cheap tools...

Poor quality remains long after the sweetness of low price is forgotten

[Joe Jensen]

Thanks, everyone for your input and comments. After waffling around between single and 2-stage and two smaller units combined vs one bigger unit, I think I'm close to pulling the handle on a new compressor. And frankly, I've surprised myself. Unless someone comes forward with a compelling argument for a different direction (or I find an older compressor for sale locally) in the next day or two, I'm going to order a Quincy QT-54. It's their bottom-of -the line for two stage models, with a 5HP Baldor motor turning an American-made compressor pump, and while at $1299it's not the cheapest 2-stage around, I think it's a better long-term investment. If I buy Quincy's maintenance kits (oil, filters, etc) the 1-year warranty becomes 2, and the pump warranty becomes 3 years. And hey, I'm gonna buy that stuff anyway, right?

So, anyone feel compelled to talk me out of the Quincy? I'm listening!

D.
Buy once cry once, good call...joe

[Mike Cutler]

I'm going to order a Quincy QT-54. It's their bottom-of -the line for two stage models, with a 5HP Baldor motor turning an American-made compressor pump, and while at $1299it's not the cheapest 2-stage around, I think it's a better long-term investment. If I buy Quincy's maintenance kits (oil, filters, etc) the 1-year warranty becomes 2, and the pump warranty becomes 3 years. And hey, I'm gonna buy that stuff anyway, right?

So, anyone feel compelled to talk me out of the Quincy? I'm listening!

D.

Dan

Quincy makes nice compressors.
You're getting a winner.;)

[Dan Case LR]

Dan

Quincy makes nice compressors.
You're getting a winner.;)


Yes they do.

I pulled the rope today!:D:D:D

D.