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.