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  #61 (permalink)  
Old 09-23-2006, 07:57 AM
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Quote:
Originally Posted by grouch
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?
Most of the water condenses out WHEN the air cools. I have a water trap at the compresor outlet, automatic tank drain, and still use water traps at the drops, as anytime there's a pressure drop, more condenses out.

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  #62 (permalink)  
Old 09-23-2006, 09:45 AM
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Chopt, With all due respect you are wrong on both points the water is supposed to condense in the lines and close to the tank is the absolute worst place you could place the separator, even your theory about the condensation defies the laws of physics. The water enters the compressor as a vapor in the air with the amount depending on the humidity. This air will reach a high temperature during compression and if you can remember your high school physics you will know that the hotter the air the more vapor it will contain. Until the air is cooled the water will REMAIN in vapor form and pass through most mechanical separators largely unaffected where it will then condense in the air lines as it continues to cool finally exiting as liquid water in your tools or paint gun. The idea IS to cool the air with the supply line from the tank but before the separator so the vapor will condense there and drain into collection drops where it will remain unaffected by the air flow until such time that it can be drained. Some vapor will inevitably condense in the tank as the air cools there collecting on the tank walls and draining to the bottom of the tank where it will remain until it is drained and thus will not enter the air line so what is the logic of locating the separator close to the tank? This is not just my idea of how this works but is standard accepted practice and is commonly used everywhere and if you will search right here on this forum you will find engineered system diagrams from Sharpe outlining exactly what I have described. Maybe you have been in and out of shops for many years but just for the record I have installed systems as part of my welding and mine service for over thirty years and yes Copper is commonly used. The last job I did before I retired this past year was a mine shop in Ky that took nearly 1500" of 1" copper line and was plumbed as per the building prints exactly as I have outlined, but then maybe the engineers that designed that building don't know squat about what they are doing.
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  #63 (permalink)  
Old 09-23-2006, 09:55 AM
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Krehmkej, The trap at the tank is allowing most of the water to pass through as vapor since it more efficiently separates liquid and will remove little or no vapor depending on the type of unit but in any case it works FAR better down stream of the supply lines and drops because the air will have cooled and the vapor will have condensed into liquid. The idea is to condense as much vapor as possible BEFORE the air enters the separator unit otherwise the only thing left to trap the water as the vapor condenses is the drops where some of the water will drain but any water that does not collect in these drops will be carried out in the air stream as droplets that would have been collected in a properly placed separator. You said it yourself, the vapor condenses WHEN the air cools but the air coming out of the compressor is at the highest temperature it will be anywhere in the line!
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  #64 (permalink)  
Old 09-23-2006, 10:48 AM
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Very well put, oldred! As a rule of thumb, the closer to the compressor that a water trap is placed, the less effective it will be. Warm, moisture-laden air will pass through a filter more readily than liquid will. So it stands to reason that you want the filtering done AFTER the water has tranformed into liquid, if that makes sense.
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  #65 (permalink)  
Old 09-23-2006, 12:28 PM
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CD, That does make sense because that's exactly how it works.
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  #66 (permalink)  
Old 09-24-2006, 10:11 AM
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Well, I guess a day that one doesn't learn something new is a wasted day.
The shops that I was referring to were regular auto dealerships and independent repair shops and tires stores. Also the fruit juice processing plant that I did the maintenance purchasing for had thousands of feet of airline, all black steel. we did have special refrigerated dryers on certain pieces of equipment. Every major piece of equipment in the plant had/has air operated equipment on it.
The only place that I have run into extreme water in the lines problems was at a dairy ( It milked 800 cows 3 times a day) where the compressors ran 24/7 and were never drained. I could drain several gallons of water out of the tank at a time but couldn't convince the owner that it had to be done daily. They did have extreme valve and actuator problems.
I didn't take high school Physics. I'm not sure that it was even offered at the time when I went to school. I did take three years of auto mechanics in high school, two years of automotive trade school, 15+ years of working as a mechanic in independent shops, dealerships and tire stores and I taught high school auto mechanics for 13 years. That is what I base my experience on and automotive applications use steel/iron pipe to run airlines.
After reading on several web sights I do have to agree that copper lines may have the advantage but I don't see them as a necessity in a home shop application. What I do see as a necessity is putting some thought into the design of the system to help keep the water out of the system.
How about comming up with a drawing of a practical system that the average hobby mechanic could use as a basis for his system.

Now back to the original discussion: are we in agreement that pvc isn't the way to go as far as air lines go? Safety has to be the main concern in any installation before cost, appearance, condensation issues or ease of installation.

A few more interesting web sites on the subject
http://www.gosuburban.com/aftercooler.html
http://www.woodweb.com/knowledge_bas...ry_system.html

Last edited by Chopt 48; 09-24-2006 at 11:14 AM.
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  #67 (permalink)  
Old 09-24-2006, 11:42 AM
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Quote:
Originally Posted by willys36@aol.com
Liquid and air pressure are the same. There is more stored energy in air (compressible) but the pipes are so small, there isn't much that happens when one blows. It just splits and relieves itself. Pressure vessels with a large volume is where things get really dicey if it decides to blow. Can take out the entire building! I have had SCH40 PVC system in my shop for 11 years of 110F summers and 40F winters with no troubles. My walls are open stick frames. If I drywall my shop some day, I'll convert to iron pipe.
I agree, been using it for longer than 15 years, 1" sch 40 white PVC. run 125-135 psi on the compressor, never a problem .......BUT....
remember: if you stand a 20 foot or even a 10 foot piece up in a corner and it falls, double check it before you use in in your system. It doesn't slap against the concrete well/
remember: try to keep all the threads on the PVC MALE. when screwing a piece of iron pipe into a PVC female adapter, if you overdo it, it's pretty easy to split it.
And for god's sake for safety, let all your glued joints set for about 8 hours (my guideline here, guys, not trying to start a big rats nest ) before you pressure therm up.
I will never use anything else. (You can't afford copper right now, anyway, would be cheaper to use welded GOLD or something)
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  #68 (permalink)  
Old 09-24-2006, 11:57 AM
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I never even hinted that Copper is necessary and in fact I have even suggested several times lately that iron is now a more reasonable choice because of the ridiculous cost of Copper. When Copper was more reasonable, or even now if cost is no problem for someone, it offered a significant advantage over iron and the smaller the shop, or least the shorter the line, then the more advantage it has. In all probability all that Copper in that shop I mentioned was, because of the length, a waste as far as cooling and it was chosen because of the (IMO over rated) rust problems of iron pipe. Galvanized pipe would have worked just fine with no rusting but there is the (again much overrated IMO) flaking problem so they chose to use Copper. I will say to anyone who has used either black iron or Galvanized that they should not feel like they have settled for an inferior system because, although Copper may be the best all around choice, the advantages of using it are not so great as to warrant spending a lot of money for.
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  #69 (permalink)  
Old 09-24-2006, 11:59 AM
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Chopt 48: I'm still looking for where someone said copper line is a necessity, since that seems to be what you're arguing against.

Quote:
Originally Posted by onenew32
I agree, been using it for longer than 15 years, 1" sch 40 white PVC. run 125-135 psi on the compressor, never a problem

[...]

I will never use anything else.
Glad I don't live near you. Sometimes people get away with doing dumb things for a long time; sometimes they don't.
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  #70 (permalink)  
Old 09-24-2006, 12:06 PM
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One, When a PVC pipe ruptures it DOES NOT JUST SPLIT! It sends razor sharp shards in all directions and can be extremely dangerous! You may have used your system for 15 years or even 20 but that does not make it safe and every day older just makes it less so. If you are willing to take the risk of using this stuff after all that has been pointed out about it then I doubt if there is anything more we could say to change your mind but PLEASE don't come here and try to convince anyone else that it is ok because it is NOT ok, it is dangerous whether you believe it or not
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  #71 (permalink)  
Old 09-24-2006, 12:16 PM
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Thats a big 10-4, oldred. I would never even consider using PVC for high-pressure air lines, I dont care what its rated at. I did enough dangerous stuff when I was younger, I dont need to be doin it now
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  #72 (permalink)  
Old 09-24-2006, 01:12 PM
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About condensation, I have a 30 foot hose between the regulator and water trap. It gives the air a chance to warm up and the water to condense before hitting the water trap. This setup has been very effective for me.

Here's a diagram.
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  #73 (permalink)  
Old 09-24-2006, 04:38 PM
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Quote:
Originally Posted by grouch
Chopt 48: I'm still looking for where someone said copper line is a necessity, since that seems to be what you're arguing against.



Glad I don't live near you. Sometimes people get away with doing dumb things for a long time; sometimes they don't.
Grouch, trust me when i say i am just as glad you don't live next to me. moderator, the next time you put one of those cute flags on my account wanting to know why i haven't posted in a while. please refer to this thread. Bottom line here: i don't care what you use for air line. the question was asked for peoples input, and i gave mine. i hope it was taken as it was offered by some.
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Old 09-24-2006, 05:14 PM
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And we hope that no one takes it as a safe thing to do. Everyone is encouraged to express their opinion but there is a responsibility to not lead someone to do anything dangerous and in spite of what you apparently believe the jury came back a long time ago on this one. MSHA and OSHA both baned PVC for compressed gas, including air, except when buried or inside steel conduit because of numerous accidents involving flying shrapnel from ruptured PVC lines. It is totally irresponsible to tell someone that using this stuff is a good idea when the dangers of doing so are so well known and if you want to do something like this that is your business but remember this-It DOES happen, there have been injuries from using PVC and it CAN happen to you! honestly who are you really trying to convince?
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  #75 (permalink)  
Old 09-25-2006, 06:45 AM
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Quote:
Originally Posted by oldred
, there have been injuries from using PVC and it CAN happen to you! honestly who are you really trying to convince?
Not sure if it was this thread or another - my shop is a basement garage that in NYS would be illegal to use as an auto parking area on a daily basis. It is fine for work, as long as there is no gasoline in the tank - it is plumbed for air using copper. The daily use 2 car garage was not plumbed. In order to paint my project car I needed to install some air piping, at least TEMPORARILY. I chose .75 PVC for short term use. After doing a search, and reading several posts, decided it wasn't safe. I loosened it up and as it came free of the clamps, EVERY joint but one fractured !! I then did an experiment with my tubing cutter and cut a notch about 1/2 way thru the PVC about a foot away from that unfractured joint. I then gave it a yank. The PVC then fractured at the joint and only distorted at the cut until it was pulled and twisted even more. My unscientific test told me that the cement interacts on a level that weakens the main material.

We all have our opinions on what to use. After this experience, my only opinion is that I will never use PVC for an air transport medium again.

This forum and any threads it contains are for several reasons - transmit information that can be corroborated and are fact, next, they are to transmit opinions based on a persons experiences or knowledge, additionally, they are often fun and sometimes funny. There are many people that have established a level of integrity and what I feel, honesty.
While I have never met a single person that subscribes here, feel that a rapport has been established with several - and I don't always agree with them !!!

What these forums are not is a place to vent major disagreements and personal crusades - and yes, I did get involved in a short disagreement - but I apologized as did the opponent. It ain't gonna happen again.

Dave
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