PEX
is an acronym for cross-linked polyethylene. The "PE" refers to the raw
material used to make PEX (Polyethylene), and the "X" refers to the cross-linking
of the polyethylene across its molecular chains. The molecular chains are
linked into a three-dimensional network that makes PEX remarkably durable
within a wide range of temperatures, pressures and chemicals.
Flexible, installed with fewer fittings than rigid plumbing
systems. A good choice for re-piping and for new homes. Works well for
corrosive water conditions. It can stretch to accommodate the expansion
of freezing water and then return to its original size when water thaws.
Although it is highly freeze-resistant, no material is freeze-break proof.