Compressed Air Piping

[dieselsmoke1]

I need to run a couple of air bibbs around my garage before closing in the interior walls. I can't, or more more specifically do not want, to bore through my corner posts or LVL support structures so it's over the top and back down. Hard pipe like galvanized is out, got to have something flexible enough to work through existing framing. 150 PSI max. PVC? PEX?

 

[westcliffe01]

PEX seems to be max rated at 100PSI. I would imagine PVC would be even lower. I would stay away from PVC for sure, PEX is pretty tough stuff. Remember that water travels with air, so really everything needs to be sloped like plumbing and air takeoffs need to come out the top and not the bottom to block the water transmission as much as possible. If the run is long, you may want to add a reservoir at the end you draw from to improve the system response, else pressure will drop as soon as you start consuming air.

Skipping details on permanent air lines can reduce the quality of your experience substantially, particularly if you want to paint anything or use a plasma cutter, all of which are moisture sensitive.

 

[LD1]

You should be fine with PVC. Just plain old sch 40 PVC. I have used it before and have seen it used several times with air.

3/4" pvc has an max operating pressure of 289psi and a burst press of over 1500psi. So you shoudn't have anything to worry about.

Here's a link to different sizes PVC Pipes - Pressure Ratings

I didn't see it mentioned in that link but there are two kinds of PVC pipe. Theres the good kind that is solid PVC, and then theres stuff with a cellulos core, I'm not sure the technical name, but it usually has a lower rating.

Also, most all PVC has pressure ratings stamped on it, so if you go to lowes or something, just look at the lengths of pipe and it says what the rating is.

 

[Red Beast]

PVC for sure. A mate who does mechanical work, and spray painting in his shed at home has PVC run around the walls for the air.

 

[westcliffe01]

Well, I stand corrected. Just consider the highest inlet temperature from the compresser. the link posted had this note:

Note! The maximum operating pressures derates with temperature. At the maximum operating temperature for PVC - 140oF (60oC) - the strength is derated to approximately 20% of the strength at 73oF (23oC).
Be aware that maximum operating pressures varies with the fittings design. Consult the manufacturing data.

 

[timswi]

I ran sc40 PVC in my last garage for the same purpose as you need...Used it for 10 years hooked up to a 60gal 220v 135 max psi compressor...never had a leak or blowout. As was stated, make sure you have proper sloping and a water seperator a fair distance from the compressor to allow the air to cool.

Also, hook up a flexible hose (high quality) between the compressor and the beginning of the pvc run to keep the vibrations and movement away from the pipe.

I've heard that this is an absolute no-no, but it does work. If installed properly.

I didn't want to use galvanized or steel because of the rust and sweating possibilities..At the time I was doing high-end car restorations, and debris would have ruined my day.

 

[CurlyDave]

The debris from a burst PVC pipe will definitely ruin your day. Maybe even the rest of your life.

There have been other threads on this subject.

There are two problems I see. One is that the temperature may well get pretty high if the pipe is run overhead. 130 degrees is not unusual at all in an attic space.

The second issue is that PVC can be shattered. Imagine something falling against one of the air outlets.

I would run surface mounted iron pipe. Yup, it will be ugly and possibly in the way, but you are talking about a garage, not a living room. And it will be safe.

 

[FallbrookFarmer]

The debris from a burst PVC pipe will definitely ruin your day. Maybe even the rest of your life.

There have been other threads on this subject.

There are two problems I see. One is that the temperature may well get pretty high if the pipe is run overhead. 130 degrees is not unusual at all in an attic space.

The second issue is that PVC can be shattered. Imagine something falling against one of the air outlets.

I would run surface mounted iron pipe. Yup, it will be ugly and possibly in the way, but you are talking about a garage, not a living room. And it will be safe.

Ditto
Lets see, a little overpressure, a little knock with something hard. How do you spell shrapnel?

 

[timswi]

Curly,

I wasn't aware that he was running it in an attic..Anyway, hot water tanks run at 125+ degrees for decades in PVC.

One of the reasons that I recommended rubber hose before the PVC. It insulates the PVC from movement and also allows a degree of cool down.

I guess it could get smashed with something, not something I've experienced since I kept the pipe out of harm's way with the connectors steel clamped to the walls.

Appearances were never a concern of mine..I was concerned about rust in the lines, which I have experienced with steel pipe..Takes forever to get rid of it.

You're right it's a garage..Different strokes, I guess

As far as overpressurizing, I make sure that the blowout on the compressor is working. A blowout on a rubber line can put a hurtin on you as well..Been there with that one.

Not trying to sell this approach, just sayin.

 

[CurlyDave]

Anyway, hot water tanks run at 125+ degrees for decades in PVC.

Water does not compress. Very little stored kinetic energy. Air is compressed, lots of stored kinetic energy.

 

[timswi]

Anyway, hot water tanks run at 125+ degrees for decades in PVC.

Water does not compress. Very little stored kinetic energy. Air is compressed, lots of stored kinetic energy.

I was referring to working temperatures..You're right about the kenetic energy.

I agree with you..PVC wasn't designed for this, but the burst pressure and temp fit in the ranges and I have used this without issue for years, with a little care and common sense it works. As I said, I'm not selling this as ideal. Please, don't take me the wrong way, I'm not trying to argue, I agree with you in general.

 

[Cami]

@westcliffe01: The remote receiver is an awesome suggestion; especially with tools that take gulps; even little ones. A construction company I did some welding for had problems running nailers a long way from their compressor. A small, portable receiver on whatever floor they were working on fixed things up nicely.

There are a few ways to meet peak demand at the end of a long run of pipe. What come to mind are upping the pressure, laying bigger pipe, or the remote receiver. The remote receiver is easy to install and can be had on the cheap, but upping the pressure raises your electrical bill, and bigger pipes are more time and money...and is definately overkill if it's to supply an intermittent demand.

As for what to use to transport that air, I've dealt with black pipe for others, but for myself just run air hose; easy and cheap. How can a self-respecting welder not use black pipe in his own shop? I still haven't figured that one out

 

[Bedlam]

could you explain a remote receiver please?

 

[RickB]

Anyway, hot water tanks run at 125+ degrees for decades in PVC.

Water does not compress. Very little stored kinetic energy. Air is compressed, lots of stored kinetic energy.

Additionally, few domestic water systems operate at over 100 PSI, hot or cold.

I would not use PVC under any circumstances.

 

[kennyd]

PVC is just plain dangerous for air,so much so that OSHA has banned it. Plenty will say "I have been using it for years..." but that is bad advice.

Do some Google searching, terms like "PVC for air" and the like, I don't have the links here at work-but if you search my name and "PVC" you will find a lot of OSHA links I had posted in the past.

 

[The Haymaker]

I plumbed my shop with PEX, and have no complaints. There is PEX rated over 100psi.

I looked at it this way, if pex can take the pressure along with WATER HAMMER involved with the mass of water, then I knew it would take air, which always runs cool.

Love it, works awesome, and is slick when the time comes to add a T somewhere.

PVC on the other hand..... After having a couple air cannons made with the stuff and let go at 120psi, I'd recommend staying away from it. The stuff disintegrates and leaves razor edged shrapnel over a fairly large area.

 

[GE222]

I strongly agree with CurlyDave. Using PVC is a very dangerous mistake. When PVC fails, it will blow shrapnel everywhere. Even in perfect temperature conditions, I would never use it.

Steep pipe has a big secondary advantage in that it will cool the air which will condense the moisture into a drip leg, before it reaches the tool you are using.

A filter should be installed just before the air quick connect, so rust should not be an issue.

I have never used PEX tubing, but if it does fail, I believe that it would simply tear, or a joint would fail.

 

[tomnky]

There are build Your own solutions that look pretty good to me. Here is an example: Compressed Air Piping and Air Tools from Garage Pak


http://www.transairaluminumpipe.com/?gclid=COm_p-Glu4sCFQVAgQod9nXaxw

http://www.rapidairproducts.com/

 

[Egon]

Do a search on Google. You will find there are now flexible plastic lines available for air service.

It's just a mater of locating them locally.

 

[GE222]

A remote air receiver is simply a second air tank usually mounted some distance from the main compressor/air tank. They are often mounted near a load that has a high peak air consumption. The tank will supply the peak load, instead of waiting for the air pressure to recover through the supply line.

Large industrial plants employ this practice all the time. For them it will often allow one compressor to be shut down, assuming that they have more than one, which many large facilities do. Air is a very expensive commodity.