GUIDE TO CHLORINE RESISTANCE RATINGS OF PEX PIPES AND TUBING FOR POTABLE WATER APPLICATIONS
|Publication Date:||1 November 2018|
The intent of this Technical Note is to give guidance to plumbing system designers, installers and specifiers for understanding chlorine resistance ratings as applied to crosslinked polyethylene (PEX) pipes and tubing for potable water applications, and to describe the effects of using PEX pipes and tubing in operating conditions beyond these published ratings.
This Technical Note is provided to explain how PEX pipe conforming to standard ASTM F27881 and PEX tubing conforming to standards ASTM F8762 and CSA B137.53 may be used safely in potable hot- and cold-water distribution systems, within the specific limits discussed within this document. This Technical Note is also intended to clarify that the typical hydrostatic pressure and temperature ratings for PEX tubing (e.g. 160 psi @ 73°F, 100 psi @ 180°F) are not to be confused with the operating conditions which are anticipated in hot chlorinated potable water systems.
As a Guide for users of PEX systems, this document explains ASTM Test Method F2023 in detail, and identifies the four categories of chlorine resistance ratings which are defined within product standards ASTM F876, ASTM F2788, and CSA B137.5.
The Technical Note also differentiates between residential and commercial plumbing systems and explains that continuous recirculation of hot chlorinated water through PEX pipe or tubing at commercial temperatures above 140°F (60°C) is beyond the intended application of the standard chlorine ratings as defined in those standards listed above.
However, the fact that the chlorine ratings outlined in those standards do not explicitly cover commercial systems operating above 140°F should not be construed as an indication that PEX is never suitable for those applications. Some PEX products are specifically designed to meet the rigorous requirements of systems with either continuous or intermittent recirculation of water at temperatures exceeding 140°F.
Note 1: For PEX materials, "tubing" refers to products whereby the actual outside diameter (OD) is 1/8 inch larger than the nominal size, and is described as copper tube size (CTS). Product standards ASTM F876 and CSA B137.5 apply to PEX tubing. "Pipe" refers to products whereby the actual OD matches that of steel pipe of the same nominal size and is described as iron pipe size (IPS), or products where the actual OD matches the nominal size. Product standard ASTM F2788 applies to PEX pipe. The terms "pipe" and "piping", as well as "tube" and "tubing", are used interchangeably in this document.
Note 2: See PPI TN-52 GUIDE TO HIGH-TEMPERATURE APPLICATIONS OF NONPOTABLE PEX PIPE AND TUBING SYSTEMS for explanation of hydrostatic pressure ratings and considerations for use in non-chlorinated water systems operating at temperatures above 180°F (82°C).
1 ASTM F2788 Standard Specification for Metric and Inch-sized Crosslinked Polyethylene (PEX) Pipe
2 ASTM F876 Standard Specification for Crosslinked Polyethylene Tubing
3 CSA B137.5 Crosslinked Polyethylene (PEX) Tubing Systems for Pressure Applications