Compressed air distribution in your shop?

I've always run my air lines in black pipe, with a piece of hyd hose to isolate the compressor from the system. The new shop is going to be a combination of black pipe and copper, because that's what I have around. 1 1/4" black for the main runs and polished and clear coated 3/4 and 1/2" copper for the trunk lines, and drops. Pulled several hundred feet of L copper out of a building I was converting from commercial to residential over most of last summer and fall. Seemed a waste not to put it back to work, and hey, it will be shiny! When finished, I will have the combined output of three 80 gal., 5hp, two stage compressors available for heavy duty sand blasting of car frames and such, but 90 percent of the time will just be running one. I think the Rapid air systems are a good, and easy way to go, but I guess I just like the retro look. Here on the island I ran around 100' of 1/2" K-copper for my air, which was nice because you could bend it to go where ever you wanted, which really cuts down on the number of fittings you have to sweat. I think one of the best things you can do when designing your air system is to place your compressor outside of your workspace so you don't have to listen to it. If it has to be inside, a large inlet filter/silencer can help cut the noise substantially. Mike

I am going to be using FastPipe in my shop. Not cheap but I like it. I have all of the pipe, but I am having rotator cuff surgery tomorrow so I am out of commission for about 2 months.

I put PVC in my shop when I built it. Within a year, the fittings started to break. I riped it out & replaced it with copper & have had NO problems in 18 years of use. I was also contracted to repair the air system at a local manufacturing facility. Their PVC air system was constantly breaking, again at the fittings. I put in 1 1/4 inch copper ( just me & could not manage black iron by my self) that solved their air delivery problems. The next move was to install a properly sized compressor & dryer.

DO NOT, I REPEAT DO NOT EVER USE PVC FOR AIR LINES! Very dangerous. I used to work at a startup company that the owner plumbed with PVC air lines. We were always fixing broken lines, owner thought it was funny when a pipe let go with a shotgun blast. We were constantly asking for new air lines but were told the company couldn't afford the cost of shut down and replacement. One day a guy was working at his desk in an upstairs office when he dropped his pencil and bent over to pick it up. Just then a shutoff valve blow off of an air line right outside his window, through his window and embedded it self in the wall across the room! If he hadn't dropped his pencil, it would have hit him in the head probably killing him.

I, along with the other managers (one of which was the guy that almost got killed), immediately shut down the entire plant. We then went into the owners office and refused to run the place until all PVC was removed and replaced with proper iron pipe. The owner no longer thought it was funny and we got our new air lines!

PVC of any schedule doesn't age well in a shop environment, oil fumes and vibration make it get brittle and BANG.

I will get off of my soap box now, that was just a very scary day in my 50 years of working in shops.

PS: I did work in a small shop with PVC air lines after that, when I told the owner the story, he changed out the PVC for copper.

Richard

I went to Pex pipe and shark bite fittings 10 yrs ago....no problems since.

I just want to clarify, I have not and do not advocate Schedule 40 PVC. I don’t think it’s worth using because it does tend to snap too easily and does definitely degrade when exposed to UV rays. Schedule 40 has a working pressure of 200 psi.

But, the Grey Scheduled 80 PVC is a totally different animal because it is not as susceptible to UV rays, has a 800 psi rating, and is much more durable.

Copper type K is by far the best. But pretty expensive and although not super hard to install.... definitely more time consuming than Rapid air or pvc.
PVC IS super easy.
If I was in a rental, knowing what I know today.... I’d use Schedule 80 electric grade conduit PVC.
Might still use 80 if I built a big shop. But, now I’m in a small workshop. I’m using a small Makita 5200 compressor with an air hose. 130 psi is all I need.

Janderso said:

Schedule 40? In a work environment?
Somebody is cutting corners.
That does sound dangerous.
The 1" is 200 psi so the 3/4" is probably 170 or so.
Thanks for the information Tim.

Click to expand...

I think that the bigger the pipe the lower the pressure rating for a particular wall thickness. So a 3/4" pipe would usually have a higher pressure rating than a 1" pipe. (Bigger pipe has more surface area so the cumulative force exerted on the walls of the pipe is higher the larger the pipe is)

I believe the reason to go with the 3/4" kit instead of the 1/2" kit is sustained airflow... i.e. high volume compressed air consumers like a blast cabinet or many people using the same airline. I would guess that 1/2" should be plenty large enough for a 1 man shop.


I just picked up a used 80g 2 stage compressor for my shop so plumbing my shop for air has risen on my todo list. I am thinking of going with 1/2" copper. With my shop layout and the air compressor positioned centrally the max run length will be pretty short and 1/2" should give me more air capability than I should ever need.

I believe the RapidAir line is made out of Nylon. I am pretty sure that in a failure situation nylon will rip instead of blow out shrapnel like PVC. Once I started pricing out all the extra fittings for a rapid air system copper seemed much more reasonably priced for my application.

Yes, bigger pipe will have a lower rating. And if you’re running a body shop which use high volume air tools, or machines like tire mounting machines which use large volumes of air to inflate and seat the bead....definitely 3/4” pipe is better.
For most machinist and general repair shops, we’re just blowing crap and regulating the pressure down to 100 psi or less anyway. So 1/2” is sufficient. Most of our hoses are 3/8” , so 3/4” piping just isn’t really helping you much. It’s all relative.

Back in my youthful days.....everything had to be the “best”
Personally, looking back.....it was a waste of time and overkill. But hey, whatever floats ones boat. I still take pride in my Snap On tool box loaded with Snap on tools. But my god.....they were a damned rip off price wise. Williams wrenches were almost every bit as good....just not as pretty.

Mike, if you own the building... Go with Type K copper. I think that’s the thickest. DON’T use M
Type M is just too thin and is prone to pin holes over time. The only big downside to copper is condensation. Not a big deal out west but in humid areas like New Orleans it’s a big issue. We are constantly fighting water in air lines. Down here we’re constantly draining compressors and need air dryers at EVERY outlet....especially if using a metal air line system. That’s where plastics shine. That’s the only reason I was touting #80 PVC. Cheap and easy to install and no sweating. Dryer air.
And just to be clear....everything I’ve read about Rapid Air has been very positive. Easy to install and works good. And no sweating. But it’s probably proprietary system so every accessory has to be found from a rapid air supplier. But it’s a good system.

Warning people of the dangers of using PVC for air lines reminds me of trying to get my father to quit smoking.

"There's nothing wrong with it, I'm 65 years old and have been smoking 2 packs a day for 50 years and I'm healthy as a horse"

I could not argue this point with him, he was right, never had a health problem in his life.

But then died of lung cancer at 66.

I learned all about how sharp bits of PVC slice and dice when I was young and thought anything close to 3' long was a sword. Leave that pipe for your sprinkler system.

I'm starting to plan the air system for my new building. My dad started using PEX pretty early, and has done some nice air systems with it as he's moved around. I wasn't sure it would be best price-wise, but it turns out I won't need to build a very extensive system, just a few drops around the shop. I'm definitely leaning toward PEX for this job, I'll let y'all know how it goes.