What's the consensus for plumbing a commercial shop?

Copper? Galvanized? Black Iron? What are the pros and cons? Any advice?

PVC is a no-go, by the way (OSHA). (chair)

Scott

Our shop has a plastic similar to PVC that is OSHA approved. Not sure what it's called, but it's blue.

All copper here....

:cheers:

If you want to do it to "code" then you must use an L or M hardness of copper tube. Not the stuff you get at Home Depot that is used for water, you can find it at a plumbing supply house. You have to use a silver bearing brazing rod on all the joints. To get things up to the temp. that silver braze will flow you will need an acetylene/ air torch.

Mine is black iron, but be sure you have some sort of filter at your outlet. After a few years, you will get some rusting in the lines. Where I work, it was so bad that it plugged up a regulator. Put a small filter on it and it filled it up in about a minute!

Copper won't rust and it might even give you a little cooling on the way.

As for galvanized, I haven't found a good use for it yet. If the galvenizing doesn't flake off, it will still rust after time especially at the joints.

my .02

http://www.ipexinc.com/Content/EN_CA/2_0_Products/2_1_Industrial/2_1_4_Compressed_air.asp

The approval letter.
http://torque1st.clubfte.com/OSHA_PVC_Pipe.htm

I would go with copper.

As Bubba indicated, copper will give off the heat of the compressed air, although I am not sure if this matters for what the air is being used for (tool, etc.).
PVC is out mainly because compressed air can easily exceed 200F and the temperature limit of PVC is 140F. It will turn to spaghetti if exposed to temperatures above 140F. CPVC is out also, it can handle 180F maximum.
Doing a little browsing on the web it appears that ANSI/ASME (B31.8) limit the use of PVC, or other thermoplastics, for transporting compressed gases.

The blue stuff refered to by Gerry may be polypropylene, not 100% sure. Even this has a temperature limit that isn't much more than 200F.

Soldering the copper should be just fine unless you plan on very high pressures. You may want to refer to a temp-pressure chart that will indicate what the limit is for soldered copper fittings. I have one filed away somewhere. Soldered copper should be good for 125 PSI at least.

If you braze the copper fittings you will be golden, since this will handle pretty much any pressure that a compressed air system can throw at it.
Copper type M, L should be just fine. Since compressed air will not corrode or errode the interior wall, M will do just fine. L buys you some extra wall thickness that isn't really needed for air applications, unless of course you will be banging things into the copper tube, then the extra wall thickness will be a little more resilient to being bent or crushed.
In all the Lab projects I have been involved with (day job) type L copper is what we specify. I am not sure what copper tubing 2muchstuff is refering to. The tubing at Home Depot should be the same as a supply house for water or air, but I could be wrong. I know there is ARI rated refrigerant copper tubing, but that is the only other copper tubing I know of.
The other benefit of copper with brazed or soldered joints, over threaded steel, is that these joints are easier to make air tight.

Just my $0.02.
Chris

That's it. The Duraplus is what we have.

Just a for what it is worth.
Type K copper is the thickest walled and is what is put in concrete floors for residential water lines.
L is next and M is the thinnest.
I am not fond of M, after working with the other two it seems flimsy; it is primarily what Lowes and Home Depot sell though sometimes they have L as well.
They are frequently mixed up in the store's racks...
Check for the color code: K is green, L is blue and M is red; the inspector sure will.

Oh yes, and I use black pipe, it can take a serious bump, but yeah, like Bubba said, it rusts.

That Duraplus is rated at 185 PSI at 73F. What is the pressure rating of the pipe at 200F? The air leaving the compressor when you compress the air to 100 PSI or better is going to be hot.
Did they use the Duraplus on the distribution only, and used something else close to the source?

Sorry there Dieguy, you already had the link attached would referenced the ANSI/ASME standard. I should have looked at your links first.

Chris

As for galvanized, I haven't found a good use for it yet.

LOL

The truth and the whole truth so help me experience :D

I have seen the blue plastic stuff installed in a plant in Canada and I know it is OSHA and locally accepted, but it looks expensive for some reason....and I have only heard or seen it used maybe two times in the last three years, so I am a bit sceptical. If it was the greatest thing, it would be used more frequently, don't you think? There has to be a reason or two it's not more popular.

Any rough comparisons in price and ease of installation when compared to, say, copper?

Scott

That Duraplus is rated at 185 PSI at 73F. What is the pressure rating of the pipe at 200F? The air leaving the compressor when you compress the air to 100 PSI or better is going to be hot.
Did they use the Duraplus on the distribution only, and used something else close to the source?

Chris

We have a 50HP( I think) screw compressor that runs around 180°. From there it's a ~2" steel pipe to the drier, then into a ~150 gallon tank. The Duraplus starts at the tank. We have several hundred feet of Duraplus, for about 8 years now, and have never had a problem with it.

I have seen the blue plastic stuff installed in a plant in Canada and I know it is OSHA and locally accepted, but it looks expensive for some reason....and I have only heard or seen it used maybe two times in the last three years, so I am a bit sceptical. If it was the greatest thing, it would be used more frequently, don't you think? There has to be a reason or two it's not more popular.

Any rough comparisons in price and ease of installation when compared to, say, copper?

Scott

It goes together just like regular PVC pipe. Very quick and easy. Not sure what the cost was. We bought and had it installed with the compressor as a complete system.

Something that size and type (50 hp screw compressor) typically have inner coolers and aftercoolers to remove some of the heat from the stages of compression. Some of the less expensive recips, especially the compressors the hobbiest have, will not have coolers. If you are using a refrigerant dryer that will remove some more heat. Then the receiver of course removes even more.

It has been a long time since my last design of a compressed air system. 17 years ago or so. It was a Ingersol-rand centrifugal compressor. We used a steam regenerative air dryer with two chambers. One chamber active while the other regenerated. Problem on this design was that there wasn't enough time between the regenerative cycle and the switching over to the other chamber. The dessicant didn't have enough time to cool off which caused the air to come off the dryer very hot, until it removed all the heat from the dessicant. The air was still hot leaving the receiver for that short period of time. In hindsight there should of been a cooldown cycle utilizing the plants chilled water. That's what you get for relying on manufacture sales reps.
Hope no one minds the short story.

Regards,
Chris

I am leaning towards using copper.

SO - I have another question - my tie in will be close to a shared compressor. I do not expect to use all that much air - mainly for die grinders and blow guns but I want dry air and the compressor is located under a canopy - OUTSIDE.

Do any of you have ideas or plans on how to construct an efficient method for extracting the moisture - a home-brew? If you suggest getting a commercial dryer I will hunt you down and give you a wedgee. I promise. I have incurred so many unforeseen expenses with this shop I am expensed out and have nearly diminished all of my 'extra' funds already.

The inlet to this 'dryer' will be 3/4". I plan to exit the dryer with a 3/4" trunk, go vertical 16' then branch into 1/2" drops distributed throughout the shop. The trunk line will be 16' up in the ceiling and the taps will come down the walls. I plan to pull the air from the top of the trunk line using kind of a J arrangement and the trunk line will be off plumb to collect the moisture at the end of the line. Drip legs will be at each connection point, of course. Am I missing anything? All input is greatly appreciated.

As I said - my volume will not be all that great but with the compressor located outside, I am concerned that when I pick up a die grinder I am going to have a line full of moisture. Oh - I am in Virginia - where the humidity is above 90% most of the year.

Thanks!

Scott

OH - this compressor does have coolers between the stages on both pumps. It is a relatively small (120 gallon?) two stage, multiple pump, piston compressor, Chris. I do not have the specs. It's fairly new, too - maybe 5-8 years old? - not sure.

Thanks!

Scott

I would go with copper.

extra wall thickness will be a little more resilient to being bent or crushed.
In all the Lab projects I have been involved with (day job) type L copper is what we specify. Just my $0.02.
Chris

you are right, the l or m is wall thickness and you can either and home depot. don't bother silver soldering it, it is so easy to get a good soft solder joint, the temps don't demand ss and you could probably prove that the copper would burst before the soft solder sheared over those 1/2" joints.

How's this for over the top paranoid…. when I did my shop in copper I did it in about 4 big assemblies with the final put together done using compression fittings. Why? I thought about all the acidic flux that’s going to be sitting in the lines waiting to get inside of air tools, a steam engine run on air, paint, etc, and installed it this way so that I could flush out the flux with hose before compression fitting it all together!

They have the standard inline particulate and coelescent filters, if my memory serves me right. The coelesent filter will remove some moister. I don't remember what dewpoint it will give you. Certainly no where near -40F DB. You have to open a valve regularly to drain the captured moister. I don't think you will mind doing this routinely. Some is better than none until you can find a used refrigerant or dessicant dryer out there somewhere.

A compressor outside or inside doesn't matter unless your shop is air conditioned, then inside has a slight advabtage.

Chris

Spelled coalescent wrong.

Here is a company, "Pneumatic Products", that make high efficiency coalescers: coalescent filters (http://www.pneumaticproducts.com/P_2000.htm)

These will remove both water and oil aerosols. I don't think it lowers the dewpoint of the air though, just removes very small droplets of water and oil.

Chris

Hello Mextras,

First let me give a bit of background. I am in the sign and graphix business. We do alot of spray painting so we have to have very dry air. I also paint cars in my spare time.

Now to your problem. I don't know how big your shop is but all the research that I found when doing my system said that it takes 50' of 3/4" line to cool the air down enough for your collectors to be of any use. So what I did was to use copper for the first 20' of my air supply line with this length running uphill at about 1/4" p/ft. This is were I put my first drop leg. I then changed to PVC and continued at the same pitch for another 20' and put my first outlet with a tee out the top of the pipe about 12" tall. This outlet is fine for using dust blowers and general tire inflation, NO TOOLS.
Then I went another 20' to the spray booth running downhill the same pitch as before to another drop leg. After the drop leg I "tee-d" into the pipe again and put 3 moisture filters inline, about a foot apart. from ther on no more filters no more drop legs till the end of the run, about 70'. Once a week I drain the drop legs. just before painting I drain the compressor and the filters. absolute dry air like living in Pheonix or Death Valley. Hope this helps. :drowning:

Jimmy Southern

PS I know I should not use pvc but this was a trial run to see how dry it would be. I am going to run all copper this fall. :banana:

Mxtras PLEASE READ ENTIRE POST!!

Now that the groveling is out of the way, I am going to make one more suggestion. If you do not have enough room for the system I mentioned in the previous post, then try this idea. Yes it is a dryer but should be a very cheap one.

Go to your local Heating & air installer and see if they have a small house AC condenser unit that has a bad compressor (this is the outer unit in the AC system). If they have one get it for as cheap as you can. Also try to find one that the fan on the top still works. Now go home and set it up beside your compressor. you will have to either braze or use compression fittings to attach it to the compressor. This should give you more than enough cooling to get the water to condense out of the lines.

Most of these are 220 volts so you should be able to use the same power supply for the upper fan on the unit. I would get a 220 relay and set it up to come on when the compressor does. Then put in your line filters for the moisture as before. Be sure to make a way to drain the coils entirely for the winter months or come spring you will have a heck of an air leak.

So don't come hunting, I'm just the messenger.
Jimmy Southern:)

Now go home and set it up beside your compressor. you will have to either braze or use compression fittings to attach it to the compressor. This should give you more than enough cooling to get the water to condense out of the lines.

Please Jimmy tells us more. What are you connecting to the AC condensing unit? Do you mean that you are using the condensing coil on that unit to circulate the compressed air through where the condensing unit fan is drawing air across the coil? or is the compressor on the AC condensing unit still functional and you are somehow utilizing that refrigeration circuit to do some cooling?

Chris

Hi Chris,

The Coil is purely to get the air enough surface area to cool down without having to go aroud the shop 5 times before the first outlet. The only original parts that are used is the cooling fan and the coil itself. If the 220 relay is still in it I would probably use it also.

Good Luck
Jimmy Southern

I came in on this discussion about dry air a bit late but have a little addition. Run a line from the drop legs where your condensed water collects to the blow gun on your machine. That way whenever you blow off chips and stuff you drain the drop legs. A little bit of moisture out the blow gun doesn't hurt as much as forgetting to drain your system regularly enough.

Everyone has given good information and ideas. Thanks for all of the input. I am going to run copper and I will likely build my own condensor system to extract moisture.

I will hopefully be plumbing things in a week or two - I finally got the clearance to move in to the building...so as soon as I sober up from the party I am going to get to work. (Just kidding - I don't drink)

Thanks again - any other last minute ideas or suggestions?

Scott

Hello everyone,

I was at my local heating and air place Friday and asked the guy that does their service work about what he thought about the outer unit idea. He said he had never thought about it but that it should work quite well. He had one suggestion. He said you should first degrease the coil hose because in most of the units you will get given to you the compressor has died. Usually the oil from the compressor ends up coating the inside pretty thoroughly. This oil would decrease the efficiency of the heat transfer. The oil that is used comes clean pretty easily with a good degreaser. He recommended using a couple of cans of brake cleaner sprayed in the top of the coil and let gravity run it the rest of the way down then rinse clean.

The other recommendation I have is to make your own coil. If you have a wood lathe this should be easy. Make three identical dies with half round grooves in them and make up a simple ring roller. I'm sure if anyone can build a CNC machine you have the skills to make the roller.

Hope this helps. Just remember cool air means dry air. :drowning:

..... Thanks again - any other last minute ideas or suggestions? .....

Scott

Not related to compressed air; having run my own operation for 25 years I suspect a person has to have air between their ears to start out. You will start feeling that at about the end of the first month and every month after that. Don't worry eventually you learn to ignore it.

Good luck

Jimmy, don't use PVC for air lines. It is not rated for compressed gas and is illegal in most places. It is very dangerous to use. Check with your local codes department. Even the manufacturers will tell you not to use PVC for compressed air. If you have already installed it get rid of it and install iron pipe. Apparently even copper is not allowed in some areas due to fire codes.

I guess I never noticed, but I don't recall the air from my compressor tank being noticeably warm. I do drain the tank every month or so, but not much moisture there. I have a 60gal tank. Of course, I don't use it that heavily most of the time, so the air has plenty of opportunity to cool off. Maybe that's why.

Just a thought.

Dave

The main tank is the primary air cooler and moisture condenser/trap on most small shop systems. It should stay at near ambient temperature unless air is being used heavily.

As mentioned, the compressor will be outside under a roof, so it will be at ambient temperature, for sure! Cold weather might be an issue.

I am planning to put an automatic drain on the tank, for sure.

Scott