[AT] Pressure drop?

[Gene Waugh Elgin, Illinois USA]

What has interested me the most in this thread is the use of 
PEX--farmer, someone asked what fittings you will be using?  I think 
they make barbed fittings that use a compressed band to hold them 
together, and perhaps they have a threaded compression sort, as was used 
with the old Quest.  (Qest?, memory is failing) piping, which turned out 
to burn many, many people.  Biggest problem was the fittings, especially 
aluminum compression rings for the crimped fittings.  Especially on the 
hot side, the aluminum would work-harden and eventually let go.  There 
were also rings of a copper alloy, and I don't think they were nearly 
the problem.  Sploosh!  We would test it hydraulically to about 160 psi.

Using PEX for air doesn't bother me anywhere near as much as PVC---at 
least you won't have shards flying around, just a big ol whipping snake 
perhaps!  Again, I am curious as to the fittings used.  Unless you 
simply have the 1/2" lying around and want to use it, I sure think I 
would go with at least 3/4" for such a long run.  Personal opinion.


/Gene
Gene Waugh
Elgin, Illinois USA/


Francis Robinson wrote:
> 	OK, who knows compressed air pressure drop off of the top of your head? 
> :-)
> 	I am going to run a compressed air line from one shop to the other. It 
> will run inside of an underground conduit in 1/2" PEX tubing. It will 
> basically have one fitting (full 1/2") at each end of the run. The run will 
> be 250' long with no fittings at all in the line itself. If I have 125 PSI 
> at one end what kind of drop can I expect at the other end? What would it 
> be at 800'?
> 	BTW, PEX is rated and recommended for compressed air. I was reading the 
> print on the pipe today and for water what I have on hand at the moment is 
> rated at 100 PSI at 180 degrees F. It will not get hard and brittle and it 
> will not shatter on impact. It is cross linked polyethylene and is not 
> affected by oil.
> 	I am really in love with this stuff for water plumbing.
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> "farmer"
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