[AT] Air lines for shop
Spencer Yost
spencer at rdfarms.com
Mon Sep 13 08:19:06 PDT 2021
One of the reasons I have been thinking copper is because here in the
humid south, water in air lines is a problem. You can not paint without
a desiccant filter for example. Nothing worse than seeing water droplets
coming out with your paint (been there done that). One benefit I
thought copper would have would be to condense water quickly and
earlier in the run; therefore water vapor would be less of an issue at
the tool end(assuming I slant the lines to run back towards the
compressor) and my tool-end water filters wouldn't fill up so fast.
Anyone with experience with copper find this to be true?
Also, copper is less than $1 per foot more expensive(3.46/ft vs 2.69/ft)
so for a run that will be less than 100' worth of pipe so I decided to
not sweat (excuse the pun) the cost factor between black pipe and copper
and just go on the merits.
While continuing to look around at various options and along the way I
saw 1-1/2" black pipe at Lowes with an oddly specific PSI rating:
231PSI I'm beginning to think Brice might be right and they are using
steam rating....
Spencer
On 9/13/21 9:55 AM, Stephen Offiler wrote:
> Brice reminded me of something. Now, it's been a while since I've put
> much thought into Schedule rating of pipe. Reviewing, the basic
> definition is: Schedule = Pressure/Stress. Example: Schedule 40
> pipe at 1200 psi would have stress of 30 ksi developed in the walls.
> That's why wall thickness increases with pipe diameter - larger
> diameter means larger internal surface area means higher force for a
> given pressure, so wall thickness is increased to fight the higher
> forces and keep stress in the wall constant. I pick the example
> above because Schedule 40 Class A pipe has a yield stress rating of 30
> ksi. (There is also a Class B which is somewhat stronger). At 175
> psi your factor of safety is almost 7, which is quite large. I'd
> sleep well with this number as small as 4 - in other words, 300psi.
> Of course there's additional considerations for the fittings and
> whatnot, but as long as it's Schedule 40, there's really nothing to
> worry about.
>
> That stuff at Lowe's claiming 150 psi.... I don't believe it. The
> people writing up the specs on their website are probably minimum-wage
> drones. I would get ahold of a chart showing wall thickness vs pipe
> diameter and measure the wall thickness right there in the store (yeah
> I do tend to travel with a caliper in my bag most of the time).
> Dimensions alone would confirm if this "150 psi" stuff is actually
> Schedule 40.
>
> I know you don't really want to use black iron pipe but I like I said
> Brice sort of reminded me of how all this pressure rating stuff
> works. Of all the options, black pipe is certainly the most
> old-school, antique-tractor appropriate. I'm not against the modern
> materials and I would also seriously consider Pex, but not PVC. I can
> solder copper way faster than I can screw together black pipe but
> copper is pretty darn pricey these days. In my own shop, the answer
> is: rubber hose. I've never graduated past the portable compressor
> to something big and stationary that lends itself to permanent plumbing.
>
> SO
>
>
>
>
>
>
> On Sat, Sep 11, 2021 at 11:43 AM Brice Adams <brice.adams at gmail.com>
> wrote:
>
> Spencer,
> Something tweaked my memory from plumbing the Huber about
> different pressure ratings for steam, air, and fluids with
> schedule 40 and 80 pipe. The 150 psi may be the steam rating and
> the air rating is 34 to 6 times higher.
> Brice
>
> On Sat, Sep 11, 2021 at 8:21 AM Ken Knierim
> <ken.knierim at gmail.com> wrote:
>
> Go copper if you're comfortable with sweating it together. I
> did that after trying PVC for awhile. Got some AZ sun on the
> PVC and it blew out a couple times with sharp little shards
> flying around (doesn't survive impact damage well). I like the
> sound of PEX but again, sunlight is abundant here.
> My $0.02
> Ken in AZ
>
> On Fri, Sep 10, 2021 at 6:43 PM Spencer Yost
> <spencer at rdfarms.com> wrote:
>
> So I’m going to be making three new pipe runs from my air
> compressor. Previously I’ve just relied on hoses since the
> 50 foot hose will reach everywhere in my shop.
>
> It will consist of one long “trunk” run that will be
> nearly 40 feet, and then a few stub runs of anywhere from
> 5’ to 15’
>
> I was thinking about black pipe as that’s what I have used
> before. But I had no idea the common, affordable black
> pipe you find in hardware stores is only good to 150 psi.
> My compressor is two stage and is 175 psi:
>
> 3/4-in x 3-ft 150-PSI Black Iron Pipe
> https://www.lowes.com/pd/Southland-Pipe-3-4-in-x-3-ft-150-PSI-Black-Iron-Pipe/3371442
>
> I guess I’m thinking about biting the bullet and going
> copper. I’d like to go with some of those really neat new
> aluminum systems but I could never afford that.
>
> What are y’all think about copper? I know 3/4” copper is
> good to about 1000 psi. It eliminates the rust problem
> that eventually befalls all black steel pipe systems;
> which is kind of a plus. As far as installation, I solder
> better than I cut threads :-)
>
>
>
> Spencer
>
>
> Sent from my iPhone
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--
Spencer Yost
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