SUM 2018

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Page 18 of 38

Here's what you need to know B Y A A R O N S T O T K O M ore than 17 billion feet of PEX piping has been installed worldwide. That's enough to stretch to the moon and back almost seven times. In recent years, it has increasingly been installed in commer - cial hydronic applications. Although thoroughly tested and proven, PEX is still sometimes mis - understood. Many wonder if a plastic pipe can really compete with, let alone outperform, metallic pipe. Below are answers to common questions a commercial installer or specifying engineer may have about the material. In doing so, it explains why PEX is the right choice for hydronic distribution piping applications. ALL PEX IS NOT THE SAME Professional PEX products fall into three categories: PEX-a, PEX-b and PEX-c. Of those three, PEX-a, manufac - tured using the Engel Method, has the highest degree of consistent crosslink - ing — at 80 percent. This produces a pipe that is more flexible and more du - rable with thermal and elastic memory properties. UNDERSTANDING THERMAL AND ELASTIC MEMORY Thermal memory is the ability to repair accidental kinks in the PEX-a pip - ing with a controlled heating source, such as a heat gun. The controlled heat quickly eliminates the kink in minutes, while the pipe is restored to its original durability. Elastic memory refers specifically to how PEX-a piping will quickly return to its original dimensions after expansion. This allows the use of the exceptionally strong, ASTM F1960 fitting connection. In creating a PEX-a connection, the installer uses a specially made expan - sion tool to enlarge the diameter of the pipe, so that a fitting with a slightly larger internal diameter can be inserted. The pipe quickly compresses over the fitting, creating a durable connection that actually strengthens over time. Just as important: Because the fitting diameter is a bit larger than the pipe diameter, "dry-fit" pipe connections are physically impossible. This eliminates the problem when an installer neglects to solder or glue a fitting in a copper or CPVC system, resulting in costly leaks inside the walls of a completed project. An ASTM F1960 fitting requires the connection be fully made, permitting quick visual confirmation. THE DIFFERENCE WITH EXPANSION FITTINGS Unlike with metallic pipe, an expan- sion fitting is actually the strongest part of a PEX-a system. It will not leak. In fact, pull testing shows that even 3,000 pounds of force with over 13 inches of displacement does not compromise the integrity of the ASTM F1960 PEX-a con - nection. In all likelihood, there would be a catastrophic failure of the building structure before enough force is applied to break that connection. USING HANGERS AND SUPPORTS PEX-a pipe can be hung at similar intervals as metallic pipe. It's true that other plastic piping systems typically require supports every 32 inches. Some manufacturers, however, offer PEX-a pipe supports — a galvanized steel chan - nel that provides continuous support in suspended-piping applications. This support allows PEX-a to behave just like a metallic piping system in many ways, including hanger spacing: ½-inch and ¾-inch PEX-a pipe can be hung at 6 foot intervals; 1-inch through 3-inch pipe, at 8 foot intervals. ADDRESSING EXPANSION AND CONTRACTION The PEX-a pipe support controls the natural expansion and contraction that occurs as the piping heats and cools. Used in conjunction with manufacturer- recommended installation practices, the pipe support allows PEX-a to undergo an expansion rate equal to or, in some cases, less than that of copper. TEMPERATURE AND PRESSURE CONSIDERATIONS PEX-a is rated for continuous operation at 200 F at 80 psi. Any hydronic ap - plication with water temperatures at or below this value is perfectly applicable for the product. FIRE-RESISTANT CONSTRUCTION RATINGS PEX-a is ASTM E84-rated for flame and smoke resistance inside a non-ducted, return-air plenum. This also applies to firestopping. For more information regarding these listings, please contact the manufacturer. CODES AND STANDARDS COMPLIANCE PEX-a is compliant with all codes and standards that pertain to it, whether in the International family (IBC, IRC, IMC, IPC) or the Uniform family (UMC, UPC, CPC) of U.S. codes. Aaron Stotko is a commercial segment manager at Uponor. He can be reached at aaron.stotko@uponor.com. Considering PEX in Hydronic Applications? 1. With its corrosion-resistant nature, PEX piping is ideal for piping to terminal units such as variable air volume systems. 2. With the use of PEX pipe support steel channels, the pipe can offer the same straight aesthetics as metallic systems with similar hanger spacing. 2 1 BOTTOM-LINE BENEFITS OF CHOOSING PEX-A > PEX-a can be run in continuous coils, up to 1,000 feet in length, resulting in fewer required fittings. > Its thermal memory allows fast and easy kink repairs with a simple shot of heat from a heat gun, minimizing the time and cost of pipeline repairs. > PEX-a designs can be prefabricated, saving time and money on the front end. > With pipe support, PEX-a can be spaced similarly to copper, meaning no extra costs for hangers. > Fewer chemicals need to be added to a PEX-based hydronic system to prevent pit - ting, scaling and corroding. > The product's light weight lessens the need for heavy machinery, such as forklifts and cranes, to move it. > Making PEX connections involves no hot work. That eliminates the need — and the expense — for fire-watch measures. HVACPproducts.com HVAC & Plumbing Product News \ Summer 2018 16

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