air lines for my bus garage

[David Anderson]

I am getting close to actually building a bus garage/woodshop for the Eagle and my other Tim the Toolman endeavors.  I was wondering about running some 1/2" plastic lines under the slab and stub up in various places in the shop for compressed air.  My fear is too much moisture accumulating in the lines and going through my tools.   When I built my house 15 years ago I laid about 80' of pvc line under my slab and stubbed up in a couple of places.  It works great but I do get annoying moisture out the blow gun. 

Should I forgo this and just run everything overhead?  Overhead allows placement of moisture trap drip legs.   Underground doesn't.  Any ideas of suggestions?

David

[desi arnaz]

run a 2 inch grey PVC under the floor and then snake a hose inside that,then you don't have to worry about the PVC breaking due to high pressure.

[RJ]

David -

Years ago I ran air lines in my garage, even tho I was working on Corvairs at the time.

I ran all mine overhead, with moisture filters, thus never any gunk in the tools.

Of course the slab was already there when I started. . . but I still would have kept the air lines above ground.

If anything, put hydronic heat in the floor!

FWIW & HTH. . .

[bevans6]

Well. you probably know that PVC isn't rated for air unless it's buried.  The stories about exploding PCV are legendary...

Black pipe up high and downward stubs with drains is classic old-school.  I don't know why you couldn't use copper with soldered joints.  Thinking out loud, I don't know why you couldn't use 1/2" flex air line from a bus!

Brian

[luvrbus]

Why isn't PVC not rated for air unless buried keep the temp down it does good 600 psi is 600 psi regardless only the temperature will affect the bursting pressure 1/2 in sch 40 pvc is 600 lbs @ 73 degrees the 1/2 cpvc is 100 psi at 180 degrees anything below 180 or 73 degrees will increase the psi ratings


good luck

[bevans6]

Apparently it can shatter, explode with shards/shrapnel and otherwise become objectionable.  I think there is also an issue with flame resistance/melting.

Anyway - http://www.osha.gov/dts/hib/hib_data/hib19880520.html

With that said, I wouldn't be at all surprised if there are modern "PVC equivalent" products that can be used.  I was just taught that plain old Home Despot PVC like you buy for your water drains and supplies wasn't good to use.

Brian

[luvrbus]

Times and methods of manufacturing PVC since 1972 when that was written Brian, only a Canadian would link us to a OSHA site lol seriously they are using the stuff about for everything now that and poly pipe

good luck

[Len Silva]

I found that same OSHA link (damn gummint regulators), and within that link is this explanation:

Colonial Engineering Inc.
Thermoplastic Piping Systems

To Whom It May Concern:

From time to time, I receive inquiries as to the suitability of using PVC pipe land fittings in compressed gas piping systems. While the benefits of use may be enticing, it is a very dangerous and, in some states, illegal thing to do. For example, MIOSHA (Michigan's branch of OSHA) prohibits the use of PVC plastic in compressed gas systems unless properly encased in steel, cement, or some other approved material. Please check your local and state regulations.

The main problem with using PVC pipe and fittings for compressed gas is not that it spontaneously explodes but that PVC is a brittle material that can be broken or shattered with external force unless properly protected. Compressed gasses can be best described as being analogous to a coiled spring. When a PVC pipe or fitting fails when under stress from compressed gas it literally explodes like a bomb, sending shards of plastic flying several feet in all directions. Liquids, on the other hand, being compressed by only 1/10th of 1% contain very little stored energy. When pressurized systems with liquids fail, the energy is dissipated very quickly, thereby creating a much lower potential for hazard.

Colonial Engineering does not recommend the use of PVC plastic pipe fittings in compressed gas service.

If you have further questions regarding this matter please feel free to contact me directly.

Sincerely,

Jack Roach

That said, I knowingly used PVC in my shop, limited to 125 psi and had no problem.  I ran the first 8 feet or so from the compressor in steel pipe in order to give the air a chance to cool a bit before hitting the plastic pipe.

[Len Silva]

Times and methods of manufacturing PVC since 1972 when that was written Brian, only a Canadian would link us to a OSHA site lol seriously they are using the stuff about for everything now that and poly pipe

good luck

I first became aware of the issue when I was doing my shop.  Walking through the Home Depot plumbing section and the boxes of fittings are clearly labeled "not for compressed air".

Pipes carrying compressed air will explode and shatter where the same pipes with water will just split and leak.

[bevans6]

Well it was written in 1988, not 1972 when the pipe apparently became available, I guess implying that the stuff was OK for 16 years     Some one probably got killed or maimed by an explosion, that's how these things usually work...   

I do think that there are probably modern equivalents that install and look similar to PVC that are OK.  I wouldn't be at all surprised if PEX or a PEX equivalent wasn't rated for low pressure gas.  I shall look and see!

Brian

[luvrbus]

You are seeing SDR21 fittings in those places Len huge difference in PVC fittings I see people use waste pipe fitting on pressure pipe for  water they blow off or break they look the same but the collar part will be longer I use sch 80 fitting on everything it cost a little more most people, never read the glue can either tons of different glue for different sizes and PVC pipe types

.David can use poly pipe if he chooses it made from 1/2 inch to 48 inch they are using poly for high pressure gas lines and gravity flow sewer line it is fused together instead of glue.

I am not afraid of PVC I wouldn't use sch 20 or irrigation PVC or the fittings  

[bevans6]

And here it is:  http://www.ipexamerica.com/Content/Products/Product.aspx?MarketSegmentId=1&SubMarketId=9&ProductId=93

It's the PEX with the aluminium layer.  Sold as Duratec Airline.

I just use great heaping rolls of 3/8" or 1/2" air hose.  Simplest, dumbest, most labour intensive solution, but that is so me...

Brian

[luvrbus]

Brain, I see that place sells ABS for air lines also I don't have PVC I have 1/2 steel but with todays prices on steel pipe PVC would be my choice fwiw

good luck

[Len Silva]

You are seeing SDR21 fittings in those places Len huge difference in PVC fittings I see people use waste pipe fitting on pressure pipe for  water they blow off or break they look the same but the collar part will be longer I use sch 80 fitting on everything it cost a little more most people, never read the glue can either tons of different glue for different sizes and PVC pipe types

.David can use poly pipe if he chooses it made from 1/2 inch to 48 inch they are using poly for high pressure gas lines and gravity flow sewer line it is fused together instead of glue.

I am not afraid of PVC I wouldn't use sch 20 or irrigation PVC or the fittings  

Not to be overly argumentative but I was clearly looking at Schedule 40 PVC glue in fittings, not DWV or SDR21.

I chose to use them anyway in spite of the warnings but it was an informed choice.  That's all we are looking for here.

[robertglines1]

I have pvc in shop for 20 yrs.  that said    put a piece in freezer for couple hrs then drop it on the floor.   Hasn't been a problem for me. My air lines are fastened down. rubber from outlets.    Bob