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  #46 (permalink)  
Old 02-09-2006, 07:08 PM
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re: air lines

All good points 'oldred'. I'm just the messenger. Personally, I found the illustration to be most useful for planning my system layout. Galv or black pipe, I don't see a difference. I did find a number of other sources during my research that recommended against PVC (risk of shattering and schrapnel upon rupture) and copper (I don't remember why), although I've also seen both materials used in both commercial and garage workshops.

Cheers!
Garth
http://www.banzairunnerpantera.com

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  #47 (permalink)  
Old 02-09-2006, 09:11 PM
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Galvanized and black iron pipe are exactly the same product except the former has been dipped in liquid zinc for corrosion protection. They are made exactly the same way with an electric resistance welded seam down the side. Neither are cold rolled in the technical sense of the word. Galvanized is intended for water service and black iron is intended for natural gas service since the gas doesn't like zinc and corrosion protection isn't needed with gas. They make a version of the black iron pipe that is bare internally and has a powder coating on the outside for corrosion protection in direct burial service, again as gas line. The more expensive option in the steel line is seamless tubing but that is significantly more expensive and not need in this relatively low demand service. I would avoid black iron in compressed air service since the air will expose the unprotected steel inside the pipe to water condensate and oxygen = rust build-up. Galvanized is the better choice by far for that reason.
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  #48 (permalink)  
Old 09-17-2006, 09:25 AM
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Water vs Air pressure

Water pressure is hydraulic pressure. Air is compressed pressure. When a hydraulic system fails, the pressure drops instantly. When compressed system fails the pieces can fly and whip. While the small shop system may not have very much pressure, you may, down the road, up grade the compressor. Error on the side of safety.
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  #49 (permalink)  
Old 09-17-2006, 11:53 AM
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Go with steel, the reason being= one of the largest manufactures of pvc fittings in the country does not recommend using pvc foe compressed air or gas. click on the specifications for sch 80 fittings and scroll down
http://www.spearsmfg.com/product_dimensions_spec.htm Their products are some of the highest quality out there and if they say no there is a good reason for it.

The suggestions for drains at each drop are to drain condensation. A T with a valve below it on each one will do a lot to extend the life of your air tools and will help keep water out of your paint work.
Also Rig your air compressor tank so that you can drain it on a regular basis easily. This will help extend the life of everything in the system.
Definitely have a flexible hose/line between the compressor and the piping, the same size as the pipe if at all possible.
If you live in an area that has irrigation supply stores (The ones that sell pipe pumps and sprinklers to farmers) check their prices on all pipe and fittings. There is usually a huge difference over hardware stores or the box stores that sell home repair stuff. A bit of diligent price shopping will save a quite a bit here.
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Old 09-17-2006, 08:51 PM
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http://www.tptools.com/statictext/ai...ng-diagram.pdf

This site says that you can use 1/2" pipe for up to 75' horizontally. I'm sure the flow rate would be enough for running one tool at a time but would moisture be a problem when painting. Other diagrams that I have saw say to use at least 3/4". If you use 3/4" line it will have 50% more surface area for cooling. The air will move about 2.25 times faster through the 1/2" so it will have less time to cool. I've been debating the last week or so wether to go with 3/4" galvanized or 1/2" copper. I'd rather go with 3/4" copper but the price is a lot higher. Will the 1/2" copper cool enough with about 55' of pipe to get enough water out or would the 3/4" pipe get additional water out? I wouldn't want to ruin a paint job because of the pipe being too small.

Danny
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  #51 (permalink)  
Old 09-18-2006, 03:33 PM
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I can't see any advantage to copper unless you want to polish it up for looks
Kind of like the military lateine brass work that us old vets had to polish back when.
Draw your pipe layout out on paper and you can tell what you will need. Unless you have a big shop you won't have that many outlets to connect a hose to. They need to be in convenient spots where you don't have to drag long hoses but most 2/3/4 car shops don't have a great number of drops to connect a hose to.
I always use a water trap/filter between the hard line and the airhose to the paint gun when doing any paintng. Also I am in the habit of draining my compressor tank on a regular basis, and I drain it before starting any major paint work.
As I mentioned in a previous post it just flat helps make your air tools last longer without repairs if you keep the condensation drained out of the tank. My CP 727 1/2 impact is 33 years old and has never been to the repair shop.
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Old 09-18-2006, 03:49 PM
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Chopt, Copper offers a big advantage in helping to keep the moisture out of your air lines due to the better cooling over iron pipe. This advantage is lost over long distances of about 100 ft and farther but for the short runs commonly found in a small shop or garage it can be a big help. With the prices of copper today it may very well be that iron pipe with a precooler is the most logical choice.
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Old 09-19-2006, 09:06 AM
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Go Copper

I did my lines with 1/2" galvanized pipe, joints taped with teflon tape. The syatem slowly leaks down if I leave the main valve open. If I were to do one again, I'd do it in copper, sweat soldered.

-jwk-
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  #54 (permalink)  
Old 09-19-2006, 08:38 PM
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I went ahead and bought the 3/4" galvanized today and a HF pipe threader. I just couldn't justify the price of copper no more than I will use the system. I'll just use 2 dropdowns in my approximately 55' and hope for the best. Is the expensive pipe dope worth the extra money to avoid leaks? I bought the almost $3.00 small can but would take it back and buy the $7.20 something small can if it is better.

Danny
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Old 09-19-2006, 09:48 PM
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Doping It

In my experience, good thread sealer would greatly decrease the chance of slow leaks. Good idea going with 3/4 also, it will act as a bigger reservoir as well as increasing flow. Drains at the low points of the system are good. Also, I used big industrial sized quick connects for the flex line connecting the compressor to the manifold, and a ball-valve shutoff. To keep peace in the household since it's in an attached garage, I added a 220V timer that cuts the power so it cannot start up at 3:00 in the morning!

good luck!

-jwk-
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  #56 (permalink)  
Old 09-20-2006, 12:03 PM
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I put temporary PVC air piping in my garage, just to paint my car, but, after reading this post and a couple of others, decided the risk plus the amount of water carryover required me to change to copper. While pulling the PVC down, I wasn't particularly careful - going to the dump - so just kind of yanked it around. EVERY JOINT but one fractured at the fitting. Just for the heck of it, I took my tubing cutter and cut about 1/2 way thru near that one fitting that was still whole, gave it a yank, and "lo and behold", the pipe fractured at the fitting and the place that I partially cut bent but stayed whole. My guess is that the glue has a molecular effect on the base material, and weakens it to the point that a good shock or pressure will 'kill' it.

Before anyone asks, the pipe was made by Charlotte Pipe on May 1, 2006, and I purchased it from Home Depot and installed it over the July 4, 2006 weekend.

I have installed about 40 feet of copper - 1/2", and now feel fairly safe. It still has some water carry over, but I will put a precooler after the compressor and make up a good trap system at the far end, using a HF as a knock out trap and a Sharpe 707F ( due in via UPS today ) as my final last chance line filter - then a bulb trap at the gun - too much work to redo a paint job.

See this thread as well :Piping questions
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  #57 (permalink)  
Old 09-20-2006, 06:42 PM
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Kampr, I used harvey pipe thread compound on mine & it works well only losing 10psi over 2-3 days. Make sure you have decent pipe wrenches to get everything good & tight & wear old clothes because it's messy & doesn't come out very well. First few connections I overdid the compound but used less from then on, doesn't take much. Get some unions so you don't have to tear everything apart to change something down the road.
Good Luck
Steve
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  #58 (permalink)  
Old 09-20-2006, 08:44 PM
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Quote:
Originally Posted by krehmkej
In my experience, good thread sealer would greatly decrease the chance of slow leaks. Good idea going with 3/4 also, it will act as a bigger reservoir as well as increasing flow. Drains at the low points of the system are good. Also, I used big industrial sized quick connects for the flex line connecting the compressor to the manifold, and a ball-valve shutoff. To keep peace in the household since it's in an attached garage, I added a 220V timer that cuts the power so it cannot start up at 3:00 in the morning!

good luck!

-jwk-
I find the occasional late night compressor start keeps things interesting.....
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  #59 (permalink)  
Old 09-22-2006, 11:59 PM
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Oldred, I did a bit of research on the subject and what I could find via a google search was some wood workers contemplating rigid copper tube as airlines. http://www.woodweb.com/cgi-bin/forum...pl?read=395135
Also http://www.woodweb.com/cgi-bin/forum...pl?read=401701
Another site occupied by folks who seem to be a bit better informed.
http://www.ridgidforum.com/forum/arc...php/t-528.html
It may look nice and impress the buddies but I really don't think that the geewizz factor would be worth the extra expense and effort.
In 40+ years of going into different shops and working in several professionally I have never seen or heard of copper airlines before this thread.

The whole idea is to NOT get water in the lines. Condensation comes from the process of compressing the air. One needs a decent water trap and filter in close proximity of the tank. One also needs to keep the compressor tank drained of water on a regular basis. If a guy does those two steps he won't have to worry about water in the lines.
Normal procedure for most folks who paint is to have a trap/filter either at the drop or one of the small inline filters at the gun. I prefer the quart size trap at the drop simply because i find that for me the inline filter gets in my way.
I worked for the Pontiac dealership in Waco Texas in the early 70's, standard procedure was for one of the service writers to turn off the shop air compressor and open the drain valve at 5pm every day. The place probably had/has 300 linial feet of iron pipe airline. I never saw water in the line and still use the same air tools that I had then. If you were to walk into that shop today I would imagine that they still have the same air line system that they had then.

Last edited by Chopt 48; 09-23-2006 at 12:28 AM.
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  #60 (permalink)  
Old 09-23-2006, 01:17 AM
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Quote:
Originally Posted by Chopt 48
[...]

The whole idea is to NOT get water in the lines.

[...]

Normal procedure for most folks who paint is to have a trap/filter either at the drop or one of the small inline filters at the gun.

[...]
But I thought the whole idea is to NOT get water in the lines. What's with the trap/filter at the drop and the inline filters?
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