The following outlines Radiant Floor Company’s 7/8″ Durapoly XL tubing specifications:
PEX: Polyethylene is a highly useful and common material that is most set in pellet form. These pellets are often utilized in the making of milk and water cartons (and many other food item containers etc.).
Pex is a standard “Industry” product, with a multitude of uses. “PEX” is an Acronym for “Poly-Ethylene”, that is “Cross-linked”- (X) = ….”P E X”!
“Pex” tubing begins as Polyethylene, a derivative of Natural Gas. It is then processed into the form of pellets, these pellets are later melted down and run through an “Extruder”, This is known as the “Extrusion process”, the process by which polyethylene tubing is created.
“Cross-linking” alters the molecular structure of the polyethylene tubing. Once completed, this change strengthens the polyethylene tubing (now Pex), enabling greater pressures and higher temperatures.
There are three cross-linking processes. The first two (most common) types of cross-linking are “Peroxide” (type-“A”) and “Silane” (type “B”), these are chemical cross-linked Pex. The third process is known as “Electron beam” (Type “C”) Electron beam Pex.
Radiant Floor Company’s Pex tubing (type “B”) is suitable for domestic applications.
Dura-Poly XL Radiant Floor Company Heat Exchanger Cross-linked Polyethylene (PEX) Tubing and Dura-Poly XL Radiant Floor Company Oxygen Barrier Heat Exchanger Cross-linked Polyethylene.
CB Supplies Ltd. manufacturers Dura-Poly XL Radiant Floor Company Heat Exchanger Cross-linked Polyethylene (PEX) Tubing and Dura-Poly XL Radiant Floor Company Oxygen Barrier Heat Exchanger Cross-linked Polyethylene (PEX) Tubing for the Radiant Floor Company. The PEX tubing is manufactured in two sizes for the Radiant Floor Company, 1/2″ nominal size CTS SDR9 and 7/8” nominal size SIDR 11.5.
BACKGROUND:
PEX-b tubing is manufactured by blending Polyethylene resin that has saline grafts with a resin containing a catalyst. The mixture then goes through the extrusion process where the mixture is melted and the tubing formed, cooled, and coiled. The coiled tubing then must go through a steam sauna for the cross-linking between the saline grafts to occur.
MATERIALS:
The material properties of the base resin are as follows:
MATERIAL PROPERTIES:
Property Test Method English Units SI Units
Density ASTM D1505 – 0.944 g/cc
Melt Index1 (190°C/2.16 kg) ASTM D1238 – 0.1 g/10 min
Flexural Modulus2 ASTM D790 152,000psi 1050MPa
Tensile Strength @ Yield (2 in/min) ASTM D638 >3,500 psi >24.1MPa
Coefficient of Linear Thermal Expansion (20°C – 70°C) DIN 53752A 8×102/°F 1.5 x10-5/°C
Hydrostatic Design Basis @73°F (23°C) ASTM D2837 1250 psi 8.6MPa
Hydrostatic Design Basis @180°F (82°C) ASTM D2837 800 psi 5.5MPa
Vicat Softening Point ASTM D696 255° F 124° C
Thermal Conductivity ASTM D 177 2.4 Btu-in/(hr)(ft2)(°F) 3.5×10-3 Watts/(cm2)(°C/cm)
When Dura-Poly XL Radiant Floor Company Heat Exchanger Cross-linked Polyethylene (PEX) Tubing CTS SDR9 and Dura-Poly XL Radiant Floor Company Oxygen Barrier Heat Exchanger Cross-linked Polyethylene (PEX) Tubing are marked with ASTM F876/F877 and CSA B137.5 it affirms the products was manufactured, inspected, and tested in accordance with these specifications and meet the specified requirements.
The specifications for manufacturing the SIDR11.5 Dura-Poly XL Radiant Floor Company Heat Exchanger Cross-linked Polyethylene (PEX) Tubing CTS SDR9 and SIDR11.5 Dura-Poly XL Radiant Floor Company Oxygen Barrier Heat Exchanger Cross-linked Polyethylene (PEX) Tubing were provided by the Radiant Floor Company and the same manufacturing, inspection, and testing as the CTS SDR9 PEX tubing are followed to ensure the SIDR11.5 PEX tubing meets the specifications provided.
Oxygen Barrier Pex is “Pex” with an outer coating, designed to eliminate / minimize oxygen permeation, aka “Oxygen diffusion”, Although studies indicate that if water temperatures remain below 140 degrees, no significant amount of “oxygen diffusion” will occur…. For Closed Radiant heating systems, certain boiler manufacturers simply require oxygen barrier Pex tubing (in Closed radiant heating systems) for warranty purposes. This despite the fact that none of the experts seem to agree on how much, if any, damage is being done to the radiant system. As mentioned above, at normal, low radiant temperatures, oxygen diffusion is minimal. Is it worth spending more on tubing in order to, maybe, prolong the life of the system? Especially since non-barrier tubing has been used for years in low temperature systems without any reports of accelerated damage. Although we do offer Barrier pex, we’ve seen no ill effects in any of our Radiant heating systems,..Open or Closed,…with or without Barrier pex.