Did some poking around over at Breaktime where this has been discussed quite a bit. I’m about to ‘plumb’ my new air compressor and will be using black iron pipe. No PVC to be sure. Copper would probably be easier but I do have pipe tools and some experience with cutting and threading pipe so decided I’d go for broke with the BI.
I understand the issue of possible corrsosion inside and will be installing all piping to grade away from the compressor (main trunk line above the rafters) with a terminal drop with ball cock drain. Drops to the workspace will be teed *up*ward then elbowed down to the QD fittings teed off horizontally from the drop and elbowed *up* with the drop continuing below the tee to another drain cock. Compressor will be isolated from the hard pipe with a short section of air hose to prevent transimission of vibrations from the compressor to the piping. Water/oil separator located at the main outlet from the compressor to dry the air before it gets into the ‘system’.
Have I forgotten anything?
From Beautiful Skagit Co. Wa.
Dennis
Replies
I'd put a quick disconnect on the hose between the compressor and the piping if the compressor is at all portable. That way, it would still be portable to take to your brother's house, the jobsite, etc.
I completed most of the air system with black iron installed the way you're doing yours, but wanted one more line to the back of the garage for sandblasting outside. It had so many angles and turns that I put it off for years. Last month, I needed it and got frustrated. I "plumbed" it with a good quality hose attached to the ceiling and beams with conduit clamps with a quick disconnect by the back door. It works, and it'll out last me!
Telemike -Considering it took three of us to unload the compressor from the truck I don't look at it as portable (grin)...Good idea about an outside connection. Maybe a couple.Thanks.Oh - is there anything relative to freeze protection with outdoor air outlets that might be a concern? We don't get *lots* of freezing temps here but once in a while. I suspect as long as I keep those lines well drained they should be OK............
From Beautiful Skagit Co. Wa.
Dennis
If you're going to be using a lot of air, it might make sense to add a cooler.
Why arn't you going with galvanised pipe? That seems to be the material of choice here
Jako -Galvanized? Dunno .... just whenever anyone speaks of iron pipe for air it seems to always be black iron. Is galvanized pipe galvanized inside, too? Never looked (grin). I suppose if it were it would forestall the corrosion business............
From Beautiful Skagit Co. Wa.
Dennis
Dennis
It's impossible to think of everything so in hindsight I would have allowed a little more flexiblity in making changes to my system.
I have found that it is almost an annual ritual (during our Christmas shut down) to change some aspect of the system. One year we moved the compressor to the other end of the workshop because it had developed bad manners & would fire up in the middle of a conversation with a client & usually scare the daylights out of them.
I think that the original choice of copper & (flaired fittings rather than brazed) has worked for me because I can relatively easily add or move a line or a fitting as required. I know you mentioned you have the gear to do the same with iron pipe but its one disadvantage is that you usually have to disassemble a few fittings to get to the one you want. Maybe the use of the odd compression fitting which may allow changes without undoing a whole lot of fittings would make some sense.
Don
Thanks everyone for contributing to this discussion.Since this is not a prof. shop, just my safety net to preserve my sanity in old age, flexibility and change isn't a huge issue. With respect to future revisions or additions I'll be sure to install a number of plugged Tee's here and there 'just in case'. Copper would indeed be easier to install but me personally I just have a mind set on using black iron pipe. I think if the shop ever caught fire I'd be far less concerned about a fitting coming unsoldered than I would just getting the hell out of the place but it is a point probably few give thought to.Thanks again for chiming in............
From Beautiful Skagit Co. Wa.
Dennis
The folklore is that galvanized is subject to shedding little zinc flakes that you don't want on your sanded surfaces, in your tools and finishes, etc. Same reason not to use galvanized in gas pipes, don't want flakes in your gas valves, burners, etc.
Good point about the zinc flakes but gas is relatively dry and compressed air usually contains moisture unless run through a dryer.Even gas pipe has dirt pockets to collect rust particles.One is probably as good as the other .We also have moisture traps ,filters and pressure regulator at the drops as our lines are 50-60+ feet from the compressor
I'm surprised that no one has mentioned using high density polyethylene piping. It goes together with push to connect "O" ring fittings, it's safe for gasses, and it's good to 140psi, and you can cut it to fit with a knife. I also doesn't rust.I just got finished putting a three stage, 3Ø, air compressor in my shop, and I was planning on using HDPE.Tom
tms -For whatever reason most references I've found don't recommend using plastic pipe for air. The HDPE pipe you're talking about sounds like some kind of high pressure flexible tubing (???) Some mention has been made in other places I've looked about high pressure tubing but in most cases it's been judged too expensive for 'casual' use such as a home shop.Dunno ... I do know that I asked my heating contractor if the left over PEX tubing would be suitable for air in the shop and he gave it an emphatic thumbs down!...........
From Beautiful Skagit Co. Wa.
Dennis
Hi Dennis,HDPE itself is not very expensive, but the fittings are. All in all, once you consider the labor envolved in the installation, the cost is comparable with other materials.The real advantage comes when you want to add, or otherwise modify the system. You can just cut the tubing and plug in the additional fittings.I use HDPE for air systems at work, and usually get the supplies from either Ryan Herco, or Harrington Plastics.Tom
It sounds like the HDPE tubing you mention is rated for use with compressed air. Is it something readily available?
The big concern is when people use rigid PVC pipe, which is definitely NOT rated for use with compressed air.
http://www.tptools.com/statictext/airline-piping-diagram.pdf
They recommend black pipe, as you intend to use. Although I'm using thick-wall copper on mine. I disagree with their "safety hazard" comment about soldered joints. If they are done properly, and you use lead-free solder (which is rated to higher pressures than leaded) they should be able to handle the pressure.
In any case, the imprtant thing is to run the air through long lengths of metal pipe, to cool the air and make the water vapor condenseout, so the water separators can do their job.
Exactly! And give the pipe a bit of pitch to drain back down to your drain. I plan to run my pipe next to the basement concrete wall to keep it nice and cool.
To my mind, the safety risk of copper is not that the joints can't handle the pressure, but that in a fire the solder will melt, the pipe will open, and large quantities of compressed air will fan the fire.
You are correct. the fire hazard is something to think about, for someplace like a auto garage or engine repair shop. There should not be any problem using copper pipe. Although I would also put a auto drain and a dryer on your system.
Copper is easier to work with than black pipe That's IF you can use a torch,and not set the building in fire.;-)You can never over clean copper,the cleaner the better,and use a good flux.( I like tining flux personly)
I've installed both type of piping systems at my work.
"O" at work we needed to use silversolder. but our piping is used for medical air , You are not planning on using the air for breathing air? I hope??? ;-) (if you are there are a hole set of guidelines.)
Have a happy new year
C.A.G.C.A.G.
my issue with copper is that a sodered joint is a potential failure point. heat happens when you compress air and that heat will reduce the strength of a sodered joint.
A pipe fitting buddy of mine would never let an apprentice soder the hot water pipes, in his opinion if a joint were to fail it is most likely to be found with hot water than cold.. the water in pipes is a lot cooler than the compressed air.
The hard part of my arguement is that you haven't had a failure and you clearly are invested in your approach.
Unless I was willing to pay to replace your pipes my self maybe I should just shut up..
but since this forum is about sharing ideas in my opinon (and that's worth exactly what you had to pay to get it) compressed air should only be in either black iron or the flexible hose rated for it..
Hello Frenchy
Na everyone has there own opinons on how things should be done. truthfully, there are always a number of ways to do almost any job, that are correct. Ive never had a problem with soldering copper lines, As Ive said Ive done it a number of times.After saying that I do perfer to silversolder copper lines (old navy habbits die hard. The U.S. navy dose not use anything except silversolder, beacuse of the reasion of fire melting the solder joints.)
copper is a good corductor of both heat and cold. on the air conpressors that Ive use lead free solder on, the lines realy dont get that hot,(Not like hot water.) Presure is a biger problem,as I see it. but for low psi units(under 100psi).I use an expanstion joint or a hose off the conpressor to stop vibration from possibly damageing any joints.
I always remove the factory drain, and replace it with eather an auto drain, or a ball valve that is easy to get to. for draining the water out of the system.
Your objections have been noted. Thanks, but I agree to disagree about your conserns. If someone knows how to make a good solder joint I dont see any problems.
P.S. at schools the way thay test a solder joint is to cut the fitting in half and see if and where the joint breaks ,when being forced apart. a good solder joint should fill the hole fitting, not just the top,(called caping ).Again Its all in the knowing of what and how to do something that counts! ;-)
Take care Frenchy.C.A.G.
I dunno. I've worked for Fortune 500's that were so safety paranoid that they wouldn't let you bring Elmer's glue from home (no MSDS on file, after all). But they used copper for air piping in the labs.
Every joint is a failure point. But it's pretty easy for an experienced person to make a good solder joint, and easy to tell when you've made a cold joint. And you need to use the right solder.
I also think runs should be sloped downward along the direction of airflow, so condensed water does not need to work "against the flow" to get to a drain.
Copper pipe is suitable for hot water at 100psi.I suspect that compessor air is not as hot and that pressures above 100psi are not needed. If so copper is suitable.
I think you guys are being gnit-pickers. Six years ago I ran a 1/2 inch copper pipe (from a 60-gallon C-H compressor) with soldered joints across my shop, up and down, with two dryers and two quick-connect fittings and I've never had a problem. Never think about it.
Uncle
You could well be right about solder, I have no soldered joints, most are flair & nut with a couple of brazed fittings, however I think the flexible air lines would go bang long before a soldered joint let go.
I was talking to my local panel shop proprietor who has just relocated & installed high density poly mainly because he had long runs & relatively few outlets. It was approved by Workcover (who are well known nitpickers). Their only requirement was to paint them blue, he tells me that it is on the toit list with a low priority until they give him a better reason 'than they might be mistaken for water pipes'.
Don
dloc briefly mentioned this and since it sounds like you're setting up a one-man home shop it probably won't make any difference for you but if you wanted to give it the deluxe treatment you could run the system in a loop. this is usually done where there's more than one person/machine drawing air to equalize pressure- basically it means nobody/no drop ends up 'first in line' on the pipe and therefore can't hog the air from those downstream.
m
Mitch -Yeah, a loop system would be the cat's meow but this cat has rather limited kitty litter to sprinkle around. (grin) I'll have to make do with a single line system. Or, when I win the lottery I can add the loop. (hehe)...........
From Beautiful Skagit Co. Wa.
Dennis
I'd suggest a valve before your hose section at the compressor, so you can isolate/depressurize the manifold without emptying the tank...
do you have a block heater on the compressor?
David -Don't understand - "block heater". Are you thinking this is a gas powered compressor? It's electric.Shut-off between the main line and compressor is a good idea. Thanks. Hadn't considere it but will include it now!...........
From Beautiful Skagit Co. Wa.
Dennis
compressor block heater for cold weather operation - - compressors start/run hard when cold - in our midwestern climate a larger compressor in an unheated space should have a thermostatic controlled heater to keep the oil warm...may not be necessary for you - sounds like your climate is quite a bit milder...
"there's enough for everyone"
I cut and threaded too many pipes as a plumbers helper. I have had my air on a copper plumbed system for 5 years with no problems. One thing I added was a drain valve in the line close to the compressor and main shutoff valve. This valve allows me to blow out any condensation in the line at its lowest point and is handy for quickly dumping air. Good Luck in whatever way you go.
Cheers,
Greg
Greg -Most of the replies in this thread have implied that the main line(s) are sloped away from the compressor. My thought is if there's a trap or condensate drain at the compressor like something you describe perhaps it would be better to grade the lines towards the compressor instead. Condensation would, I should think be more probably nearer the compressor than further away??Of course, drains at each drop are required as well............
From Beautiful Skagit Co. Wa.
Dennis
If you plumb the drops by pointing the "T" fitting upward you shouldn't need drains on each drop. By pointing the "T"s up it means the water will stay in the main pipe. Also by pitching the main lines back to the compressor it simplifies the process of draining the water from the tank. Basically you only need one auto drain in the system or if doing it yourself it means draining in one spot only. It's a piece of cake for the small shop air system. I've been in the industry for 35 years and have seen huge buildings where every mistake in piping was made. Why don't folks consult tech experts at compressor companies? The answers are already out there and have been for years and yet folks try to reinvent the wheel everyday on the web. I find more misinformation on the web than real documented answers. I have a nice little booklet by Ingersol Rand that gives all the basics for piping and it's really quite simple.
You hit the nail on the head on condensation in my opinion. I sloped my main towards my trap at the compressor. My main exits the compressor 90's down, unions onto a flexible copper tube which terminates to another 90 to turn horizontal. The line then has a tee with the vertical feeding the overhead main and the remaining tee leg has a short nipple with a ball drain valve. So I have a nice little trap right where the hot air hits cold pipe. I was concerned about vibration causing failures so I mounted my compressor on rubber pads on a box on more rubber pads, the compressor shows very little movement and I still have no leaks. Just a couple of thoughts. Have fun!
Cheers,
Greg
Greg -For the flexible copper coupling between the compressor and the main line did you use the kind of copper pipe they use to connect domestic hot water heaters? I figured I'd just get a short piece of air hose made up and use that but considering I'm trying to build the "dream system" (grin) using a 3/4" flexible copper water heater connection pipe would allow more air flow(??)Since my compressor is an upright that's hugely top heavy I poured a small slab about 8" thick, drilled holes for anchor bolts that were set in hydraulic cement and left to cure for a week before any stress was put on them. It's really rock solid!...........
From Beautiful Skagit Co. Wa.
Dennis
I bought a short length of 3/4" flexible hydraulic hose from Northern Tool. It's rated at 2500 psi, so I figure it should be OK.
As I suggested earlier, I use HDPE tubing for most of my airline installations at work. My second choice is black iron because when I use copper for gases (even air), it has to be "L grade" hard wall pipe. The expensive "blue labled" stuff. That's code here.Tom
I've been 'lurking' on this question, and I still haven't seen anybody mention something I'm familiar with. I worked in auto garages and also for a compressor service company. What we always used to prevent uneven pressure in the piping is a loop system.
In the last install I was involved with the loop ran all around the shop overhead and the whole assembly was tilted toward a corner where the drain was. All taps in the system used drip legs with drain cocks as well as the usual filters, seperators and regulators. Even though the compressor was never going to be used as a portable, a shut off and QD was used just for service and safety considerations.
By the way, I have no experience with galvy pipe. Never saw it in a compressed air system. Dunno why.
Regards,
dhb
Put ball valves on each of your drops. They are cheap since you don't need full flow valves. Connectors eventually leak. Buy two brass automatic drain valves from Harbor Freight that are designed to drain water (by venting a little bit of air) from the tank everytime it starts up. Put one on your tank and one on your separator. If you have more than one person using air at the same time, you may want to consider a loop pipe. Last but not least, run a big line to the patio so you can hook up a steam whistle (from the local antique market). It is a great way to call the kids home or impress the grandkids.
A good web site for copper piping and application is the copper development association web site, their web site is http://www.copper.org
Just to throw this in... I used to work as an instrument tech in a refinery. Many instruments were pneumatic (100s) and required clean dry air. We used black pipe every where. This was an outdoor corrosive nasty wet environment and there were no problems. We used SS tubing to the the instrument or valve.
TF -Stainless steel air piping ... NOW we're talking! (hehehe)...........
From Beautiful Skagit Co. Wa.
Dennis
All I can say is how thrilled I am that I know how to use a hammer.
Please tell us you're running a production cabinet shop and that this isn't for your backyard studio.
Edited 1/5/2005 4:48 pm ET by BossCrunk
> ....Please tell us you're running a production cabinet shop and that this isn't for your backyard studio.I do a lot of airbrush work. ...........
From Beautiful Skagit Co. Wa.
Dennis
You could use Schedule 80 PVC. At 73 Celcius it has a safe operating pressure of 370 PSI. That is for 3" though. 1/2" and 3/4" is a higher pressure I believe. It is fire resistant (like firegard drywall) and verey easy to work with. I imagine that you will only be using 120 PSI or so in your compressor, so the rating would be sufficient. YOu can buy all the neccisary male and female adt. that will allow you to install your quick couplers as well.
Just a thought
Derek
PVC, even schedule 80 PVC, is too brittle for use with air, and it gets more brittle with age. When it fails under pressure it fails explosively, that is, with flying shrapnel moving fast enough to cause injuries. And it can burn through. See earlier posts in this thread about failed air pipes fanning the flames.
Just to add to what Uncle Dunc said,Any oil making it's way from the compressor to the pipe will draw the plasticizer from the PVC, and it will get brittle in short order. That's why you don' t use pipe dope or cutting oil on PVC threaded pipe.No reputable pipe merchant will sell you PVC for compressed gasses. It 'aint code, and it 'aint safe. Don't do it. Besides, Schd 80 PVC is expensive compared to all the approved alternatives.Tom
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