Air lines

[Jack Clay]

I want to run air lines in my shop. My first choice was PVC but after doing some research I found out that it can be dangerous if it ruptures. I am looking at black pipe but am worried about the rust from the pipe. Has any one tried PEX or anything else? I figured copper would be way expense.

[Ken Deckelman]

Black pipe is good, but VERY labor intensive..
If you value your time, then copper is the cheapest, fastest, and less likely to leak.


PLEASE stay away from the PVC:D

[Jim O'Dell]

But get the right copper pipe. Regular copper tubing is almost as bad as PVC. I bet if you take the black pipe, install a couple fittings, you can paint the pipes before installing, and still keep the paint off the threads. Remove and use the fittings as needed. Should keep it from rusting. Maybe safety red??:D Jim.

[Noah Katz]

What's the matter with PVC?

[Chuck Lenz]

Theres allways the option of galvanized pipe instead of black pipe if your concerned about rust.

[Bill Turpin]

Don't even consider it. This has been discussed many times before. Bill

[Jim Becker]

There is a flexible air line available that is similar to PEX but specifically rated for gasses under pressure. Not necessarily easy to find, however. Personally, I opted for copper as it's easy to work with and readily available.

[Mike Jones NM]

Well, I guess I am the odd man out. I use regular air hose, cut and place a "T" at every place you need to plug into. Simple and alot cheaper then black pipe, copper etc. It is also rated for the pressure.

[Bruce Wrenn]

But get the right copper pipe. Regular copper tubing is almost as bad as PVC. I bet if you take the black pipe, install a couple fittings, you can paint the pipes before installing, and still keep the paint off the threads. Remove and use the fittings as needed. Should keep it from rusting. Maybe safety red??:D Jim.I suggest that you go to Copper Pipe web site and rethink your statement. The best way to run any pipe underground is in a sleave, that terminates above ground on both ends. 2" PVC electrical pipe will work for the sleave. You don't state why copper is a poor choice, what gives?

[Jim Becker]

Well, I guess I am the odd man out. I use regular air hose, cut and place a "T" at every place you need to plug into. Simple and alot cheaper then black pipe, copper etc. It is also rated for the pressure.

Yes, that's a viable application. But because it's harder to drain condensation from, it's not always the best choice for a "permanent" solution. I used your method for a few years until I got around to installing my copper lines...worked great relative to delivery of air.

[Noah Katz]

"PVC can CATASTROPICALLY EXPLODE!!!!!!
Don't even consider it. This has been discussed many times before. Bill"

I just did a search on pvc air and +pvc +air and got zero hits.

Anyway, I've had a network of 3/4" PVC pipe for a dozen or so years.

OK, I googled and see the problem.

Came across this interesting aluminum piping system

http://www.transairaluminumpipe.com/

Claimed to be cheaper than copper. Not a price to be found after following a dozen links, so I presume it costs more for materials but less for labor.

[Kyle Kraft]

I agree with you Bruce. Unless you blow a fitting off due to a poor solder joint, the copper pipe is more likely to rupture via an axial split rather than the explosion and ensuing shrapnel with PVC.

[Mike Cutler]

Jack.

Flexible airlines can be just fine as long as they are rated for the pressure. SwageLok is a major supplier of quality flexible tubing used in all industries.
Their products are somewhat expensive, compared to the stuff at home depot, but it should last you a lifetime. Parker is another name

Copper is easy. Most people avoid it because it has to be sweatted together. There is no big mystery to sweating pipe. It's easy, although larger sized Tee's can be a problem due to heat and trying to achieve uniform heat application.

"Black pipe" is not "Black pipe" . Just because it's black doesn't mean its all the same. Some is ok for air systems, some is not. The biggest problem with carbon pipe is getting all the crap out of it. Avoid any pipe that is not seamless.

There are PVC systems that are rated for high pressure application, but you won't find these products in a Home Depot. They are incredibly expensive. They can take pressure in excess of 1000psi easily.
The problem with PVC is the failure mechanism. Copper and black pipe fail over time at low pressure, pin hole leaks, cracks ets. PVC just goes. One moment it's intact, the next moment it's not.

The larger the inside pipe diameter, the lower the working the pressure rating, unless the wall thickness has been changed. There is more surface are inside of a 3/4" pipe, than a 3/8" pipe. At the same given pressure the total amount of force is greater.

Shop air systems are relatively low pressure systems, 100-150 psi. This is why a lot of folks get away with pvc, and less suitable materials. Depending on the piping ID of the PVC, the safety margin can be increased. Smaller the diameter, the more pressure it can take over time.

In all honesty the cheapest and easiest solution is copper when you total up all of the pipe,and fittings, and balance it against long term use and future adaptability. Be careful of the compression type fittings in Home Depot. Some are sized for the applicable "tubing standard" not piping standard, and they all seem to get mixed together. OD on tubing and pipe is different for the same size. Be sure you get the right compression fittings if you go compression.
Copper can also be bent,and not lose it's properties. The bend radius though will be dictated by the manufacture.

I've installed miles and miles of low pressure air system piping and tubing over the past 25 years, in addition to high pressure process systems. It's what I do for a living. The biggest mystery is taking your time and attention to detail.

[Kevin French]

I've got Black Pipe in my shop and garage. With the right tools, which aren't many, the work went quickly. I had a couple air leaks, I now don't have hoses running all over the place now.

[Luther Oswalt]

"PVC can CATASTROPICALLY EXPLODE!!!!!!
Don't even consider it. This has been discussed many times before. Bill"

I just did a search on pvc air and +pvc +air and got zero hits.

Anyway, I've had a network of 3/4" PVC pipe for a dozen or so years.

OK, I googled and see the problem.

Came across this interesting aluminum piping system

http://www.transairaluminumpipe.com/

Claimed to be cheaper than copper. Not a price to be found after following a dozen links, so I presume it costs more for materials but less for labor.

This is unbelievably easy to install but cheap ... I don't think so. I have it in my shop and like very much. I put this in a few years ago and since it is very light weight compared to black pipe I have used in the past. You will need to borrow the "Die and Drill (actually it is a cutter)" they use to drill the holes for each drop you have . Makes this process so much esaier. I have yet to get any water at the drops so that has not been a problem. I just didn't believe the supplier on this claim of no water but so far they have been correct. I got my tubing from a place in Baltimore. MD. since I could not find it down here. I don't know the prices now days so a call to these folks would be in order. Goes up fast!
Leo

[Brent Dowell]

I've got Black Pipe in my shop and garage. With the right tools, which aren't many, the work went quickly. I had a couple air leaks, I now don't have hoses running all over the place now.

I agree with Kevin on this. Picked up a cheap pipe threader, pipe vise, and pipe cutter from HF. Only took a few hours to run about a 30 foot line with 3 drops on it for my shop.

Just make sure you get some sort of flexible hose to connect to the compressor. I got a fat piece of high pressure hydraulic hose from northern tools.

If you go black pipe, make sure you discover the magic of a 'union' fitting...

[Al Killian]

Black pipe is the best choice. It is easy to connect the peices together fairly cheap and parts can be found at any hardware store. Copper is exspensive, needs some skill to solder it to wear it wont leak air and dent easy.

[Noah Katz]

"Copper is easy. Most people avoid it because it has to be sweatted together."

The last time I used copper there were fittings available with an integral ring of solder - just flux, heat, and you're done.

Question on air system layout:

Why slope the piping down away from the air source? That just sends water in the direction where you don't want it, toward the tool.

Why not slope it toward the compressor, where there are already means to deal with it - water separator and drain spigot in the tank?

[Jim Becker]

Noah, you can slope toward the compressor, but any moisture should not go TO the compressor. Rather, it should be caught in a trap equipped with a drain that is below the takeoff for the flexible connection to the compressor. You never want to "send" the moisture back into the compressor.

That said, it's often easier to slope away from the source and provide the same kind of trap/drain at (s) drop(s) that are farther way from the source and the movement of air through the system is also away from the air source...it makes more sense to drain in the the direction of the flow. In larger systems, practically speaking, you will want multiple condensation drains.

[Randal Stevenson]

PVC violates OSHA regulations, because it will eventually split and explode.
If you want plastic, there is one ABS based product (may be several manufacturers), that is color coded differently, specifically for air lines!
Pex, also has a specialty pex, Pex-AL-Pex (if I remember correctly). Pex, with an aluminum "thread" for lack of the proper term. (trying to keep things simple, sorry)

Plastic airlines hold in the moisture, so you will need more dryers (for stain, paint, etc).

Copper (copper.org, I believe), has two ratings that are allowed for air lines (I THINK L & M, but check the handbook). Brazing used to be required (not solder), but as solder has changed, there is one that some places accept (95-5 if I remember correct). The other copper, is rated as too thin a wall.

Black Iron, is the old standby. While moisture is a concern, the biggest moisture culprits are, 1. Not draining the tank, so it builds up moisture and spews it through the pipes and 2. Not angling your lines and having drip valves. The other big Iron issue, is ALSO a copper issue. I've seen people connect them for short runs, without any dialectic unions (two dissimaler metals rust).

Then you have the Exotics, like stainless and aluminum.

For a home shop, you tend to spend either more on the materials, and less time insulation, or less on the materials and more on the insulation. You have to pick what works for you.

[Jim Becker]

L (rigid) and K (bendable) for copper. Theoretically you can use M, but it's a lot thinner and not the best choice.

[Noah Katz]

"Noah, you can slope toward the compressor, but any moisture should not go TO the compressor. "

If by compressor you mean the air pump, I don't see an issue; the lines connect to the tank, not to it.

It just seems a lot simpler to direct the moisture back to one point than to have to deal with it at multiple points at the other end, 8 in my case.

And the tank is full of wet air all the time, so it's not like a new problem is being created.

[Mike Cutler]

"Noah, you can slope toward the compressor, but any moisture should not go TO the compressor. "

If by compressor you mean the air pump, I don't see an issue; the lines connect to the tank, not to it.

It just seems a lot simpler to direct the moisture back to one point than to have to deal with it at multiple points at the other end, 8 in my case.

And the tank is full of wet air all the time, so it's not like a new problem is being created.


Noah.
In absence of dessicant cartridges and air dryers, the % water in the air is going to be uniform once the compressor has run for any appreciable time.
Sloping the tubes to a low point drain, or a fluid air seperator, simply allows you control of the moisture accumulation problem.
You really do want to get rid of it on a periodic basis, either via the drain on the tank, or low point drains in the system. It increases the longevity of a small air system.

[Tom Veatch]

In absence of dessicant cartridges and air dryers, the % water in the air is going to be uniform once the compressor has run for any appreciable time.
...

FWIW, if water isn't removed from the air prior to entering the storage tank, and the input air is greater than about 10% relative humidity (RH), the air in the tank will be saturated at 100% RH for the typical shop compressor (~135 PSIG tank pressure).

[Mike Cutler]

FWIW, if water isn't removed from the air prior to entering the storage tank, and the input air is greater than about 10% relative humidity (RH), the air in the tank will be saturated at 100% RH for the typical shop compressor (~135 PSIG tank pressure).

Very true.
Home systems and lite industrial application generally can't afford to add drying towers on the inlet side that can maintain the correct CV value to keep up. Usually it's just a cartridge type filter, or an eductive mechanical device.
Moisture is generally pretty prevalent in small stand alone units. It's easiest to keep the tank charged and open the drain periodically.
Condensing loops in the headers and or the individual branches can also help keep the moisture down, once again they will rely on low point bleeds/drains.

[Rob Will]

I agree with Kevin on this. Picked up a cheap pipe threader, pipe vise, and pipe cutter from HF. Only took a few hours to run about a 30 foot line with 3 drops on it for my shop.

Just make sure you get some sort of flexible hose to connect to the compressor. I got a fat piece of high pressure hydraulic hose from northern tools.

If you go black pipe, make sure you discover the magic of a 'union' fitting...

Same here.

Rob

[Alan Schaffter]

But get the right copper pipe. Regular copper tubing is almost as bad as PVC. I bet if you take the black pipe, install a couple fittings, you can paint the pipes before installing, and still keep the paint off the threads. Remove and use the fittings as needed. Should keep it from rusting. Maybe safety red??:D Jim.

Beg to differ about copper- check the specs- All three typically available copper pipe (K, L, M) in both drawn or annealed, have working pressures far greater than typical shop compressors can pump. Check out the Copper Tube handbook (http://64.90.169.191/resources/pub_list/pdf/copper_tube_handbook.pdf).

[Noah Katz]

Sheesh, after all that I forgot that I have a dessicant dryer after my regulator/separator.

Though I'm sometimes lax about drying the granules out in the microwave when they're saturated.

[Matt Meiser]

Noah, where did you get a dryer that you can, well, dry out? I'm not familiar with those, but sounds like something l might like with my plasma cutter.

[Noah Katz]

I got it surplus about 20 yr ago; you can see it next to the regulator below the switch box.

It uses silical gel dessicant granules, I think it's the same as what comes in the little packets with a lot of electronics products.

They're blue when dry and turn pink when saturated w/water.

Just heat to "recharge". Takes about 12 min on "high" in a 1300 W microwave.

[Lee Schierer]

We used a system of aluminum piping on the machines we made where I used to work that was an aluminum extrusion and you drilled through the side where ever you wanted and outlet and there was a bolt on threaded fitting that attached via t-slots in the extrusion. You could put an outlet any where you wanted it. There were also various fittings for connecting the ends as well as elbows and such.

It wasn't cheap, but it was certainly adaptable. It is called Simplair made by Ingersol Rand Simplair (http://air.irco.com/IS/product.asp-en-18143)

[Kevin French]

As usual I was lucky enough to find enough black pipe in the dump. Someone dumped a whole system. This winter I plumbed my garage and basement with about 150' of pipe, and eight drops. I also planning to go thorough the walls at each end of the system at some point. Turn out to be a good thing when it came to building my deck this spring. I had to buy a few couplers and a union.