On Wed, 10 Feb 2016 18:52:34 -0500, Frank "frank wrote:

Burning a piece can give you some idea. Polyethylene will smell waxy
but polyvinyl chloride will have an acrid smell due to presence of HCl
PVC is more readily attacked by solvents while PE is not. Put a piece
in acetone and see if it is attacked.

PEX is crosslinked polyethylene and I suppose above advice would not
differentiate between PE and PEX.

Thanks for the advice. One thing I never understood is the use of the
word "crosslinked". What exactly does that mean?

I'll have to try these suggestions. I do wonder what would happen if
this was PE, (Not PEX) and I was to install some of it as water pipe,
using regular PEX fittings and clamps? When weather allows, I want to
run some water lines in my barn and would like to use what I have. This
will not be left under pressure, since it will just be connected to the
barn hydrant with a piece of garden hose, when needed to fill stock
tanks. Once the tanks are filled, the water hose will be disconnected,
so all water can drain out (to prevent freezing) in cold weather. I
intend to run this so all pipe slopes toward the hydrant, so it drains
out as soon as I disconnect that short piece of hose.

But if it's NOT PEX, then I suppose I'd be better using regular hose
clamps and barbed fittings. That's why I am trying to determine what I
have.