The Stovebolt Site Forums The Shop Area The Tool Chest Plumbing Opinions?

For the kind of plumbing that he air moves thru, that is.
So at my old house, and the one before that, which I lived
and worked at for about four decades, I had the basement and
garage plumbed in with ½” hard copper lines. Never had a
bit of trouble with it, and my thinking was that copper
conducts heat so well that it over its length it made a
good condenser to cool down the air before it gets to the
separator/regulator.
Now I’ve heard from a couple of people that believed the
soldered copper lines weren’t meant to take the pressure
than an air line might put on the joints and they can fail.
If you’re ever tried disassembling a properly soldered
copper line to save the fittings then I think you would
agree, that shop air pressure isn’t gonna blow the joints
apart. So I have no problem with copper for an air line.

Only one thing to say about PVC,……DON’T DO IT,
and that’s all there is to say about that!!!!!

Then there is the good old reliable black pipe airline that
TP Tools recommends/sells and that has been the standard
for a century or more in shops that require compressed
air. It’s cheap, it’s strong and although it’s not as good
as copper, it does do a fairly good job as a condenser. The
drawback to black pipe in my mind is it rusts and if you
don’t have a threading die it can be kind of inconvenient
for some people. Some say to use galvanized then some say no
,it will flake and clog filters, I haven’t found that to
be true at any shop that I’ve worked in and many places have
had a mix of black and galvanized, which ever was handy late
on a Saturday night when you needed to run a new line somewhere.

I’ll bet everyone has an opinion about this, so let’s hear
what you think and why you think it.

Denny Graham
Sandwich, IL

Denny, I love the question. We can discuss this for months. My answer, subject to change at any given time, is black iron pipe. I plumbed my compressor in with black iron, much like TP Tools recommends, 10 years ago. I have not had a problem. I recently decided to extend the coverage and added about 30' of both 3/4" and 1/2" black iron pipe. I have mixed galvanized fittings on occasion without concern or notice. I think copper would probably work but have some concerns about the thickness of the walls of the pipe. Rust, inside the pipes I guess is the long term question. The outside of the pipes is a non-issue. I live in the desert and for the most part we don't allow much rust. I'm betting I won't live long enough to see my pipes rust out from the inside but we'll see.

Geo

What you need to start with is what is the max pressure of your system? Single stage compressor 125 psi? 175? 2 stage. Pipe all has aworking pressure and burst pressure. As an example there is type k and l copper, steel schedule 40 or 80. Lines should be sloped etc.

And don't forget the burst pressure of the filter/regulators. If it has a "non-steel" read this as "plastic" bowl, it's probably rated at 125 lbs. many compressors, mine included will cycle automatically between 145 and 175 lbs. some of the regulators with plastic cups have metal straps around them to catch the big pieces of shrapnel when they blow. Problem is I'm afraid of the little pieces too.

My installation: black pipe and following the design guidelines given by TP Tools. I bought all-brass valves from Harbor Freight.

http://www.tptools.com/tech-metal-piping.dlp

I do not have the threading tools. I bought threaded lengths and got it done very quickly. I have had no problem in over 12 years. I have never had moisture in the "feed" lines but I drain the drops a few times every summer (and, before winter hibernation).

I used black pipe when I did my garage. A couple of friends of mine used PEX to plumb the compressed air in their shop. They've never had a problem with it & it was light years easier to run & work with than black pipe.

Thanks guys, but I'm not looking for recommendations, I
already know what and how I'm installing my plumbing based
on past 50 years experience.
Things have been real dead around the bolt lately and I just
thought I stir things up and see if I could get one of those,
mine is better than your's discussions goin'.

From the Engineering Toolbox: working pressure of sch40
wrought steel pipe is 1300psi GW, and burst is 10,380psi.
Don't know why one would even consider sch80 at 1750psi with
a burst of 14,000psi, unless they were planning on running
steam to the spray booth.
Even Type 'M' drawn copper has an internal working pressure
of 850psi and burst of 6185psi. Weak spot is the solder joint,
which I don't have the time tonight to look up but I'm sure
it's well within the safety range.
Don't think my Speedair two stage compressor is gonna come
close to any of those, so that's not a concern.

Harbor Freight isn't carrying the ball valves any more Tim,
checked just today as I was looking for some 1/2" ball valves
to use as drains and for valving off different legs.
I do have a set of threading dies, bought them when the
plumber quoted me $1,200 to pipe in the Natural Gas to my
furnace. Hunert bucks for pipe and seventy more for the die
set, I did it myself and had some new tools for the tool box.

Slope the pipe down hill???? Of course, the first lesson that
any plumber learns is that sh!t runs down hill.

I gotta move the compressor to the other end of the building
eventually. Think I'm gonna add an electric drain to it then.

dg

Second lesson: hot on left and cold on right.

OK, since you are wanting to have an argument, we slope the black iron lines "up hill". Condensed water all runs back to near the compressors where it is drained from a vertical receiver tank. We have had this system for 20+ years but do not have a down hill system to compare. It seems to work OK.

Mar-Ktech

Mar-K, here it comes. You have a "down" system it just depends on which side of it your standing Sorry, I couldn't resist.

Put in galvanized 10 years ago and have not had any problems. I keep it drained and have a water separator. So far so good.

On the other hand my nephew and I ran PVC in his shop 10 years ago and he's had no problems. However, just for "some" safety, we ran it overhead in the ceiling and came down the way with steel pipe.

Just my contribution today!

Ya beat me to that one Alvin, you young guys are just to quick
for me, and you're up past my bed time also. See, you're
talkin' relativity now, it's all relative to where you are
standing in space.

PVC is rated at around 300psi, but like a soap bubble, a blow
from a hammer or bump it with a falling something and it can
burst. Bad stuff to run compressed air thru.

I may have miss understood what was posted earlier, but I
though mention was made about corrosion in copper pipes. I've
seen copper water pipes that were in homes for thirty years
and the inside looked as good as it did the day they put them
in. The exposed lead on the other hand does tend to oxidize
over time.

I'm running black iron on the pipe that's outside the walls or
ceiling and I'll run copper where it's gonna be up in a joist
space or in an enclosed wall.

I've seen rubber hose permanently installed in the attic or
walls to get from one end of a building to the other. Bad idea
in my opinion, unless it's just used as a temporary deal for
a single job. In my mind flexible hose should only be used as
the terminal point in an air system and kept as short as possible.

I would love to have a dryer at the compressor. I had given
some thought to several different ways to accomplish that.
A coil of copper, a series of switchbacks of copper, a
refrigerant heat exchanger if I could find one large enough
that would take the pressure. When I was working in QC
running CMM's we had refrigerated dryers that supplied our
machines with bone dry air, big bucks though and out of the
reach of the average Joe like me, and a bit of over kill for
an auto hobby shop.

dg

More than 10 years ago, I bought one of these (50% off - free shipping back then). We do not often get high humidity, but I turn it on when we are painting.

Boy oh boy, is there nothing that Harbor Freight doesn't try to
make a copy of. I'd like to see one with the cover odd, to see
just what they are doing.
Hope it works good, cuz I'll bet when you move down to the coast
you're gonna need that.

dg

I had copper in a previous shop. Changed to galvanized about 10 yrs ago with a change in shops. Have never seen any flakes in the filters. Had occasion to rearrange some piping about 5 yrs ago. What I took apart was clean on the inside.

I've been in several chemical plants around the world. Many of them used galvanized for their instrument air lines (though most have converted to electronic instruments now).

I saved a heat pump condenser once and started to make an in-line cooler but gave up when it looked like it was more trouble than what it was worth to do all the plumbing needed to make it work well. Ended up selling it for scrap

The pressure ratings on most PVC pipe is based on an ASTM specification that is for liquid service only.

Still doing air brake line with push connect fittings. No problems so far.

I also had a large heavy copper heat exchanger with 1/2" lines
from an industrial refrigeration unit. I dragged it around
for thirty years and scrapped it after I made my move a few
years ago. Wish I'd of kept it, I would have put it to work
now. That's exactly why I try my damnedest not to throw
anything away. It never fails, the day after I scrap
something, that's just when I'll find a use for it.

I've also thought about running a coil inside of a small
refrigerator but by the time you get it all together you could
have bought one already made. That one that Tim posted starts
looking pretty good when you think about making your own cooler.
I'm starting to feel like a Deve. Think I'll come back down to
earth and get practical. For as much as I'm going to use the
air in a hobby shop, that piping arrangement that TP Tools
suggests is more than adequate.

dg

My genetic make-up (the laziness gene) guides me to the KISS solution. My black pipe run (50 feet lateral run), meets my simple-minded criteria:
- cheap but safe/strong
- installable by me (with a few good pipe/monkey wrenches)
- long run from an isolated room aids water elimination
- compressor a good distance away from work area
- no moisture problems
- impresses my friends (looks good and makes sense for moisture elimination).
- a rise/drop (and output connections) at 4 joints (KISS).

The shop/garage in the house we are buying in NC has a pressure-rated plastic-line system (modern muscle car enthusiast). That set-up scares me.

When it comes to pvc I have personal experience.
I built a filter out of 4" fittings and it wound up as shattered shards of s#&t on the far side of the garage.
On the other hand I run 1\2" pvc from the compressor to my new filter/distribution manifold and have had no trouble at all.
My lesson was that large pipe=large surface area and more psi/square in.
That said, my 1/2" pvc still runs Outside the house/garage up against the soffat where if it were to let go it would do no harm.

On a side note I use a small Aluminium heater core as a condenser before my entry point... so the idea that radiators can't handle any pressure past 15 or 20psi is BS.
JMO

DG,
You have to watch out when reading Deve's posts. It rubs off on you.
I'm thinking he would have come up with geo-thermal, which I oppose, as it would directly heat the planet and melt the glaciers.
Carl

Yeah, don't do things MY way.. then I wouldn't be UNIQUE. Please keep our planet stable and don't try to upset the balance of things! LOL!

The TP Tools diagram is a very good method. Mar-Ktech has a good plan there too. The biggest thing to remember is that compressors put out HOT air. It takes this HOT air about 25 feet to cool enough to cause condensation. So any water trap that you put prior to this 25 feet is wasted. This is just a fact that I learned during painting. I figured I would just come right out of the compressor with a 25 foot hose and start painting. WRONG.
You add 25 feet of pipe, even if it means doing a switchback, watertrap, and THEN you put your 25/50 foot rubber hose for painting.

I have helped a few of our local manufacturers really enhance their water trapping because of this. Its important.

I ran black pipe in the garage i had in California... then used a hose out of the compressor for the next 9 years! I never got around to hooking the compressor to the black pipe.

Black pipe is strong, and a PITA to cut and thread. It will not take any kind of shifting or vibration. Copper is more forgiving and easy to work(cut and join) and more forgiving if shifted or vibrated. Copper comes in M(residential hard pipe), L(commercial hard pipe), and K(used by utility), there is a L soft as well. used often under ground to accommodate some shifting if need be. This might be helpful: http://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf
Page 21 through 29 will give the working pressure, burst pressure and includes the solder joint ratings as well.