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#1
Old 09-13-2010, 12:47 PM
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Pancake vs Twinstack air compressors

I am in the market for a portable air compressor, and these two types are the popular designs nowadays. I am looking for advantages and disadvantages of both.
#2
Old 09-13-2010, 01:12 PM
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I think it depends on what you intend to use it for. For the same specs, etc. the twinstack is more expensive, but usually has a few more features (two out flow connects, wheels for rolling vs. carrying) The twinstack is usually heavier.

For just having one in the garage for normal around the house use, I would go with a pancake, which is what I have. If you are building professional or are planning on using it regularly with a nail and staple gun for big projects, probably I would upgrade to the twinstack.
#3
Old 09-13-2010, 01:18 PM
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Pancakes are usually smaller and lighter. You can take one up on a roof with you, or carry it up scaffolding. You need shorter hoses if you bring it close to the work, but then you need a longer extension cord. Portability isn't a requirement for me, so I have a larger compressor with a 25 gallon tank. It is on wheels though. How portable do you need it? For lots of remote work a gas powered unit will be more useful.
#4
Old 09-13-2010, 01:39 PM
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I need one for general household use with brad nailers, flooring nailers, and framing nailers. I just sold my big 30 gallon one (inheirited) because it was too damn heavy and unwieldly to get near most areas where I needed to work. The one time I used it I had to set it up outside and run 50 feet of air hose through the window. Needless to say, this cannot be done on rainy or snowy days, and makes set-up a bit of a pain.

Other than multiple outflows, what are the advantages of the twinstack? Just the fact that the motor is more protected?
#5
Old 09-13-2010, 02:09 PM
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I would make sure the compressor you buy will deliver the CFM for the tools you will use. The smaller ones are fine for brad nailers but will not deliver enough CFM for a flooring nailer.
#6
Old 09-13-2010, 03:52 PM
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I used to own a pancake, but now have a twin stack. The pancake was oiless and the twin stack has a sump, so I expect it to last a long time. Twin stack is heavier by a significant margin, but easier to carry because it's narrower in one dimension.

It's a Hitachi.
#7
Old 09-13-2010, 04:52 PM
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Quote:
Originally Posted by GaryM View Post
I used to own a pancake, but now have a twin stack. The pancake was oiless and the twin stack has a sump, so I expect it to last a long time. Twin stack is heavier by a significant margin, but easier to carry because it's narrower in one dimension.

It's a Hitachi.
Is there anything special about the twin stack instead of a single tank? I don't have the need, my larger model is in the basement and I have a couple of hundred feet of hose. But now this thread has me interested in all the details.

Also, did the pancake fail on you? I'm leary of the oil-less concept, but I just put a little Mystery oil in everything anyway, and haven't had a problem. But nothing has had heavy use for a several years either.
#8
Old 09-13-2010, 08:26 PM
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In general the difference between the twin stacks is the twin stacks are oiled compressors. In recent years this has become less true however as a few companies have put out oil free twin stacks.

Only taking tanks into account no there is no fundamental difference between having a single tank vs a double tank. The just hold pressurized air. The total volume is the only important factor. And to the average user that's not even important.

What is important is the CFM the compressor puts out. The CFM needs to be more then any tool you intend to use with it.

Oil free vs oiled is another factor to consider.

Oiled compressors in general can produce more CFM as they are intended to run continuously to produce it on a job site it is not an issue to have an oiled compressor running most the day. They are built for that activity. Oiled compressors are much heavier and are not much fun to lug around. Typically guys just get longer hoses for them so they need not move them frequently. Oiled compressors have a much higher starting amp draw and many can blow weak or undersized breakers on start up. On cold days that is even more of an issue(assuming the compressor isn't kept in a warm place)

Oil free compressors do not use oil. They are light weight and convenient to move around with one hand so you can get away with shorter hoses. They are not meant to run continuously. If you run them for long periods of time they will overheat and warp. They tend to run lower amperage's and cold weather has little impact on performance.

Most carpenters own a oiled compressor and a oil free compressor. The oiled is used for job-site construction for running framing guns and what not. The oil free is used for finish and punch work.

The average home owner can do everything just fine with an oil free unit. Even running a framing gun works out because Joe homeowner lacks the competence to run a framing gun and the same rate as a pro, so even if you are beyond the CFM of the compressor with the framing gun the compressor has plenty of time to recover in between shots.
#9
Old 09-14-2010, 10:03 AM
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Thanks! Looks like it's pancake time for me. The twinstacks are typically a good deal heavier, and heavier makes it less likely I will pull the thing out.
#10
Old 09-15-2010, 11:40 AM
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But Wait! What about the future?

I've got a big vertical 30 gallon job in the basement, and run pvc to a hose reel in my basement and to another one out by my driveway. PVC and hoses are cheap enough, (the hose reels aren't) and the bigger compressor will run more and multiple tools at a time. My compressor is still on wheels, and the rubber hose just connects to a fixed point in the basement. If I want mobility, I can still grab it and go, or leave it and just tie in to either of the (50') hose reels.
Forget the reels; you could just run some PVC to a fixed quick-connect point anywhere around the house; maybe one in the front, one in the back? It's like a water spigot. There's a couple around the house, and you just hook up a hose!

Think bigger and beyond just your immediate brad nailer needs. 175 PSI is great for cleaning the deck, driveway, basement, etc...

And when we have 14 kids over, all wanting their pool toys and floats inflated? Seconds, baby!

Won't someone think of the children?
#11
Old 09-15-2010, 12:11 PM
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for transfer of compressed air, materials and methods should be rated for that use. it is a major safety issue.
#12
Old 09-15-2010, 01:12 PM
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I work for an air compressor manufacturer, and actually sell the things -- both portable (pancakes and twinstacks) and stationary up to 120 gallon tanks. boytyperanma is exactly right. Think about what you're going to use the compressor for, and buy the compressor that will give you the appropriate CFM for the job(s).

For instance, if you want light duty (air brushing or craft nailing), you can get away with a small 1-4 gallon compressor of either configuration (pancake or twinstack).

You say you want light weight--I sell an oil-less twin stack that weighs about 30 lbs, which isn't bad. It's not like you're going to strap it to your back and carry it all day. The problem with that unit is it's light duty -- it's a great compressor, very reliable, just not designed for flooring nailers, so I wouldn't recommend something like that.

My company sells a flooring nailer that requires ~4 CFM, so as I said at the beginning, you need to look for a compressor that puts out at least that amount. If you get a lighter compressor, regardless of the configuration, it'll cycle on and off too often, and you'll be waiting forever for the tank to fill up, and I'd bet you'd end up getting frustrated and not use it. That's not Good Eats (apologies to Alton).

Summary: think about the jobs you want to accomplish, and the air tools you'll use, then buy the compressor that puts out at least the amount of CFM the largest tool requires. You'll run the tool efficiently, enabling you to finish your job faster; it'll cause less needless wear on the compressor, allowing it to last longer; and in the end, you'll be happier, because your compressor (which ain't cheap, even if it's a small pancake) will last for years.

Also, johnpost is correct. Use air transfer materials that are rated for air transfer. PVC is not recommended for use with air compressors. It's simply not rated for pressure that high (it could explode and cause a lot of injury from flying shards). It may be possible to find PVC that is, but it would be specifically rated for air transfer, and if it is out there, I've never heard of it. Copper, galvanized, or black pipe is preferred. Also, if you're setting up a shop, and not just using a portable compressor and hose (actually, even if you are), you should consider a filter and lubricator. These can help extend the life of your tools and compressor.
#13
Old 09-15-2010, 10:00 PM
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Quote:
Originally Posted by TriPolar View Post
Also, did the pancake fail on you? I'm leary of the oil-less concept, but I just put a little Mystery oil in everything anyway, and haven't had a problem. But nothing has had heavy use for a several years either.
Prelude provided excellent information. In the case of my oiless unit, it started to make some noise and I felt it was going to fail sooner or later. Everything does I guess.

I gave it to my BIL who will use it for occasional airbrush work. He knows it may need to be replaced soon.

Prelude is correct about the starting load. My Hitachi occasionally pops the breaker in the Winter.

Last edited by GaryM; 09-15-2010 at 10:01 PM.
#14
Old 09-16-2010, 12:22 PM
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I use my pancake compressor a lot simply due to its portability. I sometimes will even hook up my framing gun to it bang together a small wall. When I only have a few shots to do and it is close by, why not? Usually I just use it for small jobs with the brad nailer. If there is a lot of trim to shoot on I will go with the bigger compressor.

I think even the typical twin tank ~ 5 gallon compressors are working pretty hard with heavier guns. For framing or multiple guns a good, wheeled, belt drive compressor is the way to go. Much less racket, and can truly run continuously.

It is worth getting a proper brand name compressor Dewalt, Porter-Cable, etc. They are not much more expensive, more reliable, and if they come with a gun it wont be garbage.
#15
Old 09-16-2010, 01:48 PM
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Bostich? Is that a "name brand" still? I know many of the "name" brands selling entry-level units now, like Porter-Cable, Campbell Hausfield....is Bostitch a good unit?

Also, to everyone saying PVC is not rated for air....most of the compressors I am looking at come with a recoil-style PVC hose...so if that thin-walled PVC can handle the pressure, why is there fear that sch 40 would not? I am not trying to be combative, just looking for the reasoning behind this idea.

Last edited by crazyjoe; 09-16-2010 at 01:49 PM.
#16
Old 09-16-2010, 09:42 PM
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Originally Posted by crazyjoe View Post
Bostich? Is that a "name brand" still? I know many of the "name" brands selling entry-level units now, like Porter-Cable, Campbell Hausfield....is Bostitch a good unit?

Also, to everyone saying PVC is not rated for air....most of the compressors I am looking at come with a recoil-style PVC hose...so if that thin-walled PVC can handle the pressure, why is there fear that sch 40 would not? I am not trying to be combative, just looking for the reasoning behind this idea.
Bostich was bought out by Stanley tools, so the actual company name is Stanley Bostich, but yeah, they're still around (not the company I work for, by the by).
http://bostitch.com/default.asp?...&PAGE=HOME.HTM

For your question about PVC, you're right about the hoses -- there are PVC hoses rated for compressors, and what I meant when I said I wasn't aware of any PVC systems being being rated for air was more along the lines of the tubing, not hoses. To clarify what I mean, say you have a stationary compressor in your shop (garage, basement, or warehouse, etc.). You're going to connect rigid piping to it, and run that piping to regulators, filters, lubricators, etc. and finally to a valve, at which you connect your flexible PVC hose (similar in theory to running an electrical conduit from the breaker box to an outlet--the outlet is analogous to the air valve at the end, and the electrical conduit is analogous to the piping coming from the compressor).

Now, having said all that, and hoping like hell I'm making sense, it's the rigid piping (electrical conduit) that can't be PVC. The flexible hose you actually connect to your tool (the cord attached to your clothes iron, TV set, or any other electrical appliance) can be made of PVC (remember before I said it can't unless it's specifically rated for air use? That flexible hose is made for that task, so it's okay to use in that situation).

So....to answer your question about the reasoning behind it, the simplest way of answering that is engineers have discovered that PVC pipe isn't the best material to handle the high pressure coming out of the compressor (there are now 200 PSI compressors on the market, and it's not unusual for compressors to blast out 100, 125, 135, or even 175 PSI). Standard PVC pipe simply isn't meant for pressures that high. I'm sure they could make PVC pipe that can handle it, but why? It'd probably be prohibitively expensive, and probably heavier than necessary. Especially when other materials that are on the market work better (see my previous post).

Finally, take a look at the diagram here (PDF) Ignore the fact that the system's attached to a blast cabinet, that part's irrelevant. It's the tubing I really want to point out with this. It also gives good reasoning why you should use metal pipe. (I wish I'd found that diagram before I went all verbose on youse guys.)

Oh! One other thing -- always, always, always drain your compressor when you're finished using it. Air will condense inside the tank and eventually rust it out, making it useless (and dangerous to boot, if it gets weak and explodes). Doesn't matter if it's a 1-gallon tank or a 120-gallon. Drain the tank after every use. And oil your tools, unless they specifically don't need to be oiled. IOW, perform proper maintenance like you would with anything else you own.
#17
Old 09-16-2010, 09:52 PM
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Quote:
Originally Posted by GaryM View Post
Quote:
Originally Posted by TriPolar View Post
Also, did the pancake fail on you? I'm leary of the oil-less concept, but I just put a little Mystery oil in everything anyway, and haven't had a problem. But nothing has had heavy use for a several years either.
Prelude provided excellent information. In the case of my oiless unit, it started to make some noise and I felt it was going to fail sooner or later. Everything does I guess.

I gave it to my BIL who will use it for occasional airbrush work. He knows it may need to be replaced soon.

Prelude is correct about the starting load. My Hitachi occasionally pops the breaker in the Winter.
Naturally the compressor's going to wear out at some point, and oil-less will fail before oil-lubed models. They're just designed that way (lighter duty and all).

Popping the breaker sounds like you may simply have too much on that circuit. I'd check the amp rating of the compressor against the circuit, and see what else is on there. Dammit Jim, I'm a salesman, not an electrician! But I get calls sometimes from customers who complain about the same problem, and it can be a variety of things. Of course, it all boils down to too much amperage for the circuit, but you need to investigate where that's coming from. Other appliances on the same circuit causing an overload? A short somewhere?
#18
Old 09-16-2010, 10:08 PM
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It's a 15 A circuit. The electrician should ave made it a 20 A, but it's way too late to run new wire. If I plan on using a lot of air I plug into a 50A 110 circuit.
#19
Old 09-16-2010, 10:09 PM
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Quote:
Originally Posted by Prelude to Fascination View Post

Popping the breaker sounds like you may simply have too much on that circuit. I'd check the amp rating of the compressor against the circuit, and see what else is on there. Dammit Jim, I'm a salesman, not an electrician! But I get calls sometimes from customers who complain about the same problem, and it can be a variety of things. Of course, it all boils down to too much amperage for the circuit, but you need to investigate where that's coming from. Other appliances on the same circuit causing an overload? A short somewhere?
The compressor I have now used to throw the breaker in my old house all the time. Here in the new house, no problems. Some systems just can't deliver the load I guess. But sometimes, a particular breaker trips too fast. They're supposed to have a small lag time because of the surge when a heavy load is added. I forget the time factor, some fraction of second IIRC. Sometimes a particular breaker is too sensitive and changing it may help. I'd guess that would typically happen when the load on a breaker is around the maximum anyway.
#20
Old 09-16-2010, 10:14 PM
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Hmmm.

In my basement, I've mounted Schedule 40 PVC "conduit" as my rigid piping to the hose reel in the basement, and almost 100' away to the outdoor hose reel.

Looking here for example, my PVC setup far exceeds the 150psi max I can put in to it. I'm putting in less than 1/2 the MOP.

It's been there for at least 10 years with no sign of trouble.

Do I really need to replace it? Why?
#21
Old 09-16-2010, 11:42 PM
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Originally Posted by ducati View Post
It's been there for at least 10 years with no sign of trouble.

Do I really need to replace it? Why?
The SCH 40 I've seen has always explicitly said not to use with compressed air.

Here is the issue - Plastics like polycarbonate flow or melt when stressed. PVC cracks and breaks into pieces when stressed. That means when the 10 year old piping you have gets hit by an errant ski pole, or other object, it's not just going start leaking air, it may literally explode, posing a risk of injury.

Air compresses a lot and when the pipe starts to yield, the air pressure doesn't drop as soon as some air starts to leak. So as the initial crack propagates down the pipe at great speed, and the air pressure maintains, you end up with a bang that has lots of high speed plastic flying around your basement.

Water on the other hand doesn't compress much compared to air so if the pipe starts to yield (at the same pressure as it would with air) and water starts leaking, the pressure drops very rapidly at the source of the leak. This pressure drop at the crack means the cracking progresses much slower and there is very little high speed plastic (none really).

It's the same reason that a balloon filled with air goes BANG when popped, and one filled with water just gets you wet when popped. Now amplify that effect by a 100 to get a feel for the difference bewteen 150PSI of air, and 150PSI of water.
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