PEX Tubing Manufacturing Methods
There are three
primary methods for producing PEX tubing.
1. The "Engel" or peroxide method of PEX tubing
production employs a special
extruder with a plunger action where peroxide is added to the
base resin and through a combination of pressure and high
temperature the cross-linking takes place as the tubing is
produced.
2. The "Silane" method of PEX production involves
grafting a reactive silane molecule to the backbone of the
polyethylene. The PEX tubing is produced by blending this grafted
compound with a catalyst which can be done using either the
Sioplas method or by using a special extruder it can be done
using the Monosil method. After extrusion the PEX tubing is exposed
to either steam or hot water to induce the final cross-linking
reaction in the tubing.
3. Electron Beam crosslinking method of PEX tubing
production takes place when very high
energy radiation is used to initiate molecular cross-linking in
high density polyethylene. This product is extruded like normal
HDPE then taken to an E-beam facility and routed under a beam or
ray in the accelerator where it is dosed with a specific amount
of radiation to release the hydrogen atoms and cause polymer
cahins to bond or link to the open carbon sites.
In European standards these three methods are referred to as
PEX-A, PEX-B and PEX-C, respectively and are not related to any
type of rating system. All the resulting PEX tubing products
perform similarly and are rated for performance by the ASTM, NSF
and CSA standards for which they are tested and certified. The
listings and certifications met by each PEX product are printed on
the printline of the PEX tubing itself to ensure the product is used
in the proper applications it was designed for. |
 |
