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Polyethylene Tubing Systems

ASTM International Committee F17 on Plastic Piping Systems is currently developing a proposed standard that will address the use of crosslinked polyethylene (PEX) tubing used in hydronic heating/cooling systems. WK38788, Specification for Crosslinked Polyethylene (PEX) OD Controlled Tubing for Hydronic Heating/Cooling Systems, is under the jurisdiction of Subcommittee F17.26 on Olefin Based Pipe.

Gary Morgan, industry liaison manager, Viega LLC, and an F17 member, notes that the piping covered by WK38788 is used for a variety of applications, including radiant floor heating/cooling, snow melting, turf warming, geothermal heat pump systems and solar heating. WK38788 will be used by design engineers, specifiers, residential and commercial contractors, code officials and building inspectors.

Today the hydronic industry predominantly specified PEX products defined by ASTM F876, Specification for Crosslinked Polyethylene (PEX) Tubing, and F877, Specification for Crosslinked (PEX) Hot- and Cold-Water Distribution Systems. The creation of a new hydronic tubing system standard will allow the industry to add the applicable testing and construction allowances without being limited to the otherwise constraining dimensional and drinking water conformance limitations of the present standards.

The key focus of the proposed new standard will be to establish testing and performance requirements for limiting oxygen permeation into the hydronic fluid, which, if left unchecked, can lead to rapid corrosion of ferrous components within the system.

“In the model code arena, there has been recent work to develop new codes that specifically address the performance needs of hydronic heating/cooling and geothermal systems,” Morgan says. One of the goals of F17.26 is to have WK38788, once it has been approved, recognized in the hydronic model code being compiled by the International Association of Plumbing and Mechanical Officials.

Interested parties are invited to join in the development of WK38788. F17.26 is seeking input from laboratories that test for gaseous permeation of membranes and films as well as the advice of manufacturers who make barrier polymer compounds such as ethylene vinyl alcohol copolymer (EVOH).

CONTACT Technical Information: Gary Morgan, Viega LLC • Wichita, Kan. • Phone: 620-480-1222 | ASTM Staff: Robert Morgan • Phone: 610-832-9732 | Upcoming Meeting: Nov. 11-14 • November Committee Week • Jacksonville, Fla.

Commercial radiant floor heating/cooling installation

This article appears in the issue of Standardization News.