ramtuff

Member
I think i need to replace my 1/2" pvc central air line system?Never had any problems in 25 years with it,but from what I read probably to replace it.What would be best to replace it with. Thanks in advance.
 
Not sure why you think you need to replace your
PVC. Our shop runs 175 psi on 1/2" PVC and the only failure we've ever had was next to our furnace where it got way to warm.
 
(quoted from post at 01:31:25 01/19/14) Not sure why you think you need to replace your
PVC. Our shop runs 175 psi on 1/2" PVC and the only failure we've ever had was next to our furnace where it got way to warm.
Using PVC for compressed air is extremely dangerous.
If you break a pvc line that has liquid at 175 psi you just have liquid spraying out under pressure. The problem with using pvc for compressed air is if the line breaks the air expands and you can get hurt or killed by pvc shrapnel.
 
If it is schedule 40, and you don't have real high pressure in it, all the time, I would just replace any pipes below head level. Water in them that freezes, and they can blow up into a million pieces, under pressure. If you have people other than just you in the shop, it could be a liability/insurance issue.
 
No reason,other than what i've read on it.Runing about 160 lbs on it the lines are about 10 ft high.I could put 1 1/2" on it for a safety cover would that work do you guess?
 
We had a PVC fitting blow off a pipe and it glanced off my shoulder and hit the opposite wall of the shop. No, I was not tugging on the hose. I was starting a mower near the far wall at the time.

My vote is for the galvanized pipe.
 
How long is the total run and how many outlets do you want to have?

Soldered copper is fairly easy to work with, but has become pretty expensive. Threaded black or galvanized steel pipe is harder to work with and is also quite expensive these days. The metal pipes have the advantage of being able to radiate some of the heat from the compressed air, making it cooler at the end of the system and dryer because more of the water condenses out. The metal pipes also are less likely to have problems from the oil in the compressed air. However sooner or later steel pipe will rust from the moisture and that might lead to leaks and flakes of rust and/or galvanizing zinc in the compressed air.

These days lots of new houses water supply pipes are being done with PEX. I don"t know of anyone who has tried using PEX for air lines, but the idea is appealing as PEX is lots less expensive than the metal pipes, even considering the costly fittings needed for PEX. It would be interesting to learn if the PEX manufacturers would recommend PEX for air lines, or if there is a problem in doing that.

Around here, most of the smaller underground natural gas lines are made of some kind of fairly flexible plastic. In talking to workers from the gas utility, they like the plastic lines because they are so easy to work with, and never rust. Maybe something like that could be used for an air line system.

But none of the plastic line choices would cool the compressed air as well as metal lines. And I would want to be assured by the manufacturer that their plastic product would not react to the oil and moisture inside the lines adversely over time.

I have a 1" copper main line in my shop that I put in years ago. It works fine, and the way I built it, the condensation mostly drains down to the lowest part of the sloped system, making drainage easy. The only time I have had problems with it was before I got the shop all insulated, and the drainage sump froze and cracked. It was easy enough to replace though. I suppose it would cost well over $500 to replace the whole copper main line today. Still, I think copper is the best over-all choice. Good luck!
 
Insurance inspector walked thru my shop when I first insured it. I had a couple temporary PVC air lines run from the compressor across the ceiling to the other side of the building. There was no mistake that they were for air. The inspector pointed at them and said "I expect when I come back next week and check, those 'conduits' will be of proper material". They turned into permanent 3/4" black steel pipe that week. Don't matter what works, it's what is correct that matter to lawyers and insurance people.
 
I researched this issue for my shop as I am plumbing the whole shop for air.

Pex is not approved for air, pvc is not approved and can be dangerous, black iron can rust and contaminate the air, galvanized can have problems with zinc flaking off and contaminating the air.

This leaves the plastic kits from northern and such, stainless, and copper.

I am using copper for my shop.
 
I ran my air line in pex and it worked out great.
I talked with the manufacturer and they assured me it would work just fine, I ran mine behind the walls and the psi is 175.
 
I put 3/4" Rapid Air Maxline in my new shop, it also comes in 1/2". It is a little stiff to uncoil but looks nice when done, also the plastic clips in the kit are kind of a joke so I used plumbing straps. I was advised against sch.80 pvc, dangerous and not osha approved.
 
(quoted from post at 18:21:20 01/18/14) I think i need to replace my 1/2" pvc central air line system?Never had any problems in 25 years with it,but from what I read probably to replace it.What would be best to replace it with. Thanks in advance.

This is what I did and very pleased. I have 4 outlets; 1 at each rollup door with retractable lines; 2 on opposite walls with 3 qd connectors. I only use my air occasionally so it meets my needs. Your mileage may vary.
http://www.rapidairproducts.com
 
Find a Parker Hannifin distributor in your area. I used their Parflex nylon tubing which has a working pressure of 250 psi and goes together with push lock fittings. When I buried the electric service to the farm buildings, I pulled tubing along with the wire in the underground conduit. I now have compressed air set up in every building being fed from one compressor.
 
I just needed one outlet since my shop is small. So I ended up buying an air hose and sleeving it in PVC pipe to keep it straight and rodent proof. Works good, safe, and inexpensive.
 
Wow, I'm amazed you got by 25 years with PVC! I've seen it used in a couple of shops and within a couple of years it was failing. Serious failure as in sending daggers of splintered plastic flying across the shop!

I plumbed the shop I work in now with galvanized pipe. Everything slopes back toward the compressor, all the drops come off the top of the line and 90 back down. (Another advantage of coming off the top and using 2 90* ells, it gives flexibility to the drop line if it gets pulled or hit be the forklift.)

Also all the runs are 10 ft. max, coupled together with plugged tees for future use. All the 90's on the run lines are also plugged tees.

I still get a little water in the summer (air conditioned shop) but were looking to upgrade the compressor with an aftercooler soon.
 
The roll of PEX I have left over from the floor heat is only rated for 125 psi, I run 175.
 
Boss plumbed his shop with PVC. I'm not worried about the pipe blowing apart. The joints above the ceiling blow off every time you open the shut-off more than enough to just hear the air hiss by.
 
PVC is not to be used for air pressure lines, OSHA even says so.
I think PEX is rated for air pressure, you would have to check.
The temperature extremes make the PVC brittle, especially the cold and then BAM ! It ruptures and flys all over like shrapnel.
When in doubt use black pipe.
 
Most of us think of the stuff you can buy at Home Depot when we say "PEX". The product you linked to is actually PEX-Al-PEX, which is an aluminum tube sandwiched between two layers of PEX. It's not readily available at plumbing stores, let alone big box retailers. It is also nearly as expensive as black pipe.
 

You guys need to read Greg K post again. He only used the PVC for a sleeve, the PVC is NOT under pressure.

Dusty
 
I plumbed my shop airlines with 3/4 PEX. At the time I was working on the walls so ran temporary lines with Sharkbite fittings. Well you all know what temporary means and those fittings are still in place. I have never had any problems with the lines or fittings. PEX is easy to change things, I need to add a line by the man door. Cut the PEX, add a fitting, run a line, done.

As for gas lines, we built a house this last summer. The wife was worried about how close the propane tank was to the house so I moved it to the edge of the driveway to the shop. It is about 75' from the tank to the house then another 90' to an outbuilding where she has a sewing room. It was all done with Poly pipe and Sharkbite like snap fittings.
 
Follow Noah's link above. In the middle of the referenced page is a set of tabs. Click on the one that say "Info and Guides". Then click on the tab that says "Product Information: How To Guide". Scroll to page 6. You will find the following warning:

"Testing with or use of compressed air or gas in PVC / ABS
/ CPVC pipe or fittings can result in explosive failures and
cause severe injury or death.
• NEVER test with or transport/store
compressed air or gas in PVC / ABS / CPVC
pipe or fittings.
• NEVER test PVC / ABS / CPVC pipe or
fittings with compressed air or gas, or air
over water boosters.
• ONLY use PVC / ABS / CPVC pipe for water
or approved chemicals."

There it is, straight from the manufacturer. DO NOT USE PVC FOR COMPRESSED AIR.
 
I used hydraulic hose in my shop. It might not be the cheapest route but it's easy to work with and will last forever.
 
Look at the RAPID AIR kits that the guys below are talking about. I have installed two of them in the last few months. They work great. I really like the aluminum wall brackets with the built in water trap/drain.

The 3/4 three drop, 100 foot line kits are at Thiesen's for $199
Rapid Air kits.
 
the machined aluminum blocks in the kit are really nice, I put a brass T above it to get an extra outlet, one for a hose reel and the other for a 1/2" hose for a 3/4" or 1" impact
 
I am aware of the points you make.

HOWEVER, in response to the original post it IS a type of PEX and it IS available.
 
Yep the dark gray schedule 80 pipe is ok with air.

Schedule 80 PVC pipe can be threaded and 3/4 inch is rated at 690 psi. 1/2 inch is rated at 850 psi.

Threading the schedule 80 PVC does derate the pressure by about 50%.

I know several people who use this for high pressure air applications.
 
(quoted from post at 02:16:45 01/21/14) Yep the dark gray schedule 80 pipe is ok with air.

Schedule 80 PVC pipe can be threaded and 3/4 inch is rated at 690 psi. 1/2 inch is rated at 850 psi.

Threading the schedule 80 PVC does derate the pressure by about 50%.

I know several people who use this for high pressure air applications.
Is it rated for compressed air/gas or just liquid? I've never heard of any PVC rated for compressed air/gas.
 
I think D1784 ATSM spec is for pressure and D1785 if for pressurized liquid only.

Just off the top of my old bald head though :)

later edit:
Hmm keep finding warnings about pressurized gas is a no no.

Guess my old bald head is wrong.

But I do know of several using it for years with no problems.
I like the no rust thing and low condensation factor.
 
Iron pipe or the Rapid Air System. Rapid Air is the easiest of the 2 to install unless you have a pipe cutter/threader.

Regardless, any type of pvc pipe is not intended to be used for compressed air. All the manufacturers have warnings about it. I heavily researched it before I installed mine. I was going to use pvc until I read all the horror stories. It might last 10 years, then one day a big blast that could kill someone. Not worth the risk.
 
The preferred industrial air lines are Transair aluminum. Where I work we have 2 Kaieser 150 cfm. rotary compressors, a 1000 gallon tank and a cooling unit. Feeds about 5 acres of buildings. Hundreds of air powered sorters and separators all running at once.

The entire system is Transair aluminum from Parker. Fittings are made of high grade plastic and metal. The connections are push in and are also removable. Can be live tapped anywhere you need a drop. All aluminum and plastic so rust is impossible.
Expensive, very! but it is 100% Osha/Insurance compliant and will last longer than your shop. We have to replace rubber hoses that have cracks in their outer covers, and hoses cannot have push on ends, they have to be crimped or the safety people go crazy. I "threw away" 25 perfectly good 50' hoses last year. ( right in the back of my truck) They cannot ever find issues with the Transair and I think it drives them crazy.
http://www.transair-usa.com/
 
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