Fellas, Can I use copper for compressed air? thick or thin wall? I will make my drops in black pipe for more support. I just have some copper and it will save me alot of $$$. What are the positive and negatives, do’s and don’ts.
Thanks, Lou
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Replies
This has been covered on here before. IIRC, the general consensus was that copper is OK for air at normal shop pressures. You can do an archives search if you wanna spend some time reading.
But, since I have no firsthand knowledge on the subject, the real reason I responded was to note that I haven't ever seen a post that claimed "using copper will save me a lot of $$$"! I guess if you were using gold or silver tubing, that would be true, but . . . .
Heck, you could probably sell the copper for scrap, buy iron and still come out ahead.
;-)
Mike Hennessy
Pittsburgh, PA
Lou
Our shop has been using copper for compressed air for.........well, forever! Our drops are also copper and never a problem, your not going to pull it apart. I doubt that it makes a difference if its the thin wall or thick.
I worked at a place down in TX and all their air lines were PVC, scared the shid out of me, never use that stuff, if it blows there will be shrapnel everywhere.
Doug
DougU,Did the PVC ever actually blow? Perhaps you were the only survivor? Just curious where that fear came from;>gk
Years ago my dad, an auto bodyman for many years but new to body shop ownership spec'd PVC for the air lines in his new shop. One blew a couple of years later and it was exactly as DougU described, shrapnel everywhere. Luckily no one was hurt but all the lines were replaced with iron soon after...
Does that mean my PVC potato cannon is a liability?
Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read.-Groucho Marx
Edited 12/20/2007 6:22 pm ET by musashi
Yes.Ship it to me, and I will dispose of it properly.;o)
A man, convinced against his will...
Is of his own opinion, still.
~Anne McCaffrey
DC
Its been documented, numerous times, that pvc can/will blow and when it does it sends shrapnel everywhere.
I believe that it is against some code, it was discussed here a few years ago but I don't know the specifics. Hope I'm not stretching the truth on this but I do recall someone mentioning that it did violate some code/recommendations.........maybe OSHA, not real sure anymore.
Doug
Worked for many yrs in an industrial laundry, we were once cited by MIOSHA (Michigans version of OSHA) for having a couple short pvc runs. Most lines had origonally been black iron & high humidity conditions had caused a lot of interior corrosion. We replaced them all with copper, I wouldnt use anything else.
The previous owner ran PVC for our compressed air lines. It blew up. I had it replaced with galvanized iron pipe.For my home shop I will run copper since it is easier to work with.Download the copper handbook from copper.org and they tell you all you need to know about using copper for compressed air.
Great site, lots of good info.
Thanks for the link.
According to table 4 on soldered connections for compressed air, at 250 degrees a solder joint in 3/4 pipe is good to 270 psi.
------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
Copper is good and I would use it all the way.
The black pipe can cause rust to form and gum up your lines.
Type L copper is fine, don't know first hand for Type M copper.
Somewhere in the archives there is a link to a max pressure table for copper - don't know where it is - 1/2" and 3/4" L max pressure is way higher than you would think.
Black iron or galvanized for drops - OK.
Make sure you install drip legs on the drops - best if you install a valve for draining on each leg.
Ball valve works the best with the valve oriented vertically as this allows the air to blow any crud out of the line easily when drained. Leaving the valves open when the system is not in use will allow the lines to dry.
Jim
In a nutshell--------- yes.
Copper is just fine, it can handle more pressure than 95% of all air compressors can put out.
"Why do you hurt me when I do bad things to you?" My youngest son to his older brother
Does he need di-electric fitting at his black iron drops?
Dave
No, if it was a water system then you could get electrolyses between the dissimilar metals, but air systems do not require isolation of the two different materials.
"Why do you hurt me when I do bad things to you?" My youngest son to his older brother
Most if not all PVC manufacturers state "Not to be used in compressed air service." This statement is in the catalog and installation instructions.
Hey guys,
Don't have any plans to, but---- what about PEX for air lines?
Aside for the sagging on long runs issue, it looks like it should take
the pressure.
Anyway, just throwing it out there to see if it will fly.
Canoedog
My air lines are in pex.
The pex companies recommend testing with air in freezing conditions.
It's not the pressure, cause pvc is rated for more pressure than most compressors put out, it's once it does fail it fails catastrophically.
"Why do you hurt me when I do bad things to you?" My youngest son to his older brother
plumbbill,
actually that is true but what is also true is the temp of compressed air is capable of loosening glue joints..
200 -270 degree air temps have been recorded after compressing.. I've seen aircompressor exhaust pipes actaully glow under the right conditions..
If the system gets to 200 plus degrees the joints would be the least of my worries, since pvc's pressure rating drops considerably after 100 degrees.
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"Why do you hurt me when I do bad things to you?" My youngest son to his older brother
plumbbill,
I think that sort of temp is not usually reached by the average home shop unit. However feel the exhaust side of your compressor after it's been running for a while and you will know that temps get very elevated undercertain circumstances.
Please use caution, you can burn yourself.
Seems to me that you'd want 2 feet or so of some sort of flex pipe between the compressor and any permanent piping. And the flex should provide enough thermal isolation to prevent temperature-related problems in a home shop.
If your view never changes you're following the wrong leader
DanH,
Most home shops won't ever run compressors long enough to have issues with copper. but you are absolutely sure to solve the problem with a short length of flexible hose..
I have mine on a hose reel which holds 200 feet of hose,, I have another 100 feet should I want compressed air up on my roof to nail shingles on..
Good air hose, I use for a reference Goodyears 500 psi Grizzly has a max working temp of 190 deg. F.
So you are advocating use of rubber hose due to the high temp weakening solder?
Flex between the compressor and fixed shop lines is good practice for isolating vibration, the idea that tank outlet temps are going to soften solder is disproved by the fact that you are using rubber with a lower working temp.------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
Maybe a braided metal fitting such as this.....
View Image
Most of the large air compressors and refrigeration equipment I have seen use some sort of fitting like this to connect the equipment to the piping system.
As for temperature related problems you could always use a refrigerated drier to bring the air temp down.
Thanks for the warning.
I have worked on 800lb steam systems, & have installed 2, 85hp turbine compressors for Golden Grain Mission Macaroni.
"Why do you hurt me when I do bad things to you?" My youngest son to his older brother
Sorry Pumbbill,
I wasn't aware of your experiance..
Relax, I wasn't jumpin on ya.
I thought you knew my background----- I come from the heavy commercial/industrial end of plumbing, highrise condos are probably the lightest construction of my career.
"Why do you hurt me when I do bad things to you?" My youngest son to his older brother
Re: Your air lines in PEX, what max. PSI are you running them at? And, what brand PEX?
I'm about to install compressed air lines and had planned on going in type M copper because I can't find anywhere that the PEX people recoomend their product for air usage. If it ain't broke, don't fix it, just open it up to see how it works!
They don't recomend their piping for air---- they recomend testing with air in freezing conditions.
I'm using Uponor---- aka Wirsbo.
120lb standard home compressor type set up---- well sort of.
I'm buturing two old compressors & puting a single 5hp motor in between them.
"Why do you hurt me when I do bad things to you?" My youngest son to his older brother
"buturing"?
I worked on an industial job that couldn't pay. Ended up with many Grainger compressers with two cylinders each and the motor could be wired for 110v or 220v. Went 220. Welded up a frame to hold 2 compressers, replumbed them to use one pressure safety valve, one on/off switch, one gauge but ganged the tanks. After a ball valve I used a few feet of hose to go from a hosebarb output on compressors to another hosebarb on black pipe that goes around walls of shop. Various locations (benches, drill presses, sandblaster) have a "T" in main line and quick releases for hoses.
Originally thought I would figure a way for one 2 cylinder compresser to fill the paired tanks, then when additional air needed the opposite compressor (each has own motor) would compress the air so the first could cool down. Never did. 2 motors turn a total of 4 cylinders on demand. Together they take 1/2 the time to reach max pressure so compressor heat is not an issue with no complicated switching system. Can't believe what difference the ganged tanks made. I think they are only 20 gal each.
Son work on storage shed installation crew and they used a "pony" tank to achieve the same effect. Just hooked the quick disconnect on the extra tank into the manifold on the compressor.
PARTING SHOT:
Mechanic friend decided to replace compressor tank when it started rusting through from water condensed from air. Drilled a few holes in compressor mounting bracket leaving metal shavings. Habitually reached for hose to blow area clear. No air because compressor not on line for above work. My raucous guffaws echoed in the empty shop and were the only sound--until he caught me--and used me for a bellows. Tyr
Edited 12/23/2007 3:45 pm by Tyr
loucarabasi,
one cavot.. if you are running the compressor really hard, air temps can get over 200 degree or higher. as it reaches above that the solder can get soft and can weaken.. I've never heard of a blow out but I have seen a couple of joints near the hot end of the compressor weakened to the point where leaks occured.. They only occured in a shop using a big 15 hp compressor to run sandblasting equipment..
You'd have to hammer the heck out of the compressor though.. I doubt the average shop would ever have an issue..
The lowest temp solder melts at is around 360 F. I can't imagine any shop compressor ever causing an issue with the joints.
Tom
It doesn't need to get to the melting temp. motion and pressure help loosen it up.
Like I said it's rare and most shops will never operate with that sort of temps. But put a temp gauge on the hot end of a compressor that's been hammerin away on a hot day.. might shock you..
Only in Frenchys fantasy land would the tank heat up to the softening point of any solder used for plumbing. Maybe he heats his tank with a mapp gas torch while using air but I suspect it's just another example of Frenchy talking out his a$$.------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
dgreen
please do me a favor.. grab a hold of the air end of a compressor that has been operating on a hot humid day..
Do me a favor and grab the outlet of the tank where the shop lines would attach.
If the tank walls are reaching the softening point of solder you have worse problems than potential leakage.
Shop lines are not connected to the pump, they are connected to the tank.------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
Solder doesn't have to reach its melting point to fail. Prolonged operation at elevated temps, especially with vibration, will cause solder to crystalize and become very brittle.
If your view never changes you're following the wrong leader
All.............I have often wondered why people don'tuse regular rubber air hose' for permanant installation. Good Year has forty-eleven different grades for any application. Just idle thinking..............Merry Christmas....All
As I said to Frenchy, shop lines are connected to the tank. Is your tank going to reach the softening point of solder?------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
All the compressed air system's I have seen in Germany are done in Copper and the fittings are brazed to the pipes. This is used in Autobody Shops and some light industrial applications. The shops I've seen here in BC use black iron pipe or copper with soldered fittings. Nothing wrong with the soldered fittings in my opinion.Martin
MYHOMERENO,
There is a differance between brazing and soldering.. solder melts at a much lower temp.. and it's vastly inferior as far as strength goes..
Having said all that I'd say in 99% of all home shops would be fine using copper.. the sole exception would be big compressors used for continous sand blasting and I suspect you caould braze the first few joints where the heat is the highest and then it would be fine..
Lou,
As mentioned above, copper is OK....I posed this question here when a customer insisted on PVC ..." we had Sch 40 PVC in the last shop at 135psi no problem..why not here!!! Got lots of negative feed back with supporting links to "incident" reports (and OSHA info/regs IIRC) on explosions shrapnel etc.
I ran 3/4" copper, 3/4" drops c/w drip/dirt leg & drain on each with eared 90 deg threaded fitting with air coupler....wayyyyy more money (if you don't't have the copper "on-hand") but safer and much more user friendly than iron.
3 yrs later.....commercial shop...heavy use ... including paint and sand blasting.... no problem....
TN
In a former life, I sold the big compressors and helped set up systems. It would not kill you to isolate any piping with a flex hose. It is unwise to run compressed air lines in PVC. Many people do and it is a very bad idea--most get away with it but not all. Never saw copper in an industrial setting but it does not shatter like PVC could under certain conditions. I like the idea and would think about it in a personal shop.
What? No mention of CPVC? Seems like a way better choice to me. Of course I refuse to use PVC for anything except laying out symbols to aliens--the outer space kind. Tyr
PVC is great for laying out radiuses in visual...
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Many cpvc mnufaturers recommend against it. Here's one exmple
http://www.corzancpvc.com/designSpecInstallation/dosdonts.asp
I don't know of any that actually approve of it for compressed air.