J

Juicegoose

Well Known Member
Alternatives in pipe for shop air distribution.

Alright so I've been on a compressor/air line kick. Basically i'm trying to get everything setup so when I get into my new garage I can install all the wiring/air lines needed for the build. Along the same lines has been alot of research especially into the use of different types of piping possible for use in a shop air system. Here are the choices I've found. As a side note I recently came across the rapidair system www.rapidairproducts.com they seem to have a pretty cool little idea going. I've been researching their website. DISCLAIMER: I am in no way associated with the company stated just a builder looking to spread the knowledge that he's spent hours researching. Let me know what you guys use So that the other guys can have a better idea of whats being used.
1. Standard ole compressor hose-
PLUS
- Inexpensive
- Portable
- Can handle air pressure needed for our uses (150-175psi max.. and thats pushing it!)
MINUS
- tripping hazard
- material used on some styles can breakdown over time and not be good with contaminates.
2. Black pipe -
PLUS
- Can handle any air pressure you through at it
- very strong and durable exterior
- fittings and pipe easily available
- Better heat transfer then PVC or hoses
MINUS
- Very labor intensive to install
- Water will rust out pipe from inside(eventually)
- scaling can occur over time(scaling in black pipe is the tendency of the coating to start to flake off)
- specialized tools required for install(pipe threader, monkey wrenches)
- Heat transfer can induce pipe sweating which in turn can cause slight water damage depending on climate.
3. Copper piping -
PLUS
- Can handle any air pressure you through at it
- Won't rust or corrode
- Fitting and pipe easily available (Note: insure proper thickness is bought)
- better heat transfer then PVC or tubing
MINUS
- Labor intensive to install
- Not has durable as blackpipe
- Specialized tools required for install (pipe bender, cutter, solder, torch, knowledge of how to solder copper pipe)
- Heat transfer can induce pipe sweating which in turn can cause slight water damage depending on climate.
4. PVC -
- Inexpensive
- Fittings and pipe easily available
- Won't rust or corrode
- easily repaired or modified
MINUS
- Not rated or advised for compressed air
- degrades over time
- pipe easily cracked or broken
5. RapidAir flexible air lines
- Inexpensive
- easy to install
- easily adapted to larger pipe(blackpipe or there version of pipe airnet)
- easily removable
- No special tools required
MINUS
- Fittings seem to be bulky
- Availablity not as easy as others
- Max usuable pressure they recommend 150psi
- flexible pipe can be seen as not as a neat and tiddy install
 
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The Airframe shop that we did the finish build on our plane at uses PVC and never has had a problem. Cheap and should not have any problems with the pressure.
 
IMO opinion plain old air hoses from Harbor Freight, 25 and 50 foot lengths, cheap ($10) and portable. I've had them in my shop 10 years and not a problem or failure. Quick disconnects on the ends (same aviation department) and you are in business. Add "t"''s between sections and you are really set up.

PVC --- No Way in my opinion. If fractured it will explode and send pieces flying like a bomb.

Larry
 
This post is really just to give a little bit of info for people trying to figure out the options. The pro's and con's I have given were simply recuring +'s or -'s that have come up time and time again.
 
Shop Air

I have PVC in my new shop, but I did hide it behind the wall, except where the quick connects stick out.
I have read about the supposed dangers of PVC exploding, but I have known many people who used it for this over about 20 years or so and have never heard of anyone having a problem.
I considered using copper, but the cost comparison changed my mind.
 
Water

One thing I didn't seen mentioned is water removal. A compressor will put a lot of moisture-saturated air in the lines.

Unless you go with relatively expensive equipment like a refrigerant chiller or a high-capacity dessicant system, the basic way to handle water is to use long pipe runs with multiple drops, in an effort to cool the air and condense the water into liquid so a mechanical filter/trap can catch it.

To that end, I think better heat transfer should be listed as a big plus for copper and "black iron", compared to PVC or hoses.
 
I edited the post for Jhines comments which were valid but additionally added that along with the pluses of good heat transfer comes the possibility of sweating of the pipes.
Any sytem should be properly setup to deal with water and unless your installing a refridgerated cooling system or a fancy air dryer your options are the limited to the following
1. Buy a 2 stage air compressor. This will help the air to cool from compression process.

2. Upon leaving the compressor, run your main line vertical as soon as possible. The vertical rise will allow water to fall back down the pipe/tubing to a drain valve.

3. Where taps will extend from main line(where possible) they should be in the vertical position and a tee fitting at the bottom should be used instead of a 90 degree elbow. This is for the installation of a drain valve for the vertical run allowing removal of water.

4. angle all horizontal runs slightly down and away from compressor. This will allow any water in the lines to flow to the closest vertical and drop to one of those drains I told you to install in the 3rd tip!!!

5. Install a master regulator and tee fitting at the tank prior to going vertical with your main line. Alot of folks will install a master system pressure regulator right at the tank(unless the tank has an adjustable pressure regulator). Think of it as an overall system check. Even though your compressor might be capable of producing say 150-175 psi. For the purpose of building or anything else for that matter 100 PSI is all thats needed for the tools to operate. Set that master pressure regulator to 100 psi and that will cover all the tools. Then if you really want to go all out put a tiny regulator at the tool or at the line tap on the wall. I've always liked to pipe in a tee valve before my master regulator(unless the tank has quick connects already installed). I'll install a quick connect at this tee for use with a 50 foot air hose for blowing stuff off that need all 175 psi. Just a thought!

6. Install an automatic drain valve on your tank. These are available at your local aircraft building supply store ( harbor freight) for 10 bucks or so and will eliminate something else to remember to do before shutting down for the night.

7. Going extreme here but air condition your garage. This will help with the humidity in the shop and vastly drop the water saturation that can contribute to water in your lines. Remember DRY AIR IS HAPPY AIR!!!

8. Install water seperators at the drop lines before your quick connects. By the time the water and air have gotten to this point in the system. If you've designed the system well alot of the water will have already dropped out of the air and be making it's way to a drain. The air thats left or that has been picked up with the flowing pressurized air will not be in vapor form and will then be seperated out by the seperator. Thanks to Jhines and others for pointing this out.


In general even though you are running air lines water needs to be addressed(especially in something like "black pipe" were rust can become an issue. Think of the whole experience like a big game of pipedream. You want to be able to allow that water to flow out of the system somehow all while keeping it flowing with the flow of air. Alll the above tips are just tools to help you get to level 43!!! (Ya i've been there)
 
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sf3543 said:
I have read about the supposed dangers of PVC exploding, but I have known many people who used it for this over about 20 years or so and have never heard of anyone having a problem.
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I worked in a shop that had a PVC air pipe failure... or shall I say explosion. Shards of PVC were thown all over the hangar, some of it very sharp. Thank God nobody was injured, but after seeing the results of the failure there is no way I would use PVC.
 
RV7Factory said:
I worked in a shop that had a PVC air pipe failure... or shall I say explosion. Shards of PVC were thown all over the hangar, some of it very sharp. Thank God nobody was injured, but after seeing the results of the failure there is no way I would use PVC.
Click to expand...

I have seen it as well. No way! It is a bomb just waiting to go off! :eek:
 
Flexible hoses must be well supported to avoid having low spots that will fill will water.

I found copper to be easy to install and it wasn't all that expensive. System works well, I get most of the water out of the valve at the first vertical, very little farther down the line.

Maybe I am wrong, but I thought a water separator close to the tank wouldn't be as effective as one farther down the line. Coming out of the tank, water is in vapor form and will pass on thru the separator with the air, farther thru copper lines it has condensed and will drop out in the separator. Am I wrong on this? My separator is at the end of the line, where I tap into it for shop air. I get very little water out of it, but my lines are so long that almost all the water comes out in my first 2 drains and very little from the last drain before the separator.
 
PVC A NO-NO

I am a plumbing and mechanical contractor and have customers ask all the time if we can run air lines in PVC and the answer is always no. Two main reasons, if the line is under pressure and gets hit you get a explosion, two when you have compressed air which includes oxygen (hopefully) and PVC pipe you can get static electricity which also gives you a explosion. I know its cheep but don't do it, use type (M) copper or air line hose.
 
RScott said:
Flexible hoses must be well supported to avoid having low spots that will fill will water.

I found copper to be easy to install and it wasn't all that expensive. System works well, I get most of the water out of the valve at the first vertical, very little farther down the line.

Maybe I am wrong, but I thought a water separator close to the tank wouldn't be as effective as one farther down the line. Coming out of the tank, water is in vapor form and will pass on thru the separator with the air, farther thru copper lines it has condensed and will drop out in the separator. Am I wrong on this? My separator is at the end of the line, where I tap into it for shop air. I get very little water out of it, but my lines are so long that almost all the water comes out in my first 2 drains and very little from the last drain before the separator.
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I used copper too and that's exactly what I did. As far as I know the standard "water separator" is just a set of vortex vanes and a porous filter above a sediment cup. I don't believe it has any ability to remove water in the vapor state, so you have to condense the water out to do any good.
 
Ya'll are correct I'm just stating the systems i've seen installed. Not to say they are wrong but I agree that a seperator at the tool tap would be best. I'll adjust the post
 
re: black pipe

I too am a licensed plumber. I would never use PVC for air lines for the reasons stated above, explosions. I used 3/4" black steel threaded pipe for my air lines.
I ran them overhead and on the drops, I put a tee and a nipple at the bottom with a ball valve on it for a drip leg. I also used very few ells, I used tees with plugs in the ends in case I wanted to run air somewhere else. Just pull the plug and start screwing pipe together.

Marshall Alexander
 
Little side note but in the past i've heard alot of people say that copper was to expensive when compared with black iron.
a quick look at the big orange box store found this
3/4" x 10' black iron pipe - 16.79
3/4" x 10' copper "L" - 17.94
 
PEX

i didn't see this mentioned. it should fail by splitting rather than exploding.

Of course one needs to borrow a crimping tool (i was fourtunate to be able to do this).

But I now have PEX airlines and it was pretty economical..at about 25C a foot for the pipe plus each fitting was in the 1 to 2 dollar range.

Frank
 
air supply

the shop where I work has pvc lines but they are not thin wall. use the hot water pvc with a thick wall and it will handle normal air pressure. Use brass valves. One thing for sure I would never use is the coily coily wrap around hoses. Talk about tripping you flat on your face ohh yeah. The best hose Ive seen is the stiff but limber no kink kind that makes nice wide curls and straight runs when you lay it out but resists kinking. I found that at the gun or drill, the stiff hose is a bit of a problem and sometimes makes it hard to curl the hose around to get the angle you want for the drill or rivet gun. I havent tried it but a short run of more limber hose maybe 6 or 8 feet at the gun will be a real help..In any case have fun with those thousands of holes your gonna drill and rivet. :D
 
re: CPVC

The hot water type is CPVC, not PVC. Don't use it either. When it ages, and is subjected to temperature differences, it gets as brittle as glass. As I said before, you can't beat the threaded steel. If you're concerned about rust, use galvanized steel pipe. Bottom line is DON'T USE PLASTIC PIPE FOR AIR LINES. I don't care if it's schedule 40 or not, don't use it. I know, some people have used it for years and haven't had any problems. But, then again, some people scud run and haven't have any problems.............yet.
This thread kind of goes along with the one about shop lighting and receps. Just do it right the first time. Then you can sleep at night not worrying about it.

Marshall Alexander
 
RV10Man said it right. Just do it right the first time. It really boils down to budget. I personally wouldn't use PVC of any kind CPVC or the other types. Working in the electrical field for a couple of years every once in a while we would come across some old sch 80 that had been ran on the back on the house and let me tell ya that stuff was brittle. With the slight price increase of copper over black iron. it might be a good alternative. copper for sure would be easier to modify down the road if say you want to add another tap or modify a line.
 
frankh said:
i didn't see this mentioned. it should fail by splitting rather than exploding.

Of course one needs to borrow a crimping tool (i was fourtunate to be able to do this).

But I now have PEX airlines and it was pretty economical..at about 25C a foot for the pipe plus each fitting was in the 1 to 2 dollar range.

Frank
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PEX is a great idea. I use it for all of my plumbing remodels. Very cheap and easy to use. But most of us were able to build our planes with one simple compressor and one simple hose. Too much over thinking here!
 
pex

TSwezey said:
PEX is a great idea. I use it for all of my plumbing remodels. Very cheap and easy to use. But most of us were able to build our planes with one simple compressor and one simple hose. Too much over thinking here!
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Be careful about PEX too.
It is only rated for 80psi in 3/4" and 100psi on 1/2" IIRC.
Lots of small cabinet shops use pex around the shop walls, etc. But
the normal finish nailers and brad guns only use about 80psi or less.
So depending on what you have planned, the pex may not handle the pressure.

I used copper lines in my shop and it was pretty easy to install compared to
threaded pipe!! I agree with "do it right the first time"!!
 
I agree with the overthinking here. I've always just used the air line roll-up reel, and mounted it above the compressor on the wall, right next to the water separator and regulator/separator. That way the hose gets rolled up and out of the way very quickly when not in use. I replace the hoses every time I've finished an airplane right before I start painting, so I have nice new fresh hoses to paint with.

Vic
 
For those guys that have used copper to pipe shop air. What fittings did you use to go from copper to the quick disconnect needed to connect the air line?
 
Overthinking

Bob Martin said:
Be careful about PEX too.
It is only rated for 80psi in 3/4" and 100psi on 1/2" IIRC.
Lots of small cabinet shops use pex around the shop walls, etc. But
the normal finish nailers and brad guns only use about 80psi or less.
So depending on what you have planned, the pex may not handle the pressure.

I used copper lines in my shop and it was pretty easy to install compared to
threaded pipe!! I agree with "do it right the first time"!!
Click to expand...

Two things

1) If Pex is only rated to 100psi then it burst pressure is at least 200Psi..Its not going to fail. Besides I really can't ever see the need for more than say 125 psi..Good point though as some compressors can go to 150. Really never going to need anything bigger than 1/2 inch for the flowrates you could ever use in a simple shop.

2) For me I have already finished the airplane..Its long gone from the shop. This is more about not having to trip over an airline that is used to fill the numerous tires of sundry equipment..The lawn tractor is in a different room of the shop and has a slow leak etc..So I have to currently drag an airline though a couple of doors.

This way I have an airline drop in every room..I just finished it this morning in fact.

I'll turn the regulator down to 100 Psi thats more than adequate.

Frank
 
What psi is sch 40 rated for?

Check this link out I remember this from several years ago, http://www.engineeringtoolbox.com/thermoplastic-pipes-temperature-strength-d_794.html[/URL]
 
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Can't remember

But schedule 40 refers to either PVC, CPVC or ABS....All are notch sensitive and fail explosively.

Now another note on PEX..I was just at the local Home Depot and th Sharkbite brand is rated for 160 psi at 73F dropping down to 100psi at 180F..So even at 100F it should be good for a rated pressure of at least 125psi.

This was printed on both 1/2" and 3/4" sizes..but 3/4" is way overkill.

Good enough for a distribution system..I put in 80 feet with a number of tees and end fittings and it came to about $40 total, excluding the quick connect valves on the ends.

I'm happy..:)

Frank
 
vic syracuse said:
I agree with the overthinking here. I've always just used the air line roll-up reel, and mounted it above the compressor on the wall, right next to the water separator and regulator/separator. That way the hose gets rolled up and out of the way very quickly when not in use. I replace the hoses every time I've finished an airplane right before I start painting, so I have nice new fresh hoses to paint with.

Vic
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I am going to agree with Vic's agreement. :) I had originally planned to replace my hose reel with hard piping of some sort, but after using the hose for some years I've never really felt the need.

If you are going to use the standard air hoses, then my suggestion would be to buy one of the lightweight hose kits that Avery or Cleveland sells. You then use it to connect your tools to the big hose... this way the big/heavy hose can stay on the floor.

Sounds like Vic and I have similar set-ups. Pay NO attention to the bucket!
compressor.jpg
 
I assume

The bucket is a water condensor?...You can keep ice in the bucket..I did a similar thing for the painting

Frank
 
Maybe missing a key point here.....one method will not work for all.

Think about where you live, your typical atmospheric conditions, and where you've located your compressor intake. A builder in a dry climate or a builder pulling air from an air conditioned space may not need much more than a hose. Down here in south Alabama a compressor pulling outside air and running continuously in the summertime will result in huge quantities of water at the tool.

Take a look at the two charts on this page:

http://www.engineeringtoolbox.com/water-vapor-air-d_854.html

20%RH and 100F is 58 grains of water per pound of air (hot dry climate)
50%RH and 70F is 55 grains per pound (compressor intake in air conditioned shop)
90%RH and 90F is 195 grains per pound (outside compressor intake, Deep South coastal climate)

The best thing about good shop piping is the ability to remove water. A water separator removes liquid water, not water vapor. To remove water vapor you must first cool the air to condense the water to liquid. Best way to do it is to run the air through as many feet of metal pipe as you can arrange, preferably with the metal pipe in a cooled space. Install drops (water traps) at regular intervals.

Do you need this kind of setup just to run a rivet gun? No, not even in a wet climate. It's an intermittent low volume air demand. If the compressor isn't running constantly and has a big tank, most of the air cooling and water condensation is in the tank. If you live where it's hot/wet and your future shop dreams include high volume air demand (HVLP painting or something like a bead blast cabinet), install a decent metal pipe air system.
 
mattsmith said:
I am a plumbing and mechanical contractor and have customers ask all the time if we can run air lines in PVC and the answer is always no. Two main reasons, if the line is under pressure and gets hit you get a explosion, two when you have compressed air which includes oxygen (hopefully) and PVC pipe you can get static electricity which also gives you a explosion. I know its cheep but don't do it, use type (M) copper or air line hose.
Click to expand...

I can't imagine a situation where the O2 in compressed air could cause an explosion. Oxygen is not explosive. Pure oxygen does promote combustion of combustible materials and in the case of some chemicals, etc. will cause an explosion like reaction...

A, so far, not mentioned material for a distribution system is 3/8 or 1/2 " nylon tubing. Be aware that the pressure rating of nylon changes with temperature. The temp vs pressure rating is available on the data sheet.
 
Great post Dan, Here is my builders log website. http://websites.expercraft.com/markm1/ A click on the "workshop" tab will bring up some pics of the air set in my garage. I did a little research and found that copper was the easiest material to work with over black pipe as you just cut, clean and sweat on the lines. Living in a wet climate in Houston meant that dry air for priming and paint work would be tough to come by without a proper air dryer set up.

I come out of the compressor and immediately have a shutoff valve for safety. Then a flex line to a 175psi air dryer. I then run the copper line up the wall and over to the other side of the garage make a 90 degree turn and then run the length of the other wall with two drops. Both drops again have shutoff valves and dryers and one has an oiler for the air tools.

This setup is a little overkill for an RV project but I hope to move it to the hangar when the plane is complete. The Plumbing supply shop rated the copper lines at a burst pressure of 2100psi. Copper although slightly more expensive than steel pipe was light and fast to install. Everyone that I talked to and everything that I read said to stay away from PVC for air. Several reasons have been mentioned here in this thread, explosion, moisture, etc. I believe the total cost with 3 air dryers was under 700 dollars. This is however a lifetime setup.

Adam, good luck with your air. I see you live in the Houston area. PM me if you have time and I would be happy to show you my air setup.
 
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I have the rapidair setup in my shop. I put it in intially, and ran it off my small pancake compressor.

That allowed me to put the noisy beast in another room with two drops in my shop.

When I put in my 60 gallon compressor I had the local farm supply make me an air line out of hydraulic line.

I come off the compressor with an elbow, and a shutoff valve. The hydraulic line fits there and swings over to my manifold. At this point I feed into tha manifold with a drain trap immediately before a large regulator and moisture trap.
In between all components I put a T fitting, and a plug for future needs.

All of the manifold is galvanized pipe, from there I feed directly into a manifold for the rapid air system.

The rapid air blocks for the air drops incorporates a ball valve to drain moisture. I also have moisture traps installed at the drops.

I am pretty happy with the setup. The larger compressor greatly reduced the amount of moisture that makes it to the lines. Most of the moisture comes out of the tank now, since the compressor doesn't run much unless I am going crazy with the die grinder.
 
Pure Oxygen certainly does promote combustion in any material that is used for piping. Pure O2 at pressure is one of the most dangerous gases that you can convey. However in compressed air it is not that dangerous. What was referred to was static charge, and that can be a problem in non conductive piping.

Using copper is probably the best material. Use a good drip leg after the air has cooled and very little water will carry over.

In my location code calls for copper piping to be brazed if using compressed air. I have never seen a properly soldered copper fitting fail but it apparently has. The most likely failure would be the pipe and fitting separating and a very loud noise, but no explosion. The pipe could whip around if not retained but again no explosion.

Using a normal air line would seem to be the easiest as mentioned. If using air drills or other high volume tools use a large diameter hose to reduce pressure drop. I worked for years as a mechanic dragging airlines across the floor. They tangled occasionally but never enough to warrant major changes. The lines I hate are those coiling plastic lines, they tangle every time you go to use them and when you put your tool down it goes snaking across the floor, of course you are on your back under something and can not reach the tool and it is difficult to get out of where you are to chase that **** tool.
The coiling lines also attract anything hot that will melt through causing a noisy leak.

Just keep it simple use good quality hose, the cheap hose tends to get hard when it gets cold.

Bob Parry
 
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