Rigging rigid air compressor lines - what kind of pipe?

[DJJ]

I'm planning to set up my air compressor in a fixed location in my garage and run air pipe up along the wall, across the ceiling and down a foot or so, out near the middle. Anybody ever put together a system like this? If it matters, the compressor's a basic Crasftsman, 33 gallon, 150 max psi.

[garyk/nm]

Sched 40 PVC will do, but  galvanized line looks/holds up better.  Don't forget the water trap.

[DJJ]

I assume there are fittings readily available to mate pipe to the standard air tool couplers?

Where would the water traps go (low spot(s) naturally)? Are you talking about drains, like the one on the compressor tank, or something more?

I don't know too much about setting up an air system, as you can tell.

[Azrael256]

Poke around for info on water traps.  I have one that looks kinda like an oil filter.  You just drain it out when the system is not in use.  Most people I know just use the little glass or plastic jar looking traps on the compressor itself.  That's fine, but it should be augmented with one in the solid line.

I used PVC for my system, and it works just fine.  Galvanized would be nice, but it costs more.

Also, remember that airflow stops rust.  The system needs to be opened up on both ends when not in use to keep it dry.  If your compressor is staying in a nice dry garage, you should open it up whenever you're done using it.  Do beware, though, opening the valve quickly when the system is under high pressure can cause some unpleasant effects.

[garyk/nm]

Water traps, for example:
http://www.grainger.com/Grainger/searchcategory.jsp?category=%2FPneumatics+%26+Hydraulics
Good stuff at Grainger, but not the least expensive. Shopping around will pay dividends.

[cfabe]

No PVC, it can shatter. I'd use copper but in commercial settings iron pipe is always used. Tons of information on the shop-talk list at www.team.net

[K Frame]

No matter what kind of line you go with, spend a few extra bucks and install an in-line air dryer.

Nothing sucks worse than realizing that the expensive air tool you're using is spitting enough water to float a boat because there's no inline dryer and the water trap isn't keeping up.

[Wildalaska]

No PVC, it can shatter. I'd use copper but in commercial settings iron pipe is always used.

We run PVC no problem

WildalwaysissometimesAlaska

[kudu]

No PVC, it can shatter. I'd use copper but in commercial settings iron pipe is always used.

I run air piping almost every day.  PVC will shatter...  eventually.  On Commercial systems there is always oil vapor from the big compressors that will degrade PVC and cause it to rupture.  If the compressor's cut out pressure happens to stick and overpressures a PVC pipe system, it would be like a grenade going off with lethal shrapnel.  People have been killed because of this.  If the compressor is an oiless type PVC will withstand quite a lot of pressure, but PVC ages and degrades, after about 5-6 years I would not trust it's strength and would replace it.

Other alternatives include copper, black pipe, and galvanized pipe.  Low point drains should be included in the system and an air dryer if you can afford one, if not at least a good air filter that may catch some vapor.

I mostly install black pipe for air, copper for gases such as argon, nitrogen, helium,etc. and galvanized for sytems that do not want to get any rust particles in their sytems.  Stainless is also run in some clean enviroments.

If you decide to run PVC, I would recommend at least sch 80 thickness pipe.

[caseydog]

Hard piping for air serves two purposes , the first obvious one to get the air from point A to point B.The second less obvious but even more important to cool the air and condense out the moisture.

PVC is not good at all for the second purpose , very low transfer effeciency. Black iron is very good , lots of mass to absorb heat and it dissipates fairly well ,but it's a bear for the novice to install . Copper is a great compromise for homeowner type installations , put a water/oil seperator on the end of a 10 or 12 foot run of copper from the compressor and it will catch 5X the water that it does right at the compressor. I do a good bit of painting in a small garage and use copper and 2 seperators and a dessicant cartridge right at the gun, no moisture problems at all.

Ray

[DJJ]

Do you solder the copper, like you would on water supply lines? How do you join the copper pipe with the steel fittings?

[caseydog]

Yup , solder/sweat just like a water line , to adapt to the air fittings (which are standard pipe thread) you just need a "sweat to thread" adapter ,either male or female depending on what you're screwing in. The standard air fittings are mostly 1/4" NPT , so you need some reducers to adapt to the 1/2" copper pipe. You'll also need a short piece of hose to go from your compressor to the copper , don't direct connect compressor to any hardline or it'll shake it right off the wall. Home Depot has all the necessary stuff , but you may want to use a plumbing store for the free advice , the slightly higher prices can be worth the value of the advice.

Ray

[K Frame]

"Black iron is very good , lots of mass to absorb heat and it dissipates fairly well ,but it's a bear for the novice to install."

As a complete novice I installed several hundred feet of black iron piping for gas line during a home renovation. The inspector gave me high compliments for the quality of the job (obviously I was paying attention to EVERY little detail at that point).

The biggest pain in the butt is getting the threads adjusted so that your finish nipples are pointing the right direction!

If you're willing to practice on some pipe that you're willing to turn into scrap, it doesn't take long to get the hang of determining proper lengths and threading.

[TimH]

Ditto on the "don't use PVC" When it goes its like shrapnel (sp?) Here is a link to a discussion on this at another forum:

http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=1;t=009288

Do a search "PVC for air lines" over there and you'll get more negative input

I would probably go with copper since you don't have to worry about threading it.

[Leatherneck]

QUOTE: "Sched 40 PVC will do"

ACK! PVC under 120 psi is a bomb waiting to be detonated by a whack. It's also against code. Use cast iron pipe or high-grade copper, silver soldered preferably.

The big-box stores will thread black pipe for you, so you just have to design the lengths. My system has worked flawlessly for over 15 years now.

TC

[Bravo11]

We use PVC pipe in an industrial setting.  I'm not in maintenance nor do I spec out the air systems.  We have a 10 HP Sullair Screw and we run about 100 PSI constant.  I don't know the codes for this but the only problem I know of is when a fork truck mast hit a line.

[charby]

Black Iron..  

my 2 cents worth


Charby

[cfabe]

http://www.team.net/archive/shop-talk

They have literally beat this topic to death. The search function isn't great (read the directions) but there is tons and tons of information there.

[Brad Johnson]

On Commercial systems there is always oil vapor from the big compressors that will degrade PVC and cause it to rupture.

That's what dryers and oil seperators are for.

The maximum recommended working pressure for 1/2 inch (.840 o.d.) schedule 40 pvc piping is 600 psi. If it is installed in a relatively temp-stable environment (like a shop with some kind of nominal heatin and cooling) it should function fine for a long, long time. Plus, it's cheap and easy to repair if something does break.

I would not recommend PVC if it will be used where the working temps will be below 35 deg F. At that temp the pipe becomes brittle and can suffer physical damage from bumps and tugs that would otherwise be no problem. It's also a good idea to mount all the couplers on hard plates instead of just hanging them off the end of the pipe (having each coupler individually valved is not a bad idea, either). Finally, run a short piece of flex line between the compressor and the PVC piping to isolate vibration.

My brother has a first class setup in his shop. It's a v-twin compressor on a 300 gallon tank. Air dryer, oil seperator, and water trap - all of which get serviced regularly. All the couplers are plate-mounted and the sched 40 PVC feed line is soft-clamped into place inside the perling. Each connection is valved seperately, and there is a master shutoff valve at the tank. The system is regulated to 175 psi. The system has been in place more than a decade and he hasn't suffered any type of line failure.

Brad

[mfree]

The lines in my old garage were cast iron and *all over* the place. I think I had 6-8 outlets total in a 2 car garage. When dad put it together he was aiming to do paint work...

[DustinD]

If you really need dry air I would use a water trap followed by the filter that holds a roll of toilet paper followed by a desiccant such as silica gel. Silica gel can be recharged by putting it into an oven at about 400F.

An inline oiler can also help, but you may want to keep clean airlines around if you use your system to paint or do things that can not have oil contamination.

Another idea is to snake metal pipe back and forth to act as a heat exchanger to get water to condense. Put a drain at the lowest point and you will have a very dry setup.

[Sawdust]

Sweated copper in my shop; *never* PVC.

You can install a water filter, but I've found it easier and cheaper to just use in-line disposable filters that catch both oil and water. They work fine; I use my air supply mostly to spray fine finishes, so if I had anything get through the filter, I'd know immediately (fisheye, ya know).

Of course, running the piping with "u's" and ball valves catches most of the water and draining is easy.

HTh,

Sawdust