As plumbing professionals explore flexible alternatives to copper, CPVC, and other rigid pipe types, understanding the properties, features and benefits of PEX tubing has become more important than ever.
Compared to rigid pipe types, PEX, or cross-linked polyethylene, requires fewer fittings and its flexibility allows it to bend easily around corners and in small spaces. Additionally, PEX withstands freezing, corrosion, and other damage that rigid pipe types can be susceptible to. If you’re planning to use PEX and curious about which will work best for your needs, read on for information that will shed light on the most appropriate PEX type for you.
Many people in the field ask about what PEX types, A, B and C actually mean. Contrary to popular belief, PEX types “A,” “B,” and “C” are not indicative of quality. These letters are only used to identify the manufacturing process and do not reflect performance of the product. It should be noted that all PEX complies with ASTM F876 and is designed for potable water distribution systems (NSF/ANSI/CAN 61 compliant).
PEX-a is manufactured using the peroxide method, also known as the “Engel” method, where organic peroxides are heated, generating free radicals that splice PEX chains together during the extrusion process. PEX-b is manufactured by using the moisture-cure or “Silane” method. For this crosslinking method, PEX tubing is exposed to hot water or steam after extrusion. Note that SharkBite PEX is classified as PEX-b. PEX-c is manufactured via the Electronic Radiation method, in which crosslinking of molecules is done after extrusion by exposing the pipe to an electron beam.
Key differentiators regarding PEX quality are chlorine resistance and UV resistance. All SharkBite PEX that is marked with Material Designation code “PEX 5306” indicates continuous recirculation listing and six-month UV protection. PEX 5306 rating also makes SharkBite PEX the highest-rated in the industry.
Get more information on SharkBite PEX and accessories, and check out our FAQs to discover some of the common questions we receive from the field.
*Material Designation code must be marked on the tubing. The three components of the ASTM F876 has a PEX designation code are:
- Digit 1 = Chlorine Resistance rating
- Digit 2 = UV Resistance rating
- Digits 3 & 4 = Hydrostatic Design Stress (HDS)
- By Code you are required to have PEX1106 for traditional domestic hot water systems
- Except for California (PEX5106)