What is PEX?
An Uponor plumbing system features Engel-method crosslinked polyethylene (PEX) tubing. This is a flexible plastic tubing product that has been used for more than 35 years in radiant floor heating, plumbing and fire safety systems.
PEX is classified into three categories: • PEX-a (Engel or peroxide method) • PEX-b (Silane method) • PEX-c (Electron beam or radiation method)
The PEX tubing industry considers Engel-method PEX-a tubing superior because the crosslinking is done during the manufacturing process when polyethylene is in its amorphic state (above the crystalline melting point). Because of this, the degree of crosslinking reaches around 85%, resulting in a more uniform product with no weak links in the molecular chain.
The properties in PEX-a tubing make it the most flexible PEX on the market, allowing for the tightest bend radius available — as little as 3½” for ½” tubing. Its flexibility also greatly reduces the instance of kinked tubing. However, because of the thermal memory of PEX-a, if a kink does occur, a simple shot from a heat gun returns the tubing to its original shape.
The Unique ProPEX® Connection
The shape memory of PEX-a tubing allows it to expand and then shrink back to normal size. This allows for the use of Uponor’s unique ProPEX® expansion fittings, which capitalize on the shape memory of PEX-a to create strong, durable and reliable connections without the use of dangerous torches, glues or solvents.
