PEX-a

Is made using the Engel method. The Engel method is a hot cross-linking process, meaning the actual cross-linking takes place during the extrusion process when the base polyethylene is above its crystal melting temperature. The Engel method provides more precise control over the degree, consistency and uniformity of cross-linking. This means the tubing is evenly cross-linked, with no weak links within its molecular chains.

This is the most flexible type of PEX pipe.

Compatible connection types with PEX-a are: ASTM F1807, F1960, F2080 & F2159

PEX-b

Is made using the Silane (or moisture cure) method. This method performs the crosslinking with a chemical agent where the process is accelerated using heat and moisture. This chemical crosslinking creates a slightly stiffer final product than PEX-a.

Typically, ASTM F1807 connection types are used with PEX-b.

PEX-c

Is manufactured using the irradiation method of cross-linking. The Irradiation method the pipe is extruded first and then sent through an accelerator to complete the cross-linking process. The Irradiation method provides more precise control over the degree, consistency and uniformity of cross-linking. This means the tubing is evenly cross-linked, with no weak links within its molecular chains.

Stiffer than PEX-a but, less than that of PEX-b

Compatible connection types with PEX-c are: ASTM F1807, F1960, F2080 & F2159

PEX-AL-PEX

Is a multi-layer pipe made of two PEX layers with a continually laser welded aluminum layer in the center. The aluminum layer is bonded to the PEX layers with a special adhesive material. This combination of special raw materials of very high molecular weight result in a special pipe having several important qualities; corrosion resistance, excellent mechanical resistance, lower expansion rate, unique chemical resistance, very low friction coefficient, no oxygen permeation, and high working pressure and temperature

Flexible and it will keep its shape.