captainron

captainron

Well Known Member
A recent thread on air compressors had me taking another look at the system in my workshop. With all the fittings in the system, there are bound to be a few nagging leaks. I could shut off the valve at the compressor outlet where it feeds the system, but in a couple of days much of the remaining pressure in the lines would be lost. I've tried to seal fittings with teflon tape, pipe joint compound, or a combination of both. Leaks could be detected with a pipefitter's product called "Snoop", or just a bottle of the play liquid stuff kids use to blow bubbles. Brush it on the fittings and check them in a few minutes to check for bubbles.
Anyway, I've found that just taking the problem fittings apart, running a dab of Permatex Blue RTV around the male threads and re-assembling the joint works better than anything else so far! Let it cure for an hour or so and you're good to go! Much better than just trying to wrench the fitting some more. With this stuff, fittings can be assembled with little torque required.
 
Air Leaks - or NOT!

Hey Ron,

15 yrs ago I began installing my system and after about 20 (1/2" black pipe) threaded joints I thought to check for leaks - every one leaked!! I tried everything - what finally worked - painful - was to re thread each fitting just one revolution with a die and/or tap. The 2 point of contact production threading dies left a linear stop line and that caused the leak. I ended up with over 200 threaded joints and with my 60 gal Ingersoll Rand and 6 female quick couplers it can go over a month and never kick on. Oh - my favorite sealant - Permetex Aviation #3. I built over 100 VW engines with it. I find that Fantastic/409 is a good leak detector - it will catch the smallest leaks. The smaller the leak, the finer the foaming. I should have tried your method - do what works!

Bill
 
your air systems are overkill

I have operated a woodworking shop for the past 18 years. All of the air systems are plumbed in 1/2" copper...same as household plumbing. Since the joints are all soldered there are no leaks except for the occasional one at the quick release ends that have to be changed from time to time.
 
PVC.......

.......is cheap and easy to use, will stand all the pressure your compressor can make. I ran mine from my outside air compressor (noisy) along the top of the walls and down on both sides of my hangar. Where they terminate at a quick-connect fitting, A tee in the line allows you to extend the line another foot to collect water with a 45 degree fitting and a drain valve. The quick connect is put in the tee. This setup gets very little water in the tools or your paint.

Regards,
 
I have PVC in my shop and never had a problem such as I hear some people have had. My system holds the pressure for several days without very much loss at all. All of my piping is sched 40 -1".
 
air systems overkill??

andrew phillips said:
I have operated a woodworking shop for the past 18 years. All of the air systems are plumbed in 1/2" copper...same as household plumbing. Since the joints are all soldered there are no leaks except for the occasional one at the quick release ends that have to be changed from time to time.
Click to expand...

Andrew, I'm not sure whose systems you are referring to here among the posts. I agree to the superiority of a soldered copper system, and had that when I owned property in the past. I rent now and the air system has to be of a more temporary nature. I also don't like black iron pipe as rust and scale have a way of finding a way around safety glasses at 90 psi. I'm now using poly tubing and rubber air hose, and I'm just stating that I have mostly given up on taped joints in favor of RTV. Just a tip I thought someone might find useful.
 
My PVC system failed after about 4 years. I think the key to it's survival is to not allow any oil to enter the system. Oil at the tool and not after the filter.

Soldiered copper pipe has served me well for the last 4 years now.
 
didn't mean to ruffle feathers!

I had visions of people installing air systems with pipe like that used for gas lines and having to have the ends threaded and buying bulky heavy fittings etc. Lots of easy options today including quick connects with plastic tube (check out topring) where the fittings are permanent but can be re-used later just by pulling them apart...does get costly though.
 
Every time this topic comes up it makes me cringe when I hear of people using PVC for air lines. I sure did my own "stress testing" of PVC with air as a kid. Just plain dangerous. I think soldered copper water pipe is the easiest thing to work with. And not too expensive either. When I did my last (current) setup, I showed Tanya how to do one joint, she said "cool", I handed her the torch, solder, wire brush, and flux and she did the rest. I measured and cut, she soldered on the joints, we secured the pipe to the wall with proper clamps, and had it all setup with takeoffs and drains in just a couple of hours. I'm preparing to setup a new shop for the next build and am going to do the same thing on a larger scale.
 
PVC, pro/con

PVC pipe will do the job, but it does have some drawbacks, as well as some pluses.

First off, it is very easy for almost anybody to do, no special tools needed. It is cheap to purchase, and there is an amazing selection of fittings.

You do need to use the schedule 40 pipe and fittings, use primer before gluing, and support the pipe more often that you would do with metal pipe. It is very easy to repair.

Main drawbacks are that it is easily damaged, is not tolerant of many chemicals, nor UV light. Dont ever use PVC where it is exposed to sunlight.

Unlike metal pipe, which will usually just split when it fails------at the pressure we are using, not pipe bombs------PVC will fragment it to shrapnel.

Which ever way you go, use common sense, and be safe.

P.S., I have PVC in my hanger, installed by the previous owner. I do not plan on replacing it.
 
Last edited:
Sched 40 1" is rated at 480 PSI, unless I'm missing something 125 psi is not going to hurt it at all. I agree in supporting it more often than copper, using a cleaner and a quality glue. I have been using PVC since 1980 in shops and never had an incident.;)
 
Last edited:
SCH 40

Hi all
Just add to what Mike Starkey said.
It take 24 hrs for glue to fully set up.

William
 
Thanks

William, thanks for adding that------just second nature to me, I didnt even think of mentioning it.

Hopefully your comment prevents someone from a bit of grief.
 
WOW!

I've been an engineer for 30 yrs and I always learn something in VAF forums. Yep - black pipe leaves chips so I do have to purge each outlet once a year. But it was cheap. I looked up the copper specs on copper.org - I didn't do my home work back then copper looks pretty good with the right solder, maybe 500 psi at 200 Deg F. PVC still bothers me - the rating is at room temperature. A hair dryer will heat to rubbery consistency. That can be as low as 200 deg F. (Not exact so lets not split hairs) The availability of schedule 80 PVC honestly has me thinking about it for future expansions. Cold temps is another issue. My pipe runs inside exterior and attic spaces in the garage and with -20 F temps it can get cold. I also run 175 psi from the 2 stage compressor. Lots of sandblasting in the driveway and blowing out the in-ground irrigation system means that I have a wide range of temps - copper looks better for me. Maybe more home work will move me to PVC. I am still cheap.
Bill

PS - http://www.engineeringtoolbox.com/thermoplastic-pipes-temperature-strength-d_794.html here is a link for getting strength vs temperature 130 deg F drops strength of regular PVC by 70% That's 144 psi for schedule 40 (down from 480). I'm a numbers and probability guy - I can argue wtih succcess, but I think I'll stick with metal.
 
Last edited:
You must log in or register to reply here.