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  #16 (permalink)  
Old 01-09-2004, 04:59 PM
RetroJoe's Avatar
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Phil, put in an inline water trap and you should be ok. I found a web site that had some really good info on installing a airline setup, but I can't remember where I saw it. I will do some further research once I get to work and have access to the spiffy T-1 lines! It makes research much easier! Joe

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  #17 (permalink)  
Old 01-09-2004, 08:28 PM
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Hi all, I'm a newbie to this board but,I'm a certified GEEZER and have some experience with WOG/steam piping.(retired Navy chief,millwright,machinist,weldor/fabricator,Bach.M.E./P.E.)
Here are some things to think about when you install a shop air system...
*Sch. 80 plastic pipe is fine for a home shop,CPVC is an upgrade, be sure to use Sch. 80 fittings, slip/glue, not threaded. Use CPVC glue and cleaner on CPVC. PVC glue will not bond corectly to CPVC, and some fittings are hard to find in CPVC (Yea, I know, the kid at home desperate don't know the difference, teach him!)
* CPVC is slightly stronger than PVC, but it's real advantage is the UV inhibitors, it lasts much longer, is less temperature sensitive,and besides,black don't show the dust as bad!
*Pitch the horizontal runs about 1/16 " per foot rise, away from the volume tank,(to allow the condensation to return to the tank)for large shops, 2500 sq.ft. and up, a volume tank on each end of the system and a larger dia. pipe feeding at the center will help control condensation.Support it at 3 points per 10 feet of horizontal run length. (Yea, I know,that sounds like a lot of support, but a year from now your system won't look like a split rail fence...)
*all the taps should be made from the top of the line, use a fitting called a return bend,(looks like a 180 deg. elbow)to make your drops, a drip leg and a pet**** on each drop is overkill, but not a waste of time and materiels...
*put as many taps as you can afford in the system when you build it,(every 10 feet is a good start, every 5 is better)put drops in where you need them first, you can fill in others later, as you have spare buck's, solidly anchor each drop to the wall, at the connectors,sooner or later, you will trip on an air hose and rip it right out of the main line... that ain't no fun. don't forget one by each door.Wait for the combo filter/regulator/water traps to go on sale at harbor freight,one on each drop ain't to many...
*Don't connect the plastic pipe directly to the compressor, a 3 or 4 foot piece of high pressure hose will stop vibration from shakin' your system apart.I usually add a 10 foot length of 3/4 in. soft drawn copper tube to help dissipate heat.(don't roll it up in a coil, it will trap water(condensate) and make the damnedest noises late at night... think moonshine still, gravity works!
*Runs over 50 feet can be up sized to 1 1/2 dia. to reduce friction loss and volume restriction,1 in. drops will support 2 connections with very little volume loss.
*running pipes in the slab sounds like a good idea, but unless the average humidity is less than 20 % in your area, you have just built a very expensive, in ground sprinkler system/water trap, and north of the mason - Dixon line , it will freeze...
*Auto blow down valves are a gift from god for us old farts that can't remember the last time we blew down all tanks... C-YA Paul
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  #18 (permalink)  
Old 01-09-2004, 09:00 PM
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Thumbs up

Wow olsixrod, that's some excellent info! Thanks. I'll use it as a guide when I do mine which is very soon.
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Old 01-09-2004, 09:41 PM
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Here you go Phil, http://www.oldsmobility.com/air-compressor-piping.htm

Last edited by RetroJoe; 01-09-2004 at 09:41 PM.
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Old 01-10-2004, 07:19 AM
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Thanks Joe! That's a great link. I bookmarked it. Excellent info with pics!

Later,

Phil
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Old 01-10-2004, 05:25 PM
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Here are some articles I had on Air line layout:

For the average do-it-yourselfer working at home in a small garage, air lines from the compressor are something not given a great deal of forethought, since most activities are not extremely air-intensive...that is, requiring a large volume of compressed air. For these people who might be occasionally using an air ratchet or inflating a tire or two, their portable compressor will work just fine and really require no additional planning. However, once you decide to really give your compressor a workout with a sandblaster, paint-gun or die grinder, the volume of air demanded by these tools require some rethinking in choosing an air compressor and how the air compressor's air lines are set up.
Choosing an Air Compressor

"images/aircompressor1.jpg"

"images/aircompressor1.jpg"The most commonly-made mistake is the purchase of a compressor which is too small for the work to be done. In figuring what size a compressor you'll need, do some research. A 60-gal upright compressor with a single-stage pump and a 5½-hp motor might seem like the ticket (or even a little bit of overkill) for the home user, but when you start looking at the CFM (cubic feet/minute) this compressor is capable of, you'll see that most are rated in the neighborhood of about 10-13 CFM, which for the most part is inadequate for sandblasting or painting. This type of compressor (pictured at right) is about the best single-stage compressor you're going to find, but a dual-stage compressor (with two pistons) will not have to work as hard, minimizing heat and water buildup in the compressed air. For the financially-impaired, the single-stage compressor CAN be made to work adequately, however...providing the user take frequent breaks to allow the compressor to catch up and to cool off. If the compressor is running full time, it's too small and will burn up in no time at all.
One of my favorite quotes, and one I TRY to live by, says:
"It's better to have it and not need it, than to need it and not have it".
This is especially applicable with air compressor selection. Always buy more compressor than you think you'll need, because if you have it, you WILL use it.

Air Compressor Piping Rules Of Thumb

· After leaving the air compressor, air line pipe goes straight up the shop wall as high as possible. This helps minimize any water from leaving the compressor and traveling through the pipe.
· Slope main lines at least four inches (10 cm) per 50 feet (12.7 m) of pipe away from air compressor so that condensate travels with the flow of air and away from the compressor. As warm air leaves the compressor, it cools and thereby condenses as it travels through the pipe. This water vapor, a problem in itself, can also cause scaling and rusting inside the piping. Install drop legs for condensate removal.
· The first air drop should be at least 25 ft. (6.4 m) from the compressor although 50 feet (12.7 m) is optimum. This allows the compressed air to cool to room temperature so any condensation can occur before it gets into the water separator.
· Take-off comes from the top of the main air supply line at each air drop. This reduces the risk of water and other contaminants from traveling down the drop into the water separator.
· Use carbon steel pipe as discharge pipe material. Never use PVC or ABS. (PVC is easy to work with, but will not allow the hot air to cool quickly enough to condense the water in the compressed air. Also, in case of a compressor regulator failure, if the PSI inside the line were to go above the rated safety capacity, the plastic pipe won't just split, but will actually explode, producing razor-sharp projectiles which are sure to damage property and person.) Consider using Schedule 40 black iron, galvanized, copper, stainless steel, or anodized aluminum. Size the pipe for maximum CFM required. This will equal full load production plus future expansion plans. (See chart below)

· Use large enough pipe so as not to exceed 3 PSIG pressure loss through the entire line. (The target is a maximum 10% pressure drop through the entire system, i.e. from air compressor to farthest drop.)
· Discharge pipe is to be the same size as air compressor outlet.
· A shut-off valve should be installed before each point-of-use filter. This allows air supply to be shut off for filter maintenance.
· Install a pipe tee in the discharge pipe to blow to atmosphere if necessary for control and adjustment. This will also serve as a convenient connection for a rental compressor if required.
· Install pressure gauges throughout the system for troubleshooting. Locations should include the receiver, headers, tools, production equipment and the end of plant piping system.
· Use long radius elbows. Try to use flow resistant fittings and valves. Use ball or butterfly valves.
· Locate headers and sub-headers near air uses and manufacturing equipment. A loop system is ideal, providing two way flow distribution.
· Do not connect multiple air users to the same drop. Use one drop for each air user.
· Install an air receiver at intermittent high demand points such as occasional sandblasting, air motors, etc. Air receiver size should be one gallon of storage per 1 CFM of air compressor output as a minimum in order to permit the compressor controls to operate correctly.
· Always consider leakage and future expansion in order to eliminate compressed air system obsolescence. A 10% per year growth rate is common.
· Drain Valves: The daily draining of the system at each outlet disposes of the contaminants that build up in the air supply. Drain the compressor trap daily if equipped with a manual drain. Increase draining intervals appropriately during periods of heavy use.
· Be sure to read and understand equipment instruction and installation manuals and discuss the layout and piping requirements before installation.
· Proper maintenance of the air compressor can reduce airborne contaminants such as particles and oils, and reduce heat and operating cost. Check air filters, oil level and perform regular maintenance per operator's manual.

Capacity Main
Using the diagrams and tips listed above, I designed and installed the following air compressor piping layout in my own garage, using ½" copper pipe. Compared with previous attempts at using PVC with no droplegs, the new layout works beautifully, and does an excellent job of filtering out every drop of moisture, ensuring my paint gun and sandblaster is only supplied with a steady stream of cool dry air. The droplegs catch 90%-95% of the moisture, allowing the water separators to easily remove anything remaining.

*SEE DRAWINGS IN “AIR COMPRESSOR LAYOUT” FOLDER

Air Line The size of the pipe is critical!
Pipe diameter must be of sufficient size for the volume of air being passed as well as the length of pipe used. This will minimize pressure drop.
Did you ever have only 60 or 70 pounds of pressure at the spray gun or other tool when your compressor should deliver 100 pounds? Using pipe that is too small in diameter can cause this pressure drop.
For example, if an air compressor delivers 100 psi through a 100 ft. pipe, 1/2-inch in diameter, there's greater pressure drop than if a 3/4-inch diameter pipe were used. Use the chart below to match your compressor's size and capacity with the optimum pipe size.
DISCHARGE PIPE SIZE CHART
Compressor
Size Compressor
Capacity Main
Air Line Min. Pipe
Diameter
1½ & 2 HP 6 to 9 CFM Over 50 ft. ¾"
3 & 5 HP 12 to 20 CFM Up to 200 ft. ¾"
Over 200 ft. 1"
5 to 10 HP 20 to 40 CFM Up to 100 ft. ¾"
100 to 200 ft. 1"
Over 200 ft. 1¼"
10 to 15 HP 40 to 60 CFM Up to 100 ft. 1"
100 to 200 ft. 1¼"
Over 200 ft. 1½"
Courtesy of DeVilbiss, an Illinois Tool Works Company


And I had these pics saved also. Hope it helps someone out.









Kevin
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  #22 (permalink)  
Old 01-11-2004, 10:47 AM
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Don't use PVC

When I finally replaced my PVC lines with copper, I was amazed how brittle the PVC had become. I was lucky that I had only one blowout. If you are not in your shop, and the lines fail, unless you have shut off your compressor off, it will run until you get back. My shop is 100' from my house, so it could have run for days..........

I replaced all the lines with 3/4" copper. Easy to run.
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  #23 (permalink)  
Old 01-11-2004, 01:26 PM
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The garage that I have now does not have air lines run in it right now. I have not been able to find the walls since I moved in from a much larger garage. The last garage had air lines all over. They were PVC lines. The compressor was on 24/7 and the only times that the pressure was off the lines, was when I got a "wild hair" and did maintenance on the compressor. They were about 8 years old when I moved. The only problem that I had was when my brother hung a metal drop light(turned on) on one of the lines.. The heat from the metal light cage started melting the line. That's not a concern anymore, I drove over that light. I had mine connected to the compressor with copper tubing that was rolled to reduce the vibration on the PVC.

That all worked for me. Maybe it shouldn't have, but it did.
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  #24 (permalink)  
Old 01-12-2004, 06:33 AM
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Hmmm, the article that Kevin provided mentions that it's not a good idea to use PVC because of it tendancy to not cool air.

Quote:
Use carbon steel pipe as discharge pipe material. Never use PVC or ABS. (PVC is easy to work with, but will not allow the hot air to cool quickly enough to condense the water in the compressed air.
I'm sure for the occasional use that I'll be typically doing, PVC will be fine. But, I'll probably curse it when I get into one of those 12 hour jobs that will require me to use the compressor a lot. It seems there's always a trade-off. LOL
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Old 09-27-2005, 10:40 PM
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air lines...

with all the posts on this..everyone should keep a couple of things in mind. What kind of job do you want in the end? PVC is the worst for air lines for a couple of reasons one of the biggest is condensation in the lines which is not only a killer of compressors but also of air tools,air hoses and if you are considering painting with any high quality paints..your finished product. Not only is condensation in he line but you also have some oil and silicon, which is bad for paint jobs and some tools. Of course air pressure is another factor if it hasn't exploded or faulted IT WILL eventually and who do you want to get hurt if your not there (kids playing in the garage, ect..!!). Copper being the best to use for lines, 2nd is steel (black) and have at least 20+ feet of line with at least two down spouts with petcocks PRIOR to the airfilter (hopefully with guage) to run your lines off of. With this you are guarenteed more life from your compressor and less pulling your hair out on all the other jobs that you do in the garage. sorry for the long post.
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  #26 (permalink)  
Old 09-28-2005, 05:47 AM
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Yeah, The more I read about it, PVC is NOT the way to go for sure. I ended up using black iron pipe. I've got a good preliminary feed started and am going to add to it over the winter gettin a couple runs closer to the front at the overhead doors. I'm even going to put a line by the back side door for pumping the kids bike tires up and the floats for the pool. I did also allow for drains to release water at a couple areas and will have one at each extreme end of the system too.
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  #27 (permalink)  
Old 09-28-2005, 09:15 AM
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Pvc Not Suitable

This has been hashed out over and over. PVC pipe is *not* suitable for compressed air lines. Even the manufacturers of PVC pipe recommend against it.

http://www.ppfahome.org/pvc/
Quote:
PVC piping systems should not be used to store and/or convey compressed air or other gases. PVC piping systems should not be tested with compressed air or other gases either.
http://www.osha.gov/dts/hib/hib_data/hib19880520.html
Quote:
The Department of Labor and Industries warned today that plastic polyvinyl chloride (PVC) pipe cannot be used in compressed air piping systems without the risk of explosion.

When PVC piping explodes, plastic shrapnel pieces are thrown in all directions.

"We're seeing more incidents of explosive failure, and we're citing more employers for using PVC air system piping," said Paul Merrill, senior safety inspector in L&I's Spokane office.

"It's probably just a matter of time before someone gets seriously injured in one of these explosions unless everyone pays more attention to the manufacturer's warnings," Merrill said.
http://64.233.167.104/search?q=cache...=en&lr=lang_en
(A PDF document HTML-ized by Google, original at http://www.cbs.state.or.us/external/...-89-06(rr).pdf )
Quote:
The problem with PVC piping is that low temperatures and stress can cause an explosive failure which sends shards or shrapnel flying. Thermoplastic pipe manufacturers and the Plastic Pipe Institute recommend against use of PVC pipe in exposed conditions. (Refer to Plastics Pipe Institute recommendation B revised October 1989)
http://www.osha.gov/pls/oshaweb/owad...ONS&p_id=20202
Quote:
Since PVC material does not possess shatter resistant property, and since it is very clear from the industry's recognized practice that PVC pipes are prohibited for above ground transportation of compressed air and gases (unless the pipelines are encased in shatter resistant material), any such use by the employers, where employees may be exposed to hazards, will be in violation of Section 5(a)(1) of the OSH Act. Therefore, employers who are found to violate the above described conditions or manufacturer's recommendations, during an OSHA inspection, shall be issued a 5(a)(1) citation.
[Bold emphasis added]

If you're determined to have plastic piping, at least look at things that meet some ASME standards, like http://www.garage-pak.com/faqs.cfm
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  #28 (permalink)  
Old 09-28-2005, 01:43 PM
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I believe that SCH 40 PVC pipe has a pressure rating of 400 psi and I don't see any of us going that high on pressure. As for condensation I just got done painting my truck and I had one separator in line and while just using the blow gun one day I noticed I had some water in it so I put a mini separator with couplings right after it and when got done painting I had water in both of them but none on the truck.

David
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Old 09-28-2005, 02:18 PM
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PVC pipe NOT suitable for airlines

Quote:
Originally Posted by Bluepen
I believe that SCH 40 PVC pipe has a pressure rating of 400 psi and I don't see any of us going that high on pressure.
David
PVC pipe has its pressure rating stamped on it. That is maximum, non-shock working pressure at 73 degrees F. You are applying shock loads on that pipe every time you pull the trigger on a blow gun, air tool or spray gun. Does your shop stay at 73 F all the time? At 120 F, that maximum, non-shock working pressure is de-rated to 0.40 of that printed on the pipe. For 3/4" sched. 40, that leaves you with 192 PSI, non-shock, maximum, NEW. Sure doesn't look like much of a margin of safety to me.

PVC pipe manufacturers warn against even testing piping systems with compressed air. Water is not compressible. If the pipe bursts when filled with water, you lose pressure and get a wet floor. Air is compressible. If the pipe bursts when pumped with air, you can get shards that are accelerated by the escaping, expanding air.
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Old 09-28-2005, 03:21 PM
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Grouch, Of all the arguments made here, both pro and con, what you have said sums it up better than any so far and best explains why there IS a difference between air and water pressure. Also as you pointed out that pressure rating is only good for a narrow temperature range and even that becomes meaningless if the pipe is accidentally subjected to even minor damage such as a blow from any hard object sharp or not. And what about cold temperatures? What happens to that pressure rating if the line is exposed to winter time cold while under pressure? The bottom line here is that plastic is far more likely to fail in the first place and if it does you get an explosion instead of a leak.
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