home garage compressor: how many CFMs?

[Casting Fool]

From: "Brett Dikeman" <brett at cloud9.net>
> One note here- I've read that PVC has an incredibly failure rate...

Go with a belt-driven compressor.  The difference in noise will save your
marriage.

On PVC pipe, DON'T!  When it goes BOOM, you and your family will be ducking
razor sharp shrapnel that's moving at "relativistic speeds".  PVC pipe is
rated for "wet" (liquid) pressure, not air pressure.  Think about it.  Water
is terribly difficult to compress.  Just a little is needed to reach a rated
pressure.

But air is extremely compressible.  It'll take a LOT of air to reach the
same pressure as you would get with using water.  If a water-filled PVC pipe
pops, the pressure drops almost immediately because the water can only
expand a little.

When an air-filled PVC pipe POPS, you can be killed or seriously maimed.
There's a lot more air to expand than there was water in the last example,
and those broken bits of PVC will blur across the room.

I've experienced this personally.  I helped to design and build a water
treatment plant.  Someone turned on the power while I was leaning over one
of the pH treatment tanks and both wells came on-line, but the safeties
hadn't been installed on the wellheads yet and the main valve was off.

The rush of air from one of the wells shattered 2" schedule 80 PVC pipe and
blasted a valve assembly across the building into a cinder block wall 8'
away.  It left gouges in the block.

It missed my head by inches as it left the installation point.  I didn't
even have time to realize that I was in danger.  I could have been killed
instantly by the impact.

The best route is to use either properly rated copper, steel, or carefully
routed compressor hose.  Keeping the line inside where it's climate
controlled and inclining the line so that the moisture will gather and run
toward one end will help to reduce the moisture problem, as will having a
water trap at both ends of the line, one at the compressor and another at
the end point where you hook in your flex line and tools.  Also remember to
drain the compressor tank occasionally.

I know that I'm mostly here because I manufacture repro parts, but I do use
an air compressor daily in my casting work, as well as a vacuum pump and
vacuum chamber.  Along with my experience in water treatment, I understand a
little bit about what's safe and what's not with compressing air and moving
it from one place to another.

Be safe, put out the extra bucks for copper, steel, or regular compressor
hose if you need to extend the line away from the compressor (I use the
last, as I can't install anything permanent in my rental unit.)

TTFN - Mike Jackson
Casting Fool & Son
Augusta, GA  USA
http://www.cfnson.com