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#16 HDWildBill OFFLINE  

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Posted August 10, 2012 - 02:06 PM

Thanks for all the input. Over the years I have seen other shops with PVC, I don't know if that was up to building code or not, but it seemed to work quite well. Both compressors are rated at 125 psi max but I will have to check what the kick in pressure for the smaller compressor is (I've had it for quite some time). The line pressure will probably be around 90-100 psi.

It will probably be a few more weeks before I do anything but I just wanted to get ya'll input into if it was possible. I'll post some pics when I get done. Thanks

#17 olcowhand ONLINE  

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Posted August 10, 2012 - 02:58 PM

My PVC air lines have been doing fine for so long I can't remember....15 years, maybe more!

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Posted August 10, 2012 - 04:04 PM

Thanks for that table, I'm old school too, but that looks very enticing compared to cutting threads on black pipe. I'm planning some changes in my shop and that would be a lot faster to extend than my black pipe. I notice those are ratings @73 F. What about twice that along my attic space? Does this degrade at the higher temps or over time? If not, why are all the commercial places I've seen go up around here are still using black pipe?


Building codes for commercial applications. It will not degrade if not in direct sunlight for years. I have a nursey with pvc irrigation that is 6 years old. Still intact.
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#19 Tennblue59 OFFLINE  

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Posted August 11, 2012 - 01:45 PM

Since I am in early install on this same issue, thought I would weigh in.

Have been running the shop on a small portable 3 hp compressor with 30 gllon tank. Finished rebuilt on my Standard American 5 hp 2 stage compressor and have it mounted on a 60 gallon tank, so plan to upgrade to the bigger setup. But also plan to be able to leave the smaller one on line if needed. Two tanks increase your air storage capacity - good for SHORT bursts beyond your compressor flow rate. As stated, as long as the pressure is about the same, works fine. Will put the smaller on into the pressure line via a flexible hose with shutoff, so I can pull it out of the system to use it portably.

As for the lines, I plan to go black iron. Course I can cheat and cut all the threads I need on the lathe.... I also frequent several model engine building and mechinist's forums, and everyone seems to go through this topic from time to time. A lot of people use the PVC without incident. But have also heard of a few catestrophic failures. Problem with pvc is it is brittle and becomes a grenade if it ever does fail, and is more susseptible to impact or bending damage. Iron has issues as well, but they are less safety issues.

FOR ME (YMMV...) the extra cost for the one time purchase of iron over pvc was worth the peace of mind and fit in my environment. But whatever works for you!
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#20 Toolpartzman OFFLINE  

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Posted September 13, 2012 - 03:45 AM

Thanks for all the input. Over the years I have seen other shops with PVC, I don't know if that was up to building code or not, but it seemed to work quite well. Both compressors are rated at 125 psi max but I will have to check what the kick in pressure for the smaller compressor is (I've had it for quite some time). The line pressure will probably be around 90-100 psi.

It will probably be a few more weeks before I do anything but I just wanted to get ya'll input into if it was possible. I'll post some pics when I get done. Thanks


As Brian & others have said, you will need to set kick-in pressure on BOTH pressure switches exactly the same or one will never fire. I don't know what motor HP you are working with, but some pressure switches can be used to start TWO motors if you can't get them to sync. ( i.e. 1 switch driving both pump motors) Many small compressor switches have so much slop (inaccuracy) that its impossible to get them firing together for any length of time.
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Posted September 13, 2012 - 07:50 AM

As Brian & others have said, you will need to set kick-in pressure on BOTH pressure switches exactly the same or one will never fire. I don't know what motor HP you are working with, but some pressure switches can be used to start TWO motors if you can't get them to sync. ( i.e. 1 switch driving both pump motors) Many small compressor switches have so much slop (inaccuracy) that its impossible to get them firing together for any length of time.


You could use the pressure switch to engage an contactor that is heavy enough to start two motors.
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#22 MH81 OFFLINE  

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Posted September 13, 2012 - 05:39 PM

Bill,
I know PVC has been used a lot over the years for air. (I have it myself) but the reason it's not "Approved" is PVC does eventually get brittle is the wide temp swings most buildings see coupled with petro (oil, gas, cleaners, etc) exposure. Eventually, you hope to only have a leak, not a pop.

There are several local guys recently who have used PEX for their lines. The stuff i saw had a burst rating of over 400 lbs for room temp and over 200lbs at 180 F. It also bends easier and shouldn't shatter if it ever develops a weak spot or gets hit.. The only negative I heard was that it tends to not let the heat out of the air, thus keeping the water in the air all the way to the tool. IDK if that's true, but it was mentioned, so I'm passing it on.

BTW, If you do go this way, use the stainless rings and plan on two per fitting. Better safe than sorry. :)
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#23 GTTinkerer OFFLINE  

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Posted September 13, 2012 - 06:03 PM

I installed schedule 80 pvc 10 years ago in my garage. No problems.


http://www.engineeri...ures-d_796.html


I also have been using 1" schedule 80 PVC in the garage since I built it in 1988. Never a problem BUT the pressure regulator is on the on the compressor before the PVC and is never set above 120 psi.. The compressor tops out a 175 psi but as far as I know that much pressure has never been applied to the tubing,
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#24 whst400 OFFLINE  

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Posted September 24, 2012 - 09:05 PM

Our PVC air lines passed all TEXAS state building codes in our plant and shop.

Must have been inspected by someone that doesn't know the NATIONAL code. PVC is illegal for any type of gas. Air is considered a gas. The pressure ratings printed on PVC are for water pressure. Water is virtually non compressable. That means that if a leak develops the pressure behind water immediately disipates, unlick compresses air which has to expand back to it's original, uncompressed colume before the pressure is gone.
Black pipe is the preferred way to go for air, but an easier, cheaper way to run air lines in a home shop is with jackhammer hose. It is similar to fire hose and can be easily moved as shop needs change.
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