Permanent air lines

[Egon]

I have exactly the same problem. Too small a compressor. The one I have has served me well though. During our last hot days it run for 8 hours straight for a few days when I was scaling rust and painting.

 

[Qapla]

Many of the shops in my area use PVC. Most run the lines overhead (anywhere from 8'-10' from the floor) fastened to the walls with conduit brackets or suspended from the ceiling.

Some use PVC, Black or flex line for the drops to the various outlet stations.

This has been a common practice for at least 20 years.

There have not been any articles on the news about "exploding air lines" and the insurance companies do not disallow the use of PVC.

Perhaps, being in a warm climate (Florida) makes a difference.

 

[Scooby074]

I thought i read somewhere that OSHA doesent allow PVC? Are you guys sure that the plastic airlines in your workplaces are REGULAR PVC and not Nylon, or something else (IE: air approved ABS)?

I was under the impression that PVC will weaken in the presence of compressor oil and vibration.

Quote :The Dallas Regional Office has brought to our attention a potential serious hazard existing with the use of polyvinyl chloride (PVC) plastic pipes for transporting compressed gases in above ground installations. An employee in a Texas plant was injured recently by a rupture in a PVC compressed air line. Plastic projectiles from the point of rupture caused lacerations of the employee's hand. This is noteworthy because the Plastic Pipe Institute, in its Recommendation B dated January 19, 1972, recommends against the use of thermoplastic pipe to transport compressed air or other compressed gases in exposed plant piping. (See attachment.)

Furthermore, sections 842.32, 842.43 and 849.52(b) of the American National Standards Institute/American Society of Mechanical Engineers (ANSI/ASME) B31.8-1986, Gas Transmission and Distribution Piping Systems Standard, limit the operating pressure of plastic piping distribution systems to 100 pounds per inch (psi) and prohibit the installation of such systems above ground except where ". . . the above ground portion of the plastic service line is completely enclosed in a conduit or casing of sufficient strength to provide protection from external damage and deterioration." (Excerpts attached.)



It is our position that PVC pipe shall not be used as a means of transporting compressed air. This position follows the manufacturer's own statements that PVC is unsuitable for compressed air systems. We do allow the use of certain ABS materials that are specifically designed for compressed air systems. One such product is "Duraplus" air line piping system ABS pipe. However, as in any such system, the manufacturer's specifications on acceptable pressure and temperature considerations must be followed.

In closing, misapplication of a product, such as using PVC for compressed air systems, may result in citations and penalties being issued dependent upon the specific conditions.


Source:
http://www.osha.gov/dts/hib/hib_data/hib19880520.html

 

[kennyd]

I thought i read somewhere that OSHA doesent allow PVC? Are you guys sure that the plastic airlines in your workplaces are REGULAR PVC and not Nylon, or something else (IE: air approved ABS)?

You are correct. I posted 2 OSHA links in the thread I referenced above.
But you will ALWAYS have some that say "I have been using it for 10 years without a problem" and that will satisfy some people no matter what the sources you give them. Fact is those people are at more of a risk due to the age of the pipe and possible UV exposure.

Here is more links:

PPFA Bulletin #4

ASTM D1785

Both of those are referenced from the Charlotte Pipe website.

 

[ray66v]

I worked in a shop with PVC, 25 years ago, and have been personally involved in two accidents related to it.

If anyone is going to ignore all the warnings, and use it anyway; use a length of hydraulic hose, or similar, to attach the PVC to the compressor, and switch to steel pipe, before you get to any drops, or attachment points. This will eliminate the most common failure points.

The are so many alternatives now, it makes no sense at all to use PVC.

 

[Scooby074]

The are so many alternatives now, it makes no sense at all to use PVC.

Except cheap Penny wise.. and all that.

PVC is a risk thats really not worth it.

The new 1/2" flex nylon is only $0.75 a foot. Pretty cheap considering. and its approved for air.

 

[MikesTractor]

I have never been around pvc when it explodes (and don't want to be). The city I work for built a new garage about 5 years ago for maintenance on their equipment and vehicles. The air was plumbed with 3/4 pvc. The insurance company and the building inspector both had a fit. Insurance said they would not insure it, and building inspector wouldn't pass it. It all had to be redone with black steel.

Both of my compressors sit outside under a shed. A short 3/4" hose connects each compressor to galvanized pipe on the outside of my building. All pipe on the inside is black steel. I ran my lines around the top of my walls after finishing the inside of my shop with drops at each of 4 workbenches, 1 at my hydraulic table and 1 drop between the 2 big doors. I have 100' of 3/8 hose on a reel between the doors.

Mike

 

[Ken Cunningham]

I allso hated having to pull out air hoses and roll them back up. I hinted real hard about what i wanted last christmas and now i have a spring loaded hose real. Havent had any problems with it yet, but it really doesnt get that much use, but it sure is nice to have. Northern tool has em real cheap.

 

[pat32rf]

I think I will just go ahead and use some of the 1/2 copper that I have laying around. My pump and one resevoir is in the basement (warm) and the second resevoir is at the rear of my garage (cold). I will leave an outlet at the back wall and install a few more at the front where I use most of my air. Tires, impact wrench, blowgun etc
Its not a production setup, I just got fed up waiting for my little portable to pump up when I had my big old unit sitting idle.
I will also stick an outlet in the basement by my workbench for dusting and brad nailer use.

 

[Diamondpilot]

I ran my air lines by coming off my compressor with a 5' piece of standard air hose to a manifold I made out of black pipe. I then ran 1/2" pex to 3 stations in my shop and also ran 1/2" pex back to the house in the same trench I ran my water, electric, phone, and cable tv. In my house it comes in my 2 car garage to a station then on to the furnace room in the house itself. From there it goes up stairs to the closet in the guest bath. It has been real handy to have air in the home. I can do a project and use my air nailers or any other air powered tool along with blowing up childrens toys without hearing the compressor.

Anyway, the pex has held up great. Its rated at something like 220 psi at 160 deg so it will have no problem holding up to the 150 psi my compressor puts out.

Chris

 

[Sockwell]

Regardless of material used, there are a couple of things to keep in mind. This may be common knowledge. If so, I apologize for stating something that is obvious. Both points concern moisture in the pipes.

First of all, the horizontal runs around your walls should not be exactly horizontal. It should have a slight fall away from the compressor, with the last drop being vertically downward with a drain valve at the bottom. By falling away from the compressor, any moisture that accumulates in the pipe will drain to the low end. You can crack the valve open ever so often to blow the moisture out of the pipe(s).

The second point concerns the individual drops themselves. Wherever you "TEE" into the pipe to make a connection point, the Tee should be pointing upward. This will prevent any water accumulation from getting in the connection for your air tools and allow the moisture to flow to the low end of the main pipe. For this reason, my main pipes are run around the shop at about waist level. I Tee upward, with each connection pipe having 3 female quick connectors.

 

[mjncad]

Many years ago I got torqued off about something and threw a 12" piece of 1" SCH40 PVC pipe against a concrete wall. I found shards of that stuff all over the basement. There is no way I would use it for any kind of compressed gas transport.

 

[mjncad]

Regardless of material used, there are a couple of things to keep in mind. This may be common knowledge. If so, I apologize for stating something that is obvious. Both points concern moisture in the pipes.

First of all, the horizontal runs around your walls should not be exactly horizontal. It should have a slight fall away from the compressor, with the last drop being vertically downward with a drain valve at the bottom. By falling away from the compressor, any moisture that accumulates in the pipe will drain to the low end. You can crack the valve open ever so often to blow the moisture out of the pipe(s).

The second point concerns the individual drops themselves. Wherever you "TEE" into the pipe to make a connection point, the Tee should be pointing upward. This will prevent any water accumulation from getting in the connection for your air tools and allow the moisture to flow to the low end of the main pipe. For this reason, my main pipes are run around the shop at about waist level. I Tee upward, with each connection pipe having 3 female quick connectors.

Good advice, and I suspect water in the lines is more of a problem in humid states. I get so little water in the lines that whatever is in the system gets drained out of the tank; but I do have drain valves on my drops wherever possible.

 

[dfkrug]

The OP is talking about permanent air lines, and it sounds like it is a
residence and NOT a commercial operation.

In my workshop, I usually use a custom-made hose reel that I can
crank up my 50 feet of rubber hose in a few seconds. I installed one
permanent line a few years ago, for my plasma cutter at the opposite
side of the building. I used PVC, but not the hard white water lines; I
used flexible PVC air hose. Super easy to install, and works great. I am
NOT in a commercial/industrial shop, so I don't see the need to install
air pipes on the walls.

BTW, the common PVC air hose makes lousy hose for regular use....it is
stiff, esp in cold weather. I use Goodyear black rubber hose for that.
I used to have a self-rewinding hose reel, but it eventually failed, and no
way would it handle 50 ft of hose.

 

[Wineslob]

Good advice, and I suspect water in the lines is more of a problem in humid states. I get so little water in the lines that whatever is in the system gets drained out of the tank; but I do have drain valves on my drops wherever possible.

Yes it is but in our system here in CA we get 5+ gallons of condensate a day. Our humidity is usually in the 15% range. So depending on how much air you use it can and will vary, but it will always be there unless you get rid of it.
I've been designing and installing compressed air systems for 20+ years. All have been commercial. The one I installed at work is in a 100,000 sf building. The entire perimeter is in 2" black pipe with 1" branches and 1/2" drops. Our main compressor is 100HP and can provide over 400 CFM @ 120 psi.
You can use some of the "rules of thumb" for a small system installed in a garage or shop.

You can use copper but, as has been stated, use heavier schedule pipe. The preferred pipe is schedule 40 black iron up to 2". Any bigger and copper is eaiser to work with. Never use galv or PVC.
Anytime you can, do a perimeter loop, it will insure that from any drop used you will get maximum air flow.
Always halve the drops compared to the mainline IE: Mainline is 1" use 1/2" drops.
If you can, invest in a drier, even if it's the one from HF. Water will kill air tools, and ruin a paint job. At the very least get a filter with a auto drain.
As has been stated use "T's" and go up and over and back down on the drops.
You will always need more CFM than you can afford.

 

[Bigkrank]

Copper is great for air but your insurance agent won't like it. Have a fire and solder melts and you have compressed air feeding the fire. This is also a second reason they don't like PVC besides the exploding factor.

Black iron is the only thing they don't frown on around here. I never asked how they felt about the Garage Pack aluminum stuff with the easy assemble fittings.

 

[kevinj]

Copper is great for air but your insurance agent won't like it. Have a fire and solder melts and you have compressed air feeding the fire. This is also a second reason they don't like PVC besides the exploding factor.

Black iron is the only thing they don't frown on around here. I never asked how they felt about the Garage Pack aluminum stuff with the easy assemble fittings.

Around here we braze copper just like we do for high pressure refrigeration. I would not use soft solder for air service.

 

[schmism]

When PVC fails it fractures into semi-sharp fragments which are propelled throughout your shop by the compressed air. PVC is not rated for air pressure for this reason. They can be big pieces and propelled quite fast.

last i checked the PVC is just pressure tested to some PSI. air, water it really doesnt matter.

PVC under 100PSI of water pressure will exhibit the same failure type as 100PSI of air.

Other than its increased propensity of failure due to external forces, if such forces are limited the advantages of its ease and speed of installation, and cost can be compelling.