[AT] Air lines for shop

[Stephen Offiler]

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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