Replies

1. 
   WayneL5 | Dec 28, 2003 05:48pm | #1

   Yes, copper is fine.  Never, ever use plastic pipe for compressed air.

1. 
   alanplanesaw | Dec 31, 2003 12:37am | #18

   You said not to use plastic.  Why not? 

   3/4 inch, schedule 40 is rated to something like 200 or 300 psi?  If I am only running about 125 periodically, why not.  I put plastic in my relatively small shop after seeing several others who have used it.  I recall even seeing it mentioned in articles.  The only danger I read about was if it was struck while under high pressure.

   Any info would be appreciated.

   Thanks,

   Alan - planesaw

1. 
   Tao | Dec 31, 2003 01:14am | #21

   >>You said not to use plastic.  Why not? 

   Because of practical experience.  Schedule 40 pipe is rated for cold water only, not hot air and vibraton from compressed air, and it does fail spectacularly way too often when it is used for air lines.

   Case in point: many years ago, I tried to save a little time and money when re-routing the air lines in my plant.  We used Schedule 40 pipe between some existing sections of galvanized pipe, because I didn't want to take the time to cut and thread galvanized.  ALL the plastic pipe failed within a few months, and loudly.  Fortunately nobody got hurt.  Line pressure was only 120 PSI,and the pipe was ten feet off the ground.  It didn't fail at the joints, the pipe just blew out in chunks. Loudly.  It happened in August, when ambient temperatures were highest.

   I think galvanized pipe is the recommended carrier for air.  Copper would be my second choice.  Black iron is used for gas pipe because of the way gas reacts with zinc, but it does rust way too much for air pipe.  It's good to route your pipe to drain, but every drop leg should have a water separator and regulator, and a leg below the regulator with a drain valve.

   As far as pipe size goes, 1/2" is plenty for a one person shop for runs up to 100 feet or so, I'm sure, especially if you mount a regulator near where you are working.   I often paint using up to 100 feet of 3/8" hose, and half inch has about 80% more capacity than 3/8".  2" was more than adequate for a 60 person shop with lots of machines that used air, as well as three spray booths.

   Michael R.

1. 
   alanplanesaw | Dec 31, 2003 02:42am | #25

   Thanks.  I generally try to separate fact from fiction, identify Ford vs Chevy, and myth from reality.   My 3/4 inch sched 40 PVC pipe run totals maybe 35 to 40 ft.  It runs at about 100 to 110 psi.   A small shop of about 18 x 20.   I have two drops each with about a 10' coil of hose. 

   For this short of a run (40 ft.) I could probably just switch to flexible hose.  The PVC is so much easier to install than copper or black or galvanized pipe.   My compressor is oil-less from HD so I don't worry about oil in the pipe.   Water/condensation is not much of a problem in winter (Pennsylvania), but I have to drain the tank and line more often in summer.

   Thanks again for you info.  Will have to consider whether or not to switch to something different.

   Alan - planesaw

1. 
   Sphere | Dec 31, 2003 04:10am | #28

   Well suprise..the guitar shop was in coopersburg pa...we ran 3/4 copper..mains, lots of 1/2 drops and all the drops had the point up tee ..every drop that went to a fixed machine had an isolation flex (hose) and a ball valve drain aft. drops to bench space had a quick connect and drain (again ball valve) ...for what you describe...seems that hose is fine..I have 300' that I ran to build a goat shanty...2 framing nail guns at once..then a coilnailer to my neighbors roof..all worked fine. But these posts are good to understand the nuts and bolts of it..be safe and happy in the long run..

2. 
   alanplanesaw | Dec 31, 2003 04:55am | #31

   I'm near Hershey.  Have a friend who owns a construction company (CC Inc.) who lives in Coopersburg.  What kind of "guitar shop?"

   Just curious.  Alan - planesaw

3. 
   Sphere | Dec 31, 2003 05:24am | #32

   Well, my brother (1/2 actually) went to Milton Hershey...graduated in'73. I spent  alot of time there visiting.

   The Guitar company in C'burg, was PBC Guitar Technology. We built the American version of Ibanez..as well as our own. I was the production engineer there for 5 yrs. I was also head of the 'Custom Shop' where individuals had us construct an instrument to thier liking..PBC is no longer but one of the owners and patent holders is still going...http://www.bunker-guitars.com/tf_neck.htmlwe have made thousands of guitars and some for very accomplished players.

   I had also worked with Michael Dresdner when we were involved with http://www.kensmithbasses.com/...and had a blast with him and our experiments with http://www.acc-net.com/hydrocote/hydrocot.htm...

   check it out and hope that Hershey is still the same..Duane

2. 
   JohnWW | Dec 31, 2003 01:32am | #22

   Alan,

   1. A pipe at 125 PSI is easily at a high enough pressure to throw shrapnel at dangerous velocities if it shattered or a fitting snapped off and turned into a missle.  To the uninitiated, air under pressure seems relatively benign, but at 125 PSI it is capable of doing serious injury if you happen to be in the wrong place at the wrong time when something lets go.  If you were ten feet away when a pipe shattered you would only be startled, but if the pipe were running up the wall and just a foot way from your face when something let go you'd be badly hurt.

   2.  The plastics used to make water pipe become progressively more brittle, and the safe working pressure drops, when the plastic is exposed to oils and solvents.  If you are using an oil lubricated compressor, oil will quickly contaminate the inside of the entire pipe system and start working at the chemistry of the plastic.  Air piping is also exposed to heat and vibration levels that were not considered when the pipe was rated for water pressure safety.

   3.  Over a period of just a few years in an active shop, the chance that the piping will be struck with a blow that might cause shattering is almost certain.

   There are safe alternatives that don't cost much more than plastic water piping, why take the chance?

   John W.

1. 
   alanplanesaw | Dec 31, 2003 02:45am | #26

   John,

   As you can see in my reply to Woodwiz, I may decide to consider something else.  Maybe just a long hose.  The pvc is so easy to install compared to metal -- for me anyway.  Don't have pipe cutter or threader. 

   Thanks for giving me some facts to consider.

   Alan - planesaw

1. 
   rslatm | Dec 31, 2003 03:24am | #27

   http://www.osha-slc.gov/dts/hib/hib_data/hib19880520.html

   OSHA guidelines on PVC

   Remember Type K or L not M for copper.

   Black pipe is what most large places use.

   Auto drains are available at Grainger, mcmaster.com or look in your local yellow pages under compressors.

   For piping info go here...

   http://www.tptools.com/statictext/tech_notes.asp?mscssid=7P0K1JD0MNXF9LTTU8MKRAFBCU0FFHGA

   Then click on...

   Air Line Hookup - Metal Piping Diagram

2. 
   Tao | Dec 31, 2003 04:24am | #29

   Good info.

   The hot setup these days is aluminum pipe with push-on fittings, but it's way expensive.

   Copper pipe is smooth for less line loss, doesn't corrode in the presence of water, and is relatively cheap and easy to install and modify.  Solder will melt at rlatively low temperature; silver solder has a higher melting point, brazing even higher.

   Black iron is cheap but labor intensive to install.

   Galvanized is  little more expensive, just as much a pain to install, but has better corrosion resistance.

   There are plastics approved for compressed air piping, but they seem to be more expensive than copper or iron, and they melt easy, if that's a concern.

   They all work.

   Michael R

3. 
   alanplanesaw | Dec 31, 2003 04:41am | #30

   Thanks Rick.  I followed your links and came up with several others that fully support what you and others have said.  Following is a good explanation with bottom line -- don't use PVC for compressed air. 

   http://www.team.net/html_arc/mgs/199702/msg00437.html

   One thing I was pleased to find is that there is an ABS pipe made specifically for compressed air that can be joined/connected like pvc.  Don't know what the cost comparison is, but will be checking that out.

   Thanks again,

   Alan - planesaw

3. 
   grousemouse | Dec 31, 2003 07:38pm | #34

   Alan,

   I have another reason that has not been mentioned for not using PVC.  I used plastic and had the run near the ceiling so it would not damaged by impact.  I had a hose connected at one of the drops and gave a slight, and I mean slight, tug on the hose.  It was enough to flex the pipe slightly and the 90 degree joint at the ceiling burst under the combination of 110 psi +/-  abd the slight flex.  Scared the hell out of me.  The plastic may be able to withstand 300 psi in an ideal world but with the addition of any additional stresses that number obviously drops dramatically.  Needless to say, no more plastic for me.

   Brian

1. 
   alanplanesaw | Dec 31, 2003 09:09pm | #35

   Had breakfast with an industrial friend and he agreed with everyone here -- no pvc for compressed air.  Am looking for Duraplus, which is ABS for compressed air systems. OSHA approved.  Although I don't have to deal with OSHA, I do take them as an indicator of what is probably safe, or at least what I should be concerned about.

   Thanks,

   Alan - planesaw

1. 
   rslatm | Dec 31, 2003 10:28pm | #37

   http://www.ips-plastics.com/comp%

   http://www.gwspipe.com/linesheet.htm 

   http://www.fpweb.com/archive/June_99_piping.html

   http://www.ipexinc.com/Content/en_ca/index.asp

   Duraplus is one of many ABS plastic makers.

   http://www.ecompressedair.com/library/piping.shtml

2. 
   PlaneWood | Dec 28, 2003 05:57pm | #2

   If you plan on staying under 150 lbs pressure then I'd use the thick wall 1/2" plumbing copper tubing (available at HD).  It comes in 8' (10' ?) sticks.  Or, use refrigerant tubing.  It will have a bursting strength of over 300 lbs pressure.

   The moisture in compressed air will cause black pipe to rust on the inside, with time.  The debris will then tend to clog up your line valves.  A moisture separator on the compressor will help get rid of water but won't get it all.

   After soldering all the copper couplings blow out the line to get rid of any copper scale that the heating might have caused.  I'd also put in a bleed valve at a low spot to occasionally bleed off any moisture that might collect.

   PlaneWood by Mike_in_Katy (maker of fine sawdust!)
   PlaneWood

1. 
   user-78887 | Dec 28, 2003 06:03pm | #3

   Thanks guys for the immediate answers

   I am on my way to HD

   Best

   Jay

1. 
   ian | Dec 29, 2003 05:53am | #10

   Woa there Jay

   I'm probably too late if you've already been to HD. But me thinks 1/2in copper pipe will be way too small to use for compressed air.   To work an air tool needs a certain volume of air delivered to it a certain minimum pressure.To a first approximation, to deliver the same VOLUME of air to a tool, the (pressure x velocity) inside a 1/2 pipe will need to be about 8 times that inside a 1in pipe.  [the cross sectional area of 1/2 in pipe is only 1/4 that of 1 in pipe and the internal friction (resistance) of 1/2in pipe is at least 2 times that of 1in pipe.] 

   I'd be concerned that your compressor is probably not big enough to deliver the required air flow without premature wear.

   Ian

3. 
   rslatm | Dec 28, 2003 07:31pm | #4

   Type L or K copper pipe is recommended. Type M is considered too thin.

   
   

   ---

   Edited 12/28/2003 2:39:48 PM ET by Rick at Arch. Timber and Millwork

1. 
   EdHarrow | Dec 28, 2003 09:19pm | #5

   Me thinks it's "M" that's too thin...

   Assuming you run the piping along the ceiling, or at least "high", and have connections located "low", use a "T" and a street elbow and go vertically from the horizontal run, before dropping down.  This will help catch water.  All the verticals should also end in a valve so that you can drain them.  It's nice if you can pitch the whole of it slightly so that the water will run to one end, where of course you'll have another valve to drain it.

   If using sensitive stuff, you'll want a good water trap.  It needn't be for the whole system if you dedicate one drop to the sensitive work (spray gun, etc).

1. 
   rslatm | Dec 28, 2003 10:55pm | #6

   Oops! Was in a rush Ed! The textbook way is to have the T going up and drop the line back down so all the water runs down the pitched main pipe either back to the tank or the other end of the line. In big shops the main pipe line is looped so there is no drop in pressure because there is no last station. I've seen so many shops that run airlines like it's a waterline and have a constant water problem. Have a great Ingersol Rand book on running airlines.

   Edited 12/28/2003 2:56:46 PM ET by Rick at Arch. Timber and Millwork

   Edited 12/28/2003 2:57:06 PM ET by Rick at Arch. Timber and Millwork

4. 
   UncleDunc | Dec 28, 2003 11:31pm | #7

   Black pipe will resist a stray nail better than copper will.

   If a small fire melts the solder in a copper fitting, it's likely to turn into a large fire when the compressed air starts blowing on it.

   Folks who live around Houston do need to be more careful about sloping and draining their air lines than people who live around, say, Denver, but I think it's possible to use black pipe successfully even in humid parts of the world.

1. 
   Scrit | Dec 29, 2003 01:31am | #8

   The biggest annoyance about using black pipe is that it rusts and you therefore have to flush-out your pipework every few years and live with filtering everything. Copper doesn't suffer from this problem and explosive decompression can be dealt with by instaling an "air fuse" on the output side of the compressor receiver. In the event of a rapid pressure drop (such as a hose parting) this will stop air flow in milliseconds

   BTW, I use a plastic pipe in my shop designed by a company called Guest. Works beautifully and doesn't go brittle.

   Scrit

1. 
   Doc | Dec 29, 2003 05:30am | #9

   It seems to me that Fine Woodworking had an article awhile ago about running air lines.  Atleast I think it was FWW, but maybe it was another magazine.  I'll see if I can find it.  Maybe someone here remembers seeing it. 

5. 
   VaGentinMI | Dec 29, 2003 05:57am | #11

   When you run your lines suggest 3/4 for main trunk, 1/2 for drops. when you do run your main trunk, put a fall in it so all water will either run back into the compressor, or to other end. W/ drops, do not come off the bottom, but put in an upside down "J" so solid water will stay in main trunk. W/ lines coming off the drops, put a leg below the q/c about 6" & install a valve so you can drain lines periodically, or better yet put in drip legs. Type L is thicker wall than M. When you look at it, you can see diff.

6. 
   mudman | Dec 29, 2003 08:39am | #12

   At a shop I worked at for some years we used copper supply lines and the runs were very long because the compressor was in the wharehouse. Never was a problem running high volume tools (impact wrenches, sprayers). Run the lines high so they will not be damaged. If you are not experienced with sweating you could probably find a plumber to do it for 100 bucks or less.

   Mike

1. 
   user-78887 | Dec 29, 2003 02:02pm | #13

   Thanks to all for your advice.

   I actually havent bought the supplies yet.

   Mike - do you recall if the pipe were 1/2 of 3/4 inch

   Also I checked in the HD catalog and I didnt see a copper fitting that I would need a 1/2" copper sweat <-----> 1/4 NPT thread (male or female)

   I assume they exist

   Best

   Jay

1. 
   UncleDunc | Dec 29, 2003 04:26pm | #15

   >> ... 1/2" copper sweat <-----> 1/4 NPT thread (male or female)

   >> I assume they exist

   Probably a good assumption, but may be less time and effort to use a sweat to thread adapter followed by a bushing or bell reducer.

1. 
   Sphere | Dec 30, 2003 01:00am | #16

   you can also get an auto drain device..on a timer drains the water at the comp..whenever you set it for

1. 
   alanplanesaw | Dec 31, 2003 12:34am | #17

   Sphere,

   you can also get an auto drain device..on a timer drains the water at the comp..whenever you set it for

   Where can I get such a device?  Cost?  Name?

   Thanks,

   Alan - planesaw

2. 
   Sphere | Dec 31, 2003 12:44am | #19

   http://www.autotoolmart.com/cgi-bin/webc.cgi/st_prod.html?p_prodid=9968&p_catid=59&sid=fg1x10mp0KzBir-26103448030.8d

3. 
   alanplanesaw | Dec 31, 2003 02:28am | #23

   Thanks for the info on the drain.

   Alan - planesaw

4. 
   Sphere | Dec 31, 2003 02:39am | #24

   No problem. We used one in the Guitar shop..scared the bgeezus outta me  when I was working late..I thought a pipe bit the dust..painter had it set to drain at midnite everyday..works like a charm and saves a lot of headaches if you have humid days.

5. 
   Scrit | Dec 31, 2003 06:35pm | #33

   Have a look for Norgren on the Inernet. They make automatic drain legs (drain when the pressure is dropped or level gets too high) and timer drain valves to do onto drain legs.

   Scrit

2. 
   mudman | Dec 31, 2003 12:47am | #20

   Sorry, I don't remember what size..... I think it was 1/2". As for the pressure drop problem they are talking about the simple solution is to attach a regulator to a male coupler and plug it in where you need the air. Then you can run the compressor at its max setting and control the presure as close to the tool as posible. Another point is that most air hoses are only 3/8" ID and are usually 25 to 50 feet long. Unless you have a large shop you will probably not need more than 40' of copper. As for the fitting you need a 1/2"(or what ever size copper you use) sweat to 3/4" Fpt, then at HD go to the compresor area and find the bins of little compressor fittings and you can find a reducer there. You can also use 3/8" air couplers this way for better air flow.

   P.S. Test the lines at low pressure (50 psi) for leaks!

   Mike

7. 
   eddiefromAustralia | Dec 29, 2003 02:13pm | #14

   Check with a local compressed air supplier.

   Ian's exactly right - you could be robbing the supply of volume due to unnecessary pressure loss.

   As well, copper loses heat quickly, so expect condensation in the pipe and ensure that you have proper drains.

   I used to have charts for this sort of thing but gave them away when I finished with plant engineering.  A call to Atlas Copco or another compressed air manufacturer with a polite request would have them give you advice - you'll need to know the compressor output (cfm and pressure in psi or bar) and if possible, compressor rated discharge temperature before you call.

   They should be able to provide advice on the spot if you ask to talk to the technical advisor or department.

   Cheers,

   eddie

8. 
   PlaneWood | Dec 31, 2003 09:17pm | #36

   So, after all this, what are you going to do?

   PlaneWood by Mike_in_Katy (maker of fine sawdust!)
   PlaneWood

1. 
   user-78887 | Jan 02, 2004 04:26am | #38

   To Mike and all who have been so helpful with this discussion.

   The short answer is that I have not made any progress with the compressed air system. I have appreciated all the feedback however. In some ways it has made it somewhat more rather than less complicated. I was ready to go to HD and buy some pipe and fittings and put it together last week. But all the information I received gave me pause.

   The other reason is that in my day job I am a hand surgeon and I have been busier than usual ( fortunately not with any woodworkers).

   One of my interests is photography and I have a ton of pictures to frame. As an amatuer wooodworker picture frames are a great thing to focus on b/c it take so little wood and it sharpens skills.

   Once again I do appreciate all the good advice.

   I promise to keep you posted with my progress.

   Best

   Jay