# air line runs in shop

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• posted on February 2, 2008, 6:42 pm
Received great comments on haning the air filter unit..now on to the next question - compressor lines
Have small (8 gallon, 120 PSI rated) compressor, would like to run an airline up the wall, and overhead to the center of my garage, connection to a reel mounted on the ceiling (11'). Total length of run from compressor to the reel is around 30' or so. The reel itslef has 25' of hose, so total run end to end, at most, would be 50'-60'.
Know the compressor is small, so is my budget, does it have enough "oomph" to produce/maintain pressure at max run - 60 feet?
And no, can't just go buy a bigger unit :)
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• posted on February 2, 2008, 7:37 pm
wrote:

compressor for is to blow off dust then you will have no issues. Pressure and volume make tools work. A dust nozzle requires some pressure and some volume. Painting a car with a spray gun might require a lot of volume and modest pressure like 50 psi. Running a dual action sander might require a lot of volume. Maybe 5 cfm at 90+ psi. Some cheap tools require a lot of air and sometimes expensive tools require less air.
Every fitting and every turn reduces the volume and pressure a little bit. Undersized pipe causes problems.
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<%-name%>
• posted on February 2, 2008, 8:34 pm
The answer to your question depends on lots of things: -Pumping rate of compressor at 120 psi -ID of hose -ID of the line you will run to it. -How much air flow you need at the end of the hose. -Pressure you need at the end of the hose. ----and probably a half dozen other things I forgot.
The pumping rate is key. You could have a 120 psi compressor that supplies 1 cu ft per minute or it could supply 10 cfm. I think you'd want at least 4 to 6 cfm at 120 psi.
Okay, so the compressor is "rated at 120 psi". What are the on and off pressures set at? If I was thinking "120 psi" I'd want a system that turned on at 120 psi and off at something higher, like 140 psi, so I'd actually HAVE 120 to use. If that is true, and if the highest pressure you need is, let's say 90 psi, you have some "room" for a pressure drop along the system.
If you need more volume at pressure than your compressor can supply, although you said you can't afford a bigger compressor, you might get bigger receiving tank. If you do this, make sure it's rated for the pressure you intend to use. This way you'd get a longer duty cycle between "waits" for the compressor to catch up. ----Again, depends a LOT on what you want to do.
You need to identify the tools that you want to use.
With 3/8" hose and 1/2" lines to the reel, you'll have no problems with impact tools, but it might be touch and go with a high powered grinder running in more or less continuous mode.
Pete Stanaitis ------------------ cc wrote:

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<%-name%>
• posted on February 2, 2008, 9:54 pm

The HP of the compressor has nothing to do with having enough "oomph" to move air that far. 1/2 HP or 30 HP it just depends on how much air you want at the other end of the line, then size the line diameter accordingly. In your case 1/2" plumbing copper will do, 1/2" black pipe too. On the cheap, a 1/2 air hose from Harbor Freight would probably do fine too.
DO NOT USE PVC PIPE MADE FOR WATER LINES!!!
Greg
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• posted on February 2, 2008, 10:03 pm

The length of the hose could be 1000 feet and would not affect pressure. Volume/flow could be affected however. As long as you are only using the air to blow dust, fill tires or operate nail guns you should be able to run just about any length that you want.
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• posted on February 3, 2008, 2:42 am

I did the research and ran the calculations just a couple of weeks ago because I ran an air line about 100 feet from my shop to the center of my garage ceiling. Pressure is the same everywhere in the system until the air starts flowing. Then the friction of the air moving along the sides of the pipe reduces the pressure a little for each inch it travels. The pressure drop from all those inches adds up and the total pressure drop depends on flow rate and pipe size and pipe length. If you'll use 1/2" pipe on a run of less than 100 feet, the pressure drop is negligible at the flow rates your compressor can maintain. In other words you'll get the same performance at the end of the line that you would get if you hooked directly to the compressor. In fact, 100 feet of 1/2" pipe will add about 1 gallon of capacity to your tank - not that you'll notice. PVC pipe is out because it shatters when it fails, but you can use polypropylene or polyethylene water pipe. It's usually black, and comes in a roll.
DonkeyHody "Every man is my superior in that I can learn from him." - Thomas Carlyle
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• posted on February 3, 2008, 3:27 am
wrote:

I don't think you'll have any problem at 60" or so.
Mike O.
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<%-name%>
• posted on February 3, 2008, 3:29 am
"Mike O." wrote

Five feet...or so?
Max
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• posted on February 3, 2008, 6:03 am

OP
forgot to mention that the compressor only has a 1/4" nip, so does that mean having a 1/2" main run buys me anything, given I will have to have a reducer at the compressor itself, or does it matter?
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• posted on February 3, 2008, 6:20 am
RE: Subject
Run 3/4 black iron pipe for the hard piping.
Relatively low cost, provides some added storage capacity to minimixe pressure drop from pulse devices such as nail guns.
Will be totally meaningless for a spray gun.
Lew
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• posted on February 3, 2008, 6:53 am

3/4" is way overkill for a home shop with less than 100 foot run. 1/2" pipe will flow any hand tool most of us have laying around. Do some research online and see what the CFM ratings are at different lengths. The last chart I saw gave 1/2" pipe, at 100 feet of length, 54 CFM at 100 PSI, probably good enough! Years back in a shop I had I ran 1/2" black pipe. I put a pressure gauge at the end of the run, where the most work was. No tool I owned at the time would even make the gauge pointer wiggle when the tool was run. Greg
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• posted on February 3, 2008, 7:36 am
"Greg O" wrote:

Lew
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• posted on February 3, 2008, 7:58 am

What does "floating my boat" have to do with realistic air line sizing?? I was jut stating the fact that 3/4" is over kill, which it is. The OP is looking for a budget way to run air lines in his shop, why go 3/4" when 1/2" is oversized to begin with? I guess if 3/4" is better, than 2" is way better yet? Where does it stop? Greg
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• posted on February 3, 2008, 1:35 pm

Realistic depends on use. We have 6" in our shop. Three large tanks too.
The larger line also acts as a reservoir of air so there are advantages under some circumstances. Doesn't make a difference for a couple of taps on a brad nailer, it will with an air wrench.
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<%-name%>
• posted on February 3, 2008, 2:39 pm

Well actually, 2" pope would give you a larger air storage capacity. ;~)
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<%-name%>
• posted on February 3, 2008, 2:41 pm
On Sun, 03 Feb 2008 14:39:18 GMT, "Leon"

And a blessing!
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<%-name%>
• posted on February 3, 2008, 6:16 pm
"Greg O" wrote:

The cost differential between 1/2 & 3/4 pipe gets lost in the wash when looking at the total installed cost.
Cutting and threading costs whether done with the installers own tools or purchased from the pipe supplier, will be the same for either 1/2 or 3/4.
Installation labor will be the same either 1/2 or 3/4, even it is only sweat equity.
After all, sweat equity is a supply limited item, thus has a cost other than just economic.
Thus, "....whatever floats your boat" applies, IMHO.
BTW if this werte a serious pneumatic system, 2" pipe would be the pipe of choice for a home shop system.
Why 2"?
Why not larger?
Ever try to thread fittings on anything larger than 2"?
Why not smaller?
Poor economics.
Enuf said.
Lew
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<%-name%>
• posted on February 3, 2008, 6:30 pm

Yabbut, using 6" piping will be like having another reservoir <G>
Max
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• posted on February 3, 2008, 6:43 pm
Max wrote:

If you use 6", I would go with butt weld. 6" screw pipe requires two 72" pipe wrenches and is a real pain to run. VERY hard to get started, especially with long runs (over 20'). I have run alot of this and it is NOT easy.
--
Robert Allison
Rimshot, Inc.
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• posted on February 3, 2008, 7:24 pm
"Robert Allison" wrote

Thanks for the tip. Glad I have a welder. <BG>
Max