| PEX Pipe Types |
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Available Types of PEX PipePEX (Cross-linked polyethylene) is a form of polyethylene with cross-links. Polyethylene is a polymer- a well known example being plastic. Cross-links are bonds that link one polymer chain to another. Cross-linking is accomplished during or after the extrusion of the tubing. European standards refer to three methods of producing PEX pipes, namely PEX-A, PEX-B and PEX-C. Their names do not relate to any type of rating system as all the PEX piping products perform similarly - their name refers to the method of producing PEX piping. PEX-A - The "Engel" or peroxide method is where peroxide is added to the base resin and through a combination of pressure and high temperature the cross-linking takes place as the pipe is extruded. PEX-B - The "Silane" method of PEX production is where cross-linking is performed in a secondary post-extrusion process. It involves grafting a reactive silane molecule to the backbone of the polyethylene. The tubing is produced by blending this grafted compound with a catalyst. After extrusion the tubing is exposed to either steam or hot water to induce the final cross-linking reaction in the tubing. PEX-C - Electron Beam crosslinking 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 chains to bond or link to the open carbon sites. PEX is formed into tubing which can be used for hydronic floor heating and domestic water piping. PEX is normally available in 16mm, 20mm, 25mm, 32mm, 40mm, 50mm and 63mm sizes. |