# air compressors - how big for certain tasks?
**URL:** https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779
**Category:** Factual Questions
**Created:** [January 17, 2012, 7:41am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779 "2012-01-17T07:41:01Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@crypto](https://boards.straightdope.com/u/crypto)
#### Post date: [January 17, 2012, 7:41am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/1 "2012-01-17T07:41:01Z")
I have seen air compressors of all different shapes and sizes, all offering different air pressure outputs.
What size air compressor would I need if I wanted to use some air power tools, like a power drill?
Is there a general rule of thumb on these things, or does each product indicate a reference pressure?
If I had a number of different tools, like a drill and a paint spray gun, I’d assume they would use different pressure requirements. Would one compressor be able to handle everything as long as it managed the top level requirement?
Thanks
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### Author:  [@Ostrya](https://boards.straightdope.com/u/Ostrya)
#### Post date: [January 17, 2012, 9:25am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/2 "2012-01-17T09:25:35Z")
Am not knowledgeable about compressors, but want to say I like this [Makita](http://www.amazon.com/Makita-MAC700-Big-Bore-Compressor/dp/B0001Q2VK0) “hotdog” type, have a similar model to this one for 20 yrs now and it works just fine for air wrenches, power tools, filling car tires.
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### Author:  [@Khendrask](https://boards.straightdope.com/u/Khendrask)
#### Post date: [January 17, 2012, 9:53am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/3 "2012-01-17T09:53:27Z")
Compressors are generally rated with working pressure, and cubic feet per minute supply at a given pressure. For just about any hand tool used for construction, almost any decent quality ‘Pancake’ tank compressor will be fine, in the 3 to 6 gallon tank size. Higher volume applications like spray painting do well with a compressor that has a high SCFM rating, but those will be larger compressors, and have bigger motors and tanks. For anything but the smallest scale sand, ice, or bead blasting, you need a compressor with a huge SCFM rating, as those are 100% duty cycle applications.
Although not listed usually in the ‘big box’ store catalogs, every air tool sold has somewhere listed a design working pressure, and an SCFM requirement. As long as your compressor can supply the tools SCFM at it’s working pressure, you can use the tool continuously without any interruption. If the tool requires more SCFM then the compressor can supply, then you will still be able to use it, but will have to let the compressor tank charge up after a certain number of cycles (or, leave a longer delay between tool operation cycles).
Yes, one compressor can handle all your tools, if it is rated for the highest tool you want to use (or the sum SCFM of all tools you want to use at the same time). Even if it is slightly under-capacity, you can still use most air tools, at a reduced duty cycle (spray painting included except for large volume applications).
I’d think you would do fine with something in the 3 to 5 SCFM @ 90 PSI rating, lower if it has a rapid recovery pump, and a 4 to 6 gallon tank. That covers almost anything needed for most single tool at a time work.
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### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [January 17, 2012, 2:35pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/4 "2012-01-17T14:35:09Z")
Advice from a long time compressor user: do NOT buy an oiless compressor unless it’s all you can afford!
They are noisier and wear out faster than the ones with oil lubrication. Yes, the oil free units are a little lighter, but unless you’re lugging it up and down ladders all day it no big deal.
You can use a slightly under sized unit for bigger jobs if you’re will to take short breaks while it catches up with your demand.
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### Author:  [@johnpost](https://boards.straightdope.com/u/johnpost)
#### Post date: [January 17, 2012, 3:01pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/5 "2012-01-17T15:01:34Z")
a new compressor might be marketed indication the tasks it is good for. a store or catalog might provide a chart with uses possible for the different compressors offered.
a 15 gal., 6.0 CFM, 90 PSI compressor might be marketed indicating that it is not good for sand blasting, sanders or automotive paint spraying (seems profession, home paint spraying is OK). it is maybe OK on drills, grinders and cutoff tools (meaning you might have to recharge if running the tool for long times).
a compressor might have a regulator to change output pressure. you can also buy regulators, oilers, filters to put in line after the compressor depending on what you are using it for.
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### Author:  [@Kevbo](https://boards.straightdope.com/u/Kevbo)
#### Post date: [January 17, 2012, 5:16pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/6 "2012-01-17T17:16:00Z")
Also be aware that there is widespread lying with regard to HP ratings of consumer grade compressors. You can expect to get about 1.5 shaft HP out of a 115V, 15A outlet. Significantly more than that is pure fiction.
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### Author:  [@beowulff](https://boards.straightdope.com/u/beowulff)
#### Post date: [January 17, 2012, 5:23pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/7 "2012-01-17T17:23:14Z")
All air tools are rated at CFM air consumption @ X psi pressure.
You need to pick a compressor that can meet your maximum air consumption at the duty cycle you desire. Note that there are some tools which are real air hogs - orbital sanders are one of them.
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### Author:  [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)
#### Post date: [January 17, 2012, 8:52pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/8 "2012-01-17T20:52:26Z")
> [@Khendrask](#):
>
> For anything but the smallest scale sand, ice, or bead blasting, you need a compressor with a huge SCFM rating, as those are 100% duty cycle applications.
I’ve been sandblasting for several years using [url=[TP Tools & Equipment](http://www.tptools.com/p/1024,22_Foot-Pedal-Operated-Power-Gun.html)]this C-25 gun. My compressor was rated for 11 CFM at 90 psi, but it gives marginal performance with this gun. I’m in the middle of upgrading, retrofitting my tank with an 18-CFM pump and a 6.5-hp electric motor. That ought to be a lot better.
And yes, don’t try sandblasting with an oil-free compressor; they aren’t made for continuous duty.
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### Author:  [@Projammer](https://boards.straightdope.com/u/Projammer)
#### Post date: [January 17, 2012, 10:58pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/9 "2012-01-17T22:58:46Z")
> [@beowulff](#):
>
> All air tools are rated at CFM air consumption @ X psi pressure.
> You need to pick a compressor that can meet your maximum air consumption at the duty cycle you desire. Note that there are some tools which are real air hogs - orbital sanders are one of them.
This is the short answer to your question. Finding out the CFM requirements of your most demanding tool and then getting a compressor that can comfortably handle that.
[Here is a table](http://www.engineeringtoolbox.com/air-consumption-tools-d_847.html) of the typical comsumption rates of most common air tools.
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### Author:  [@crypto](https://boards.straightdope.com/u/crypto)
#### Post date: [January 18, 2012, 2:24am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/10 "2012-01-18T02:24:03Z")
thanks for the replies everyone.
I’m interested in handling all of the basic tools, like a screwdriver, drill, etc.
But the one thing I’m very interested in using it to sandblast. Not a car, but some smaller parts to prepare for restoration painting.
sounds like I should seek an oil lubed compressor. I’ll look at Projammer’s list to see what I can get away with. It’s amazing how expensive these can be, so I want to make sure I get one that will be useful no matter what task I’ll be using it for. The only thing I could possibly see using this down the road is to spray paint a car. I don’t have anything scheduled, but I may decide to tackle a paint job on one of my restoration projects.
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### Author:  [@beowulff](https://boards.straightdope.com/u/beowulff)
#### Post date: [January 18, 2012, 4:39am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/11 "2012-01-18T04:39:28Z")
> [@Stink Fish Pot](#):
>
> thanks for the replies everyone.
>
> I’m interested in handling all of the basic tools, like a screwdriver, drill, etc.
>
> But the one thing I’m very interested in using it to sandblast. Not a car, but some smaller parts to prepare for restoration painting.
>
> sounds like I should seek an oil lubed compressor. I’ll look at Projammer’s list to see what I can get away with. It’s amazing how expensive these can be, so I want to make sure I get one that will be useful no matter what task I’ll be using it for. The only thing I could possibly see using this down the road is to spray paint a car. I don’t have anything scheduled, but I may decide to tackle a paint job on one of my restoration projects.
I suspect that a typical “handyman” 20 gal compressor would be fine.
Something like [this](http://www.homedepot.com/buy/tools-hardware/air-compressors-tools-accessories/husky/20-gallon-vertical-portable-compressor-92120.html).
I have a 30 year old compressor similar to this, and it does everything I need. I have a sandblast cabinet, and I sandblast and etch small parts with no problems.
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### Author:  [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)
#### Post date: [January 18, 2012, 5:46am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/12 "2012-01-18T05:46:27Z")
There also seems to be a fair bit of lying when it comes to actual SCFM claims. I would stick to major brands if it is going to get a lot of use.
I am not convinced about the oil vs oil free compressor thing. I have had a couple twin stack oiled compressors that really were not any quieter, capable, or durable than similar sized oil free units. They may last longer but bigger name oil free units can be given new rings relatively cheaply and easily. I think oil free is a great choice for light duty work. If you really need something heavier duty you should be gong to a belt drive unit anyway.
I use my porter cable pancake compressor the most, it is light and portable and has good recovery. It is great for finishing work and can even run a framing gun reliably. If I need to use a stapler or anything air hungry I am going to be using something a lot bigger (and much more expensive)
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### Author:  [@johnpost](https://boards.straightdope.com/u/johnpost)
#### Post date: [January 18, 2012, 3:05pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/13 "2012-01-18T15:05:46Z")
a 6 or 10 gallon unit is portable in regard to taking up long stairways or outdoors. it might not do much sandblasting, sanding or grinding without recharge periods.
a 20 gallon unit is portable on a smooth hard surface. it will sandblast and grind.
you also get some of the effect of portability with multiple hoses run out a doorway or window.
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### Author:  [@crypto](https://boards.straightdope.com/u/crypto)
#### Post date: [January 27, 2012, 6:25am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/14 "2012-01-27T06:25:52Z")
After some research, it looks like I’ll be shooting for a 20 gal compressor.
my desire to sandblast is the driving factor, and it will most likely meet those needs.
Now, the big question… what brand should I look for? I don’t want to base this all on price, but I don’t want to get screwed either.
The big box stores concern me, because many product manufacturers dont use the best materials or manufacturing techniques to make the price as low as possible. I saw the “Husky” brand posted by beowulff, and it looks fine, but I don’t know anything about the brand.
Also, I’ve seen many of these used compressors on craigslist. Are these things a bad idea to buy used? how quickly do they go bad?
I don’t want to buy a used one from cl, thinking I’ve saved some money when it is not producing the power I need.
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### Author:  [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)
#### Post date: [January 27, 2012, 3:33pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/15 "2012-01-27T15:33:06Z")
> [@Stink Fish Pot](#):
>
> After some research, it looks like I’ll be shooting for a 20 gal compressor.
>
> my desire to sandblast is the driving factor, and it will most likely meet those needs.
Your primary spec of concern is CFM, not tank capacity. Although they tend to scale together, there is quite a bit of variation.
How big are the objects you’ll be sandblasting? Jewelry, or dinner plates? If the former, you can probably get away with a compressor rated for 5-8 CFM, and you’ll want to buy an appropriately small sandblasting gun, like [the small one on this page](http://www.tptools.com/p/1024,22_Foot-Pedal-Operated-Power-Gun.html); if the latter, you’ll want 12-15 CFM, and choose something like the medium gun at that link.
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### Author:  [@crypto](https://boards.straightdope.com/u/crypto)
#### Post date: [January 28, 2012, 4:18am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/16 "2012-01-28T04:18:34Z")
> [@Machine\_Elf](#):
>
> Your primary spec of concern is CFM, not tank capacity. Although they tend to scale together, there is quite a bit of variation.
>
> How big are the objects you’ll be sandblasting? Jewelry, or dinner plates? If the former, you can probably get away with a compressor rated for 5-8 CFM, and you’ll want to buy an appropriately small sandblasting gun, like [the small one on this page](http://www.tptools.com/p/1024,22_Foot-Pedal-Operated-Power-Gun.html); if the latter, you’ll want 12-15 CFM, and choose something like the medium gun at that link.
I’ll be sandblasting old car parts. Things that need a repaint.
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### Author:  [@Jamicat](https://boards.straightdope.com/u/Jamicat)
#### Post date: [January 28, 2012, 9:56pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/17 "2012-01-28T21:56:27Z")
If your gonna sand blast better get a good dryer. 😉
[http://www.google.com/search?q=air+drier&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a#q=air+dryer&hl=en&client=firefox-a&hs=sfw&rls=org.mozilla:en-US:official&tbs=p\_ord:p&tbm=shop&sa=X&ei=624kT7e8I8autwfji624Dg&ved=0CNgBELsNKAE&bav=on.2,or.r\_gc.r\_pw.,cf.osb&fp=d23267ce07f75cfc&biw=1440&bih=751](http://www.google.com/search?q=air+drier&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a#q=air+dryer&hl=en&client=firefox-a&hs=sfw&rls=org.mozilla:en-US:official&tbs=p_ord:p&tbm=shop&sa=X&ei=624kT7e8I8autwfji624Dg&ved=0CNgBELsNKAE&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=d23267ce07f75cfc&biw=1440&bih=751)
I got one of these on sale for $99.
> **[Harbor Freight Tools – Quality Tools at Discount Prices Since 1977](https://www.harborfreight.com/air-tools/air-compressors/2-hp-8-gallon-125-psi-portable-air-compressor-67501.html)**
>
> Harbor Freight buys their top quality tools from the same factories that supply our competitors. We cut out the middleman and pass the savings to you!
(it might have been the 2 or 2.5 HP)
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### Author:  [@Prelude\_to\_Fascination](https://boards.straightdope.com/u/Prelude_to_Fascination)
#### Post date: [January 29, 2012, 12:51am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/18 "2012-01-29T00:51:08Z")
> [@Stink Fish Pot](#):
>
> After some research, it looks like I’ll be shooting for a 20 gal compressor.
>
> my desire to sandblast is the driving factor, and it will most likely meet those needs.
>
> Now, the big question… what brand should I look for? I don’t want to base this all on price, but I don’t want to get screwed either.
>
> The big box stores concern me, because many product manufacturers dont use the best materials or manufacturing techniques to make the price as low as possible. I saw the “Husky” brand posted by beowulff, and it looks fine, but I don’t know anything about the brand.
>
> Also, I’ve seen many of these used compressors on craigslist. Are these things a bad idea to buy used? how quickly do they go bad?
>
> I don’t want to buy a used one from cl, thinking I’ve saved some money when it is not producing the power I need.
I used to sell air compressors for a major manufacturer, and can tell you the “Husky” is actually the private label store brand for Home Depot, just as Kobalt is the store brand for Lowe’s. I know of at least three different manufacturers for Husky, and as a rule of thumb, stick with the largest oil-lubed compressor you can afford and/or think you’ll need.
While the oil-free models are all right, and will do the job, a large oil-lubed model is made to last, and can be rebuilt (I talked to many customers who had the same compressor for 30+ years). My best advice is make sure the compressor’s made in the USA, and not imported. With the company I worked for, the imports (across the board, not just Husky brand) were much lower quality (made in China). That’s not to say they were crap, at least not completely, but for the most part, you couldn’t rebuild them, and were essentially disposable.
Harbor Freight’s a good place to shop if you’re using a tool once, or don’t need it to last a long time. My company made sure the better products went to Lowe’s and Home Depot in particular, but also sold to WalMart (although they didn’t carry very large compressors), Sears (understandable if you’d rather not shop there), and places like Ace hardware, True Value, and even smaller hardware stores.
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### Author:  [@TriPolar](https://boards.straightdope.com/u/TriPolar)
#### Post date: [January 29, 2012, 5:05am UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/19 "2012-01-29T05:05:35Z")
> [@Prelude\_to\_Fascination](#):
>
> …and as a rule of thumb, stick with the largest oil-lubed compressor you can afford and/or think you’ll need.
Absolutely. With the exception of portable units, get the most compressor you can reasonably afford.
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### Author:  [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)
#### Post date: [January 29, 2012, 8:05pm UTC](https://boards.straightdope.com/t/air-compressors-how-big-for-certain-tasks/609779/20 "2012-01-29T20:05:11Z")
> [@Stink Fish Pot](#):
>
> I’ll be sandblasting old car parts. Things that need a repaint.
Then you probably want the mid-size gun and a 10-15 CFM compressor, otherwise sandblasting will go very slowly.
Once the air cools inside the compressor tank, you’ll get condensation. A lot of that will travel out of the outlet to your sandblaster. You’ll want to collect as much of the running water as you can in a gravity trap; the remaining airborne droplets can be captured by a coalescing filter [like this one.](http://www.tptools.com/Product.aspx?display_id=74)
However, the air leaving that coalescing filter will still be at something close to 100% relative humidity. When it squirts out of the sandlbasting gun, the pressure drop will cause cooling, and you’ll end up with condensation. That’s not good. So downstream of the coalescing filter, you’ll want a desiccator, like [McMaster part #5163K21.](http://www.mcmaster.com/#air-compressor-dryers/=g0q0y9) I have both of these items (filter and desiccator), and they work great. The desiccant beads, once saturated, can be dried in a 350-degree electric oven (not a gas oven; too humid) and reused indefinitely.
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