ASTM F876, Standard Specification for Crosslinked Polyethylene (PEX) Tubing, has recently been updated (ASTM F876-02) to include a requirement for the oxidative stability in potable chlorinated water applications under Section 7.11 of the standard.
Test method F2023-03, Standard Test Method for Evaluating the Oxidative Resistance of Crosslinked Polyethylene (PEX) Tubing and Systems to Hot Chlorinated Water, lists the requirements and test methods for evaluating PEX tubing in long-term contact with chlorinated water. The newly revised standard requires all PEX pipes used in potable water to be evaluated against the ASTM F2023 test method and have a minimum extrapolated test lifetime of 50 years at the end use conditions of 25% of the time at 140°F and 75% at 23°F, with 80 psig constant internal gauge pressure.
The conditions described in Test Method F2023, Section 13.3, apply only to the intermittent service (traditional domestic). Currently, this method does not validate the use of PEX tubing in continuous recirculation applications. Manufacturers of PEX tubing should be very cautious about applying marking such as "ASTM F876 and F2023-CL-R" marks until the continuous recirculation application is incorporated into the F2023 test method.
This addition to ASTM F876 mandates that all current and proposed PEX tubing for the NSF/ANSI Standard 14 Potable Water Listing must conform to this new requirement.
To verify whether a PEX Pipe meets this requirement visit NSF International website at www.nsf.org.