Garage air plumbing/electrical

[Bakins]

I finally got around to properly doing the air lines in my garage. I did it with black pipe. PITA. I planned it so I could use mostly pre-cut lengths. It was still a major PITA. Only had two leaks - one in a union that's slow and I have yet to get fixed.

I now wished I'd just spent a little more and did it with copper. Much easier to work with, IMO.

I also did a sub-panel a few months ago in the garage for the compressor, welder, etc. I just ran conduit on the walls. This was 100 time easier than the black pipe for the air. I have a 220 for the compressor, another 220 for the welder, a 120 for the welder (I have a miller dual voltage welder) and another miscellaneous 120 circuit. I had a length of wire that was just a few feet short :( 6/3 ain't cheap...

Did I mention I dislike working with black pipe :P

[Run-em]

Let us know how you really feel about the black pipe! Don't hold back.....it isn't good fer ya!

[Rick_L]

To each his own, the black pipe is easier for me.

[Bakins]

This was the first time I'd ever worked with black pipe. I guess I'm just more familiar with copper.

[Run-em]

Now ya just need to add the power for the heat/air unit, the refrigerator, microwave, T.V. wiring, T.V., and a bar! When do we get the invite to the party?

[Bakins]

Now ya just need to add the power for the heat/air unit, the refrigerator, microwave, T.V. wiring, T.V., and a bar! When do we get the invite to the party?

Nah, I got all that in the basement ;) I wished I'd had the garage insulated. I would probably put in a window AC unit - it gets uncomfortably hot in there sometimes.

[Tabasco]

OK, I know I'm doing it wrong and it is going to blow and kill me (I read that on the internet), but I plumbed my air with PVC. I've done it in 4 shops in the last 35 years with no problems. It is a lot easier and cheaper.

My PVC is eight feet up with black pipe for drop downs. Maybe the PVC is high enough when it blows up it won't kill, me just severely injure me.

[Bakins]

I've read too many PVC horror stories to even risk it. I thought about some of the "rapid air" stuff for some long runs, but haven't needed that yet. I still can't get one union to not leak and its driving me crazy. I may rip is all out and redo it with copper. Yes, I'm crazy ;)

[warren57]

Ahhh PVC. I won't get in to the elasticity of PVC and how it expands to a maximum point (like a balloon) just before it explodes and send millions of PVC splinters in every direction. They penetrate drywall and anything in their path. If you're still around, will keep you busy cleaning up for some time.
If you want an actuasl account feel free to contact Ford High Altitude Emmissions Lab in Denver. I blew up a substantial amount of4" PVC containment piping while air testing it (as a mechanical contractor). Thankfully no one was in the room at the time.
Be careful... don't exceed the rating, it doesn't just spring a leak!!!

[chevynut]

One thing to keep in mind is that smaller tubes with the same wall thickness will take more pressure before exploding. I'm not sure how that factors into using PVC, but I'm pretty sure there's some out there that's safe at higher pressures.

[Rick_L]

The problem with PVC is not the strength or burst pressure of new pvc pipe, it's what happens to it as it ages, especially if it's subjected to heat and cold cycles. Think of it as chemical fatigue. The heat comes from the temperature of the air in it, but the cold can just be an unheated building in the winter, even if it's temporary. That's aggravated by bending stresses due to the pressure, if the tubing is not clamped to a wall and is allowed to deflect under pressure.

There are plastic tubes that are rated for compressed air, of course they cost more than PVC.

[bigwrench]

Could use CPVC, its stonger and off white

[567chevys]

Hey Guys

Never used PVC pipe for compress air , They make a PVC type pipe or tube that has fiberglass in it . the problem with PVC pipe is when it get hit with any impact it explodes like a bomb
OSHA will write a ticket for the use of it but thats only in a bussiness place
Dont be cheap buy plastic tubes that are rated for compressed air

[warren57]

A lot of people say the moisture will feed rust, you'll get dirty air , etc. What they fail to realize is their air tank is made of un-coated mild steel, just like black pipe A-53 grade as I recall... It will work good and last forever...

[Rick_L]

"It will work good and last forever..."

There are plenty of air comressor tanks that have rusted out over the years. You have to maintain your air system and drain the tank often, otherwise it will rust and pit.

[warren57]

I agree with Rick, it's critical to keep you tank blown down and drained. And of course forever at my age isn't that long. For younger guys, you made need a replacement tank!!! Not sure why all the compressor tanks around Rick's area rust out, but in my 61 years I have yet to see one in Colorado. I imagine the hot, humid air in Houston might play a part in rust. Also, I'm sure non rated tanks are designed with varying thicknesses of steel, while (at a higher cost) you can get a rated tank which is standardized per govt. spec. None of this plays into black pipe, as sch. 40 black pipe is made per a govt. spec. therefore steel thickness is standard. There is a difference in type of black pipe. Seamless is likely the best choice, but more expensive. ERW (elect. res. welded) being the least expensive with a seam that is visible. In some import pipe I have seen this seam leak when new. On one school project we installed (as a mechanical contractor) we actually had to weld portions of the seam with the pipe in place to get it to hold pressure. Normally not an issue with US pipe.
I'm sure it will last you for years, likely longer than your compressor will last!!
Good luck (also on that union, apply a coat of pipe dope on the face/seat. On joints, wrap with teflon tape and coat that with pipe dope. You'll rarely have any leaks. Also, don't over tighten mallable fittings, they stretch...)

[stroker]

chevynut is right. Smaller diameter pvc has a high bursting strength. I plumbed my shop for air with 1/2" pvc. eight years ago. My compressor puts out 175 psi and working pressure of 1/2 pvc is 250+ with a bursting pressure close to 1800 psi. Being inside it's not exposed to uv so should last. I do however open the valve slowly to pressureize the system.