I’m setting up a new shop, and want to hard pipe my compressor to several drops through out the shop. I’ve considered black pipe and copper, I’ve ruled out PVC, and pondered PEX. I was wondering if anyone had a preference for ease of installation, and durability. Oh yeah, please keep in mind I’m a furniture maker, and not much of a plumber.
Thanks,
Dave T
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Replies
Copper is the easiest - Plastic is a definite no.
Joe H
I have always used galvanized pipe because of moisture in the lines. Be sure and slope the lines so water can be let out of a drain easily.
I'm not sure if copper will stand the pressure, I've never seen it used in body shops.
You get out of life what you put into it......minus taxes.
Marv
Most type L copper will stand at least 200# of preasure.
Well, in retrospect to my prior comments, I'll add this...
Galvanized is great for ease of modification, but prone to minor leaks on a high PSI (175) system. A properly done copper system (type L or K) is better in that soldered joints don't "wheeze" air, but adding or modifying to it in the future can be a pain. If you start adding in unions all over the place, then they can leak too.
If I had to do it all over again, I'd go with copper in my shop, and a really well thought out plan.
The sound of my 7.5HP two stage kicking in at 2:00am has gotten old, and really pisses off my wife, which seems to happen at least twice a week.
Jon
I run alot of air in my shop, it more mainly as a mechanic shop the woodworking. welding, cutting, sand blasting engine repair, truck in and out. I do not need pvc lines that will get bump or copper that will get dented. Galvinize has been known to leak. I run three 240v compressor and most turn off at 250 psi. I will only run black iron. I,m nty going cheap on my safety. who ever first thought of pvc as air lines need their but kick. it was never design for pressure.
who ever first thought of pvc as air lines need their but kick. it was never design for pressure."
Brownbagg,
That is true, but what exacerbates the problem is despite the pressure rating on the side, a compressed air system can see temperature fluctuations that are extreme enough to make it brittle or soft, plus the joints seem to fail most often. But like you said, it has absolutely no place in a compressed air distribution system.
Jon
For ease of installation, copper's the best bet for a non-plumber. I wouldn't risk PEX personally, because the oil from your compressor may attack it over time. That said, miles and miles of non-crosslinked PE tubing are used for small-bore industrial air lines, so you might get away with it. We use PE and nylon tubing all the time for 1/4" OD air feeder lines- but I get a little scared of it beyond 1/2" OD. Remember that unlike water, there's a tremendous amount of energy stored in compressed gas, even at a mere 100 psig- a failure can hurt people...PVC's not an option because when it fails it generates damaging schrapnel.
Copper's durable against corrosion from condensate, but not (nearly!) as durable against damage as black pipe. It's way easier to work with than black pipe- no need for unions to permit leaking joints to be re-tightened, and soldered joints seldom develop leaks later if they're tight to begin with. Make sure you use the proper plumbing tubing, not the DWV grade (drainage, waste and ventilation) and support it properly. I'd also isolate the compressor itself from the rigidly-mounted air line using a piece of air hose to prevent vibration from being transferred- it will reduce the tendency for the line to fatigue and break over time. Make this hose and the line itself big enough in diameter so that you don't choke off your supply. If you've got a compressor of 5 hp or less and you're not expecting to use more than two drops at the same time, 3/4" tubing should be good enough unless you've got a very large shop. You can get away with 1/2" if you'll never use more than one drop at a time, and if you mount your pressure regulator at the point of use rather than at the tank.
Mount each of your air drops securely to your structure so that there's less chance that you damage or kink the copper if somebody trips over a hose. There are some nice sweat-solder elbows with ears on them for mounting to studs etc. And make sure you install a drain leg with a drain cock on the line (and empty it periodically) to prevent any condensate from ending up in your tools. A coalescing filter's a good idea too, though it alone sometimes won't be enough to completely eliminate condensation in the lines.
Hope this helps-
With galv or black pipe, you can put it together with a wrench (two, actually) and take it apart later if you want to reconfigure. A couple of decent wrenches will be maybe $50 total. You can figure out the pipe lengths you need and get them cut and threaded and the hardware store or spend another $125 on a Ridgid threading ratchet and die. Threaded pipe is fairly easy to do. Aside from wrenches and threading you need a bit of teflon tape or pipe dope, and a vise to hold the pipe. Chances of a leaky joint are minimal. Cutting into the middle of an iron pipe line is a chore and worth avoiding. If you're really slick you might incorporate a left/right nipple and coupling here and there to let you break in later if you need to.
With copper, you spend maybe $25 on the stuff you need (torch, ignitor, flux, solder, abrasive cloth, fitting brush) and learn to sweat pipe. It's not hard to do, just read up a bit in a how-to book from the home center. Copper fittings can be disassembled if you want to reconfigure, but it's a pain and worth avoiding. Chances of a leaky joint are minimal but higher when you first start sweating copper (or, like me, after you first get an acetylene torch and don't realize how hot it is and how easy it is to burn all the flux out). If you want to cut into the middle of a copper line, it's easy. And, copper is cool looking stuff and basically fun to work with.
I guess they sound about the same, huh? I did both last week and they are both somewhat time consuming but almost foolproof if you have mechanical skill. Maybe it comes down to what the material costs, which I don't have a good handle on.
All this said, I would go with PVC because it's SO easy and will do what you need. Only tools required are a small saw and a measuring tape.
Don't run pipe so that there are low spots to trap moisture, and don't forget to put drop legs in your lines to the outlets. That way the moisture in the lines descends to the outlets and is removed from the lines as you use air. It's not a bad idea to put a blow gun at the end of the system. Obviously the concern about moisture is greatest if you use black pipe.
I probably won't be the first, but let me say;
DO NOT USE PVC PIPE ON COMPRESSED AIR
There are one or two types of ABS pipe suitable for compressed air, but they are specialized. There are types of flexible plastic hose suitable for compressed air. But under no circumstances should you use rigid pvc pipe for air. It can blow up, and when it does, it is a shrapnel bomb.
Right on!
I would only consider using PVC if the pressure would never be allowed to exceed 90 psi, and the temperature was always kept in the human comfort zone, and even then, only schedule 80 PVC, which isn't particularly cheap. I've seen the shrapnel from a scedule 40 PVC airline failure. Nobody was injured, but only because they were lucky. One piece penetrated 1/2" sheetrock.
All in all, copper, iron or high quality air hose are your best bets.
Dave
Hmmm.... I know of one system in place made of PVC, the thick-wall variety. It's in a large production plant and runs at 125 PSI. Maybe they make sure to stand well away from the lines at all times..?
I would guess that it never gets really cold or hot in that plant while the air pressure is up. PVC gets brittle when cold, and soft when hot... I'd stay well clear. I've seen too many stupid and dangerous installations in industrial settings to assume that because it's in a plant, it must be OK.
I believe there are some non-metallic pipe materials that will hold up to temperature extremes and high pressure, but the ones I've seen are neither cheap nor readily available.
BTW, the failed PVC system that I saw had been in place with no apparent problems for 3 or 4 years. I suspect that the failure may have been due to accumulated deterioration caused by a combination of factors - pressure pulsations, mechanical vibration, thermal cycling, contamination with compressor oil, and who knows what else.
In any case, I'd recommend sticking with the old reliable materials. I don't think the cost savings of PVC offset the risks.
Dave
You are right! Loss of eyes does not help your cost!
i'm in the process of doing the same thing and i'm going with copper. if we were in an area with lower humidity i'd go with black iron (i've heard galvanized can flake off tiny chips that get in your tools) but i don't want to spend the money on a big drier. i mostly just use it for blowing out chips and sawdust anyway- rarely run airtools. i have the tools and experience to run iron or copper, so that wasn't a factor in my case. i've read the mass of iron does a better job of condensing out the water than the relatively thin-walled copper, but i don't think it's that critical for my application.
running air lines is not done quite the same as standard water plumbing. there are ways to configure it to minimize water getting to the tools. it mostly involves putting 4"-6" risers up off of the tees on the mainline(s) instead of dropping straight down, then teeing horizontally off the drops so there's a 6" or so trap below the tool junction tee with a drain valve. no riser or tool connections at the end of a run- just a drain. there should be a "soft" connection (hose with permanent fittings) between the AC and the plumbing to isolate vibration and of course, all pipe should slope away from the compressor about 1/8" per ft. 3/4" lines (or bigger, i suppose) are recommended for all but the lowest volume applications.
i've got a diagram from some company that shows all this, but the numbnuts didn't put any contact info on any of the 4 pgs. they actually sell the components for setting all this stuff up, but it's all stuff you can get at any hardware store or plumbing supply (home depot/lowes, too, obviously).
since my walls and ceiling are still open, i'm thinking about hiding some of it. maybe using threaded fittings wherever the pipe will drop down thru the ceiling or come out of the walls so A) the drops won't need rocked around- i can drill holes and screw them together after the drywall is up; and B) if we ever move, i can unscrew and take the whole drop assembly with all of the expensive ball valves, connectors, etc. with me. the new owner can supply his own if he wants air. also this method would be easier to hang the pipe on the joists and studs, instead of needing to suspend them with some sort of bracket to allow for the risers. it would look a lot cleaner and since i'm only working with a 9' ceiling, there would be less stuff hanging down in the way.
have fun!
m
Are you sure it's PVC? There are applications using ABS for air. I think the companies that make air rated plastic pipe have agreed to make the pipe and fittings green, so that it is immediately apparent that it is the ok stuff. ChemAire is one brand, IIRC. But for all that, I think black iron pipe is the way to go.
To all
I'm also piping my shop this winter.
I plan to use all black iron pipe, as I already have alot of it, and fitting, adapters, etc.
I do have a small question:
I was wondering if the standard variety ball valve from the Harware store is ok, or should I go for the more expensive specialty valves from the supply house.
PSI is about 175 max, probably more like 125.
Piping will be no more the 60ft max, 3/4 ", galvanized elbows.
Did the same thing years ago in my old shop, so I have alot of material except the valves.
Can't seem to remember what I used then (20 yrs ago.)
Jeff
I have a ball valve for my main shut off, can't remember where I got, probably work, but it clearly says "200psi max" on the body, so read what they say at the hardware store and go from there. The worst that will happen is it will leak, it won't explode.
Thank you,
I guess that makes my life easier.
jeff
I would go with el-cheapo. Most of them are rated for 125 pounds. but I have jacked them up to 150 pounds (Code requirement) with no problems. Keep your recieipts.
The pipe in question is white, installed in a large cabinet shop with stationary machinery that uses compressed air (and vacuum), in California without a cold winter or particularly hot summer. The compressor is an enormous rotary vane unit with a big dryer downline. There is an area with drops for air hoses for hand tools used in assembly, but I do not remember what the piping is there. Certainly this cannot constitute much of an endorsement of whatever pipe that is, because there's no guarantee that the plant engineer has any brains, but I think it's PVC and I worked adjacent to the shop for a few years and never knew of a problem. After reading the other posts here I would definitely stick with copper, because the rust/flake issue is about zero.
If you know the damage that PVC can cause on air lines why would you recomend it? ! Bogus,Bogus, Bogus!
Your advice on air lines is close to being correct. But one caveat; under no circumstances use regular PVC for an air line. Under air pressure it has the potential to explode like a hand grenade. Live long and prosper!
Where I work they used copper for all the high pressure air lines.
If you have a very long run, it can help to put a holding tank down near the far end, especially for things like nailers that take short bursts from the system. That way you're less affected by the friction in a long run of pipe.
Make a list of the air tools you use or plan to get, and their pressure and volume requirements. Based on that info, you might want to design in local regulators and gauges.... It can save time over going back to the compressor and messing with the regulator all the time.
-- J.S.
I use 1/2" black pipe for main runs and 3/8" for branches. You need a decent amount of volume for most tools, and it's easier to build the setup bigger now than find out you've built it too tight when the pressure at the tool drops by 20psi in use.
Use a water separator/filter at the compressor outlet and build a couple of dead tails into the branches with plugs or valves for draining. If you think you'll EVER have any kind of paint gun use, do NOT use an in-line oiler.
Mike
Back when I bought my first nail gun, I was primarily making furniture. I didn't want the noise of the compressor in my shop (but the miter saw is ok!) so I put it in the garage, as far away as possible. I plumbed the whole shebang using 3/4" copper, with three drops in the garage and three in the shop with the ability to expand, if necessary. I wired it with 220v and put switches in the shop and garage. The switches are low voltage, which energizes a relay, which kicks the compressor in the pants when I want air. I used a hydraulic hose off the compressor to the main line and included filters, regulators, etc at the compressor discharge.
If you've never sweated copper before, it is no sweat. Running the copper lines will give you some practice on a system where integrity isn't 100% mandatory, as it is with water.
Another detail I incorporated was to remove the compressor drain petcock and using fittings and threaded pipe, brought it out to where I don't have to get on my hands and knees to drain the tank (and replaced the petcock with a 3/8" ball valve.)
Good luck.
One detail you might consider if you have a large shop or there is a posibility of more than one person using air is this: Install a loop system with a slightly smaller id pipe than the main pipe coming off the compresor. That way each access point in your system is getting make up air from two dirrections eliminating presure drops regardless of were you are hooked up to the system.
Kitec is approved for air lines. It is fast, flexible, stiff enough to stay where you put it, and you need no joints except at the tee's and the terminations.
Kitec is a PEX-AL-PEX product.
Guess that answers the question if PEX is OK as a material. (Not saying the tubing is OK, just saying the material is OK.)
I work as a mechanical engineer in a manufacturing plant. Do not under any circumstances use PVC, CPVC, or any other plastic pipe for any compressed gas. The only exceptions are that 1/4" flexible plastic tubing is ok, hoses made for compressed air, and a specialized rigid polymer pipe made specifically for compressed air. The pipe is not made in standard sizes, so it cannot be intermixed with standard plastic components.
As others have said, when plastic pipe fails under pressure from a gas, it fails explosively and produces shards. This does not happen when filled with liquids. In addition, plastics are attacked by many solvents, so plastic pipe can fail well below it's rated pressure for water, and can certainly fail if you whack it. Your air compressor will introduce some amount of solvent into the compressed air, not only from tramp components in the lubricant, but in the ambient air supplying the compressor. For example, paint fumes from the shop. Acetone is particularly harmful to PVC.
On another topic, I don't believe anyone has mentioned, but make sure you have a way to drain moisture from your system regularly, and don't let moisture in the drain accumulate and freeze.
I can say from experience that PVC is a no-no for compressed air. I worked in a shop in 1981 that had an 11 hp air compressor pumping air thru 1" PVC lines. We had four drops (two hard hosed for nail guns and two for air hose connections) and one day right after lunch with everyone at the bench, the main line let go at a Tee joint. The Tee joint exploded hitting two people, a ten foot length of pipe after the elbow broke the clamps that held it to the wall and 150 psi of air created such a dust storm that we could hardly see the roll up door to get out of the building.
The entire system was replaced with black iron pipe.
Thanks for sharing that. I've heard lots of people warning against PVC because it can or might explode, but you're the first person who's seen it happen. Having an eyewitness makes the danger a little more real.
"I've considered black pipe and copper,"
Dave,
FWW did an article on that not to long ago, #162 (My comments are in FWW #164). Good article. FWIW, IMO, all lines (except the isolation line off the compressor) should be min. 3/4" GALVANIZED (not black pipe), should always slope away from the compressor, and should have multiple down stream drains and vertical takeoffs.
As stated before, PVC and CPVC have no place in compressed air distribution systems, PERIOD.
By following this route, and having long enough supply line (at least 50' to 100'), the distribution system will act as a large condensing coil, drying the air, and eliminating the need for any kind of a drier.
Jon
Edited 11/10/2003 9:40:47 PM ET by WorkshopJon
In my opinion, threaded pipe's fine if you own a threading machine, but there's no question that copper is way easier for an amateur to work with. I wouldn't want to have to run to the hardware store every time I needed to shorten a nipple...Copper's also cleaner and resists condensate corrosion better. If your primary concern is resistance to mechanical damage rather than ease of installation, forget copper and go with rigid threaded pipe.
As far as valves are concerned, stick with ball valves. The cheapo Nibco threaded valves at HD etc. are fine, but make sure the valve you're using is rated for at least 150# WOG (water, oil, gas service). Brass/bronze valves and copper are a good combination- less good with galvanized or black pipe, because the brass/steel connections will result in galvanic corrosion if the pipe gets wet with condensate inside or outside. If your air is dry and your shop is heated continuously in winter, feel free to use the brass valves even with black pipe- corrosion will probably take a long time. Just make sure you have a filter at your point of use to catch any rust or debris and keep it out of your tools (you can skip this if you use copper IMHO).
If the others haven't hammered this point home enough, NEVER use rigid plastic pipe for compressed air. Small-bore air lines can use commercial polyethylene, nylon or polyurethane tubing, or hoses designed and rated for use with compressed air, but the rigid plastic pipe/fitting options are limited to a few manufacturers- and should only be used where the risk of external corrosion to metal piping is the primary concern. Commercial PVC, CPVC and ABS are NOT designed for compressed air use, and can injure or kill people when they inevitably fail. The pipe can look just fine for years, then explode without warning. If you ever see PVC in pressurized gas service, make sure you report it- you could be saving someone's life, or eyes...
The only plastic pipe sutable (that I know of) for compressed air service is an ABS product by ChemAire. http://www.nibco.com/chemtrol/chemaire/ChemAire.shtml
Liberal Arts Graduate
Will Think for Food
Thought you might find this helpful.
It's from an article (Let There Be Air) in the Dec 2002 issue of Woodshop News. Just looked and the article is no longer available on-line.
Dave
I,m a plumber and we install air lines on a lot of shops we are working on. We have also replaced PVC airlines on shops after they have exploded. We usually install copper lines on the shops with all lines exposed for future changes, compressor attached to hard piping with a flexible high pressure hose, main line graded away from the boiler with a drain at the end of each branch, all drops (tees) to come off the top of the main line and then turn 180 degrees and go down with a drain on the bottom of each drop below the air connection, another idea we he have used on a few buildings that are tight for room is having the steel posts used to support the beams and or I-beams for rolling hoists capped off and have pipe-o-lets welded in so we can use the posts as air storage tanks thru out the building we cap off the bottom first and pour an epoxy in to seal the bottom to lesson the chance of rusting, we put a drain on the bottom of these also that should be drained at the end of the workday along with all the other drains.
I have seen automatic drain valves for compressors. How well do these work? I assume the same thing could be used on drops, or can it?
Yup. Grangers and Ace Hydraulic carry them.
With one on your tank, an inline water seperator and sediment traps w/ a petcocks on your drops why would you want to spend all that money for automatic drains. A 3/8 WOG ball valve is cheap.
Who ever invented work didn't know how to fish....
I would definitely recommend copper. Use type L tubing, sweat it with plenty of flux (GoodCrest self-cleaning type will make your life easier) and plenty of heat, and you shouldn't have any trouble. ½" should be fine for your application.
Using nipples with frame ears for mounting your chucks is a good idea, as someone else mentioned. Obviously, you should use teflon tape at all threaded connections.
Use ball-valves for all cut offs. Get the threaded models and take the trouble to sweat threaded nipples into the lines, with unions where necessary to make sure you can unbolt things when needed. Sweating ball valves into a line takes a bit more practice than just tees and elbows; also I've found the components inside the valve don't like too much heat.
Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
Dave,
Here is an interesting alternative. It is slightly more expensive initially, mainly the fittings, but very easy to put up and modify as needed. I am getting ready to plumb our entire shop with it. I looked at the product at a recent trade show and it looks pretty trick.
http://www.garage-pak.com/
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
That Garage Pak was shown on Shadetree Mechanic a few years ago. Similar to the conpression plumbing lines that are becoming available in the US. These have been used for years in Europe and the marine industry but plumbers have been pretty slow to accept them, if they have at all. One other thing, PVC was never designed for pressure? Is water not under pressure? If air gets into the plumbing, does it hammer when turned off? The hammering is pretty hard on all piping, not just PVC. I don't want to be near PVC when an air line blows, expecially when the brass fitting shoots across the room but when it happened at work once, it got our attention. The company told us to use it and we did. I won't use it again. Drains and lower pressure stuff, OK but not high pressure.
"I cut this piece four times and it's still too short."
One of the problems with pvc is that the higher the temps, the lower the pressure rating. Compressed air is hot coming out of the compressor.
That's right. It seems logical that the PVC line used most would be the first to fail from fatigue. At least in my mind. I'm not sure why the line at work broke that time, it was rarely used and the shop didn't get below about 65 degrees. Someone may have yanked on the hose to break it off, though. Not as if anyone would admit they broke it. Like I said, I wouldn't use PVC again for air. I have pipe on what I installed so far and will be adding a hose reel in the middle of the garage soon.
"I cut this piece four times and it's still too short."