What did you use for air supply line? Pex, copper, black iron?

honda
accord

#1

Been using a hose and reel off my shop compressor. It was located in a good spot and this worked fine. Just step over hose. I moved compressor about 50 foot and want to run new line. I’m putting in water sep. and filter. I’ll have about 4 drops. I think I want to use 3/4 PEX. I have used it in plumbing for years and it is tough. I cant see where there is a downside. The kits you buy are sharkbite style and I think the crimp on pex is superior. it is rated at 150 psi at 100 deg. I will have to cover pipe because of uv damage. I run regulator at 110 psi or close to it. I know this PEX does not have an oxygen barrier and I wonder if air molecules may seep same as old a/c lines. Any thoughts?


#2

Schedule 40 pvc was very satisfactory with shop pressure at 175 psi. One break in 20+ years.


#3

Was my first choice, but OSHA and local gov. says NO. I’ve seen that alot but don’t know if I should risk it after hearing a few horror stories. WOW one in 20 years. I’d go to Vegas with that. Thanks


#4

It would appear that I installed mine before anyone mentioned it wouldn’t work and somehow got lucky. Installed in 1983 and still there. I’ll warn the new owner to be aware.


#5

Copper??


#6

Thick wall copper is said to be good because the moisture in line will not rust like iron.


#7

PVC is a bad idea, it fails violently sending plastic shrapnel over the area.
Copper is great - but expensive.
Black iron will rust over time - but it’s cheap.

PEX? 150psi is too low (and I assume that is static pressure), not to mention the problem will be on a 40 degree day (inside a shop?), not a 100 degree one.

I’d aim for at least 2x over whatever pressure you intend to run (125-175 psi working pressure is normal).


#8

Shop air compressors have been plumbed with copper pipe for 100 years without any problems…Why go looking for problems now??


#9

The higher the temp the less it will handle. At 40 it is higher. It will instantly burst at 600 psi I believe.


#10

The Rapidair kits are rated at the same as Pex the best I can tell. The other option is DOT tubing used in Air Ride suspension but I’m not sure where to get all the fittings.


#11

What does OSHA say about schedule 80? That’s rated at 200psi.


#12

i work on air compressors and car hoists as well as associated shop equipment.
black iron pipe is still the standard for most places as its fairly cheap to purchase pipe and fittings and easy to install using unistrut and clamps (do have to cut and thread pipe but as a plumber you know this) almost all state shops etc do it all in solderd copper but they have access to lots of our money so cost is not a issue .
i personally used thinwall seamless highpressure pipe cut and threaded.
there are concerns over rust in pipe but using a water trap and draining both compressor and trap and changing the filter in the trap will stop most of that also putting drop legs on each drop with a ball valve will allow a place for sediment etc to be trapped.
depending on what air is used for a inline automatic oiler can also help
most kits sold are expensive due to ease of install with no threading or soldering for average home owner.
i assume you want to use pex becouse you have it and its easy to install also. however is it worth it if you have to protect it and then have the added hassle to mount it so it looks nice and then would need to change over to ridged at each drop inorder to secure it so you can hook and unhook hoses without bending or twisting pex each time .
another thing is what type of compressor, single stage 0-125psi or two stage 0-175psi a failed regulator on a two stage could allow higher pressure than pex is rated for.


#13

2 stage 155psi. 5hp 80 gal.Good point on regulator. I liked that you could fill pex with water and freeze and it will expand without rupture. Figured that quality would buy some time in a failure. It is TUFF, but I don’t want to regret it later. Thanks again. Ed


#14

I use copper and no problem for years. Don’t know why you would want to risk it with something else for a few dollars difference. Black pipe is popular in body shops for the heat issue is all.


#15

well what did you use?