[AT] Air lines for shop

Mon Sep 13 09:01:41 PDT 2021

Water is certainly a problem!  We get humid here (southern New England)
too.  At work, our 1980's vintage 25HP Ingersoll-Rand seized up this past
spring, forcing us to the backup 1960's vintage 15HP and starting a 6-month
long odyssey to find a replacement.  Somehow Covid affected the compressor
industry, but I digress.  I needed to throw together a satellite system to
keep my 5 CNC machines running independent of the anemic, worn-out 15HP
backup.  I put in a typical 5HP/80-gallon vertical, plumbed with 1/2"
300-psi rubber lines from McMaster-Carr.  Added a chiller.  Added a
coalescing filter at the compressor, and serviced or replaced the
coalescing filter-regulators at each machine.  I get about a gallon or so
out of the system every morning in the humid months.  I didn't use any
copper because the whole thing was thrown together intended to be rather
temporary, but Spencer is absolutely correct that copper plumbing will help
cool and condense moisture better than black iron.  I would slope AWAY from
the tank and add vertical drops with valves at the bottom for draining.
Sloping toward the tank seems like it could work to some degree, but it
also seems that airflow might tend to push the moisture upslope.

SO

On Mon, Sep 13, 2021 at 11:19 AM Spencer Yost <spencer at rdfarms.com> wrote:

> 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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