PEX-A tubing is cross-linked, high-density polyethylene. All Apollo® Expansion PEX is opaque in color and ensures easy identification of hot, cold and main water lines through different colored print lines. Apollo® Expansion PEX pipe is produced using the high-pressure peroxide method for crosslinked polyethylene (PEXa) in accordance with ASTM F876, F877, CSA B137.5 and PPI TR-3 and is certified to NSF 14/61 standards. Apollo® Expansion PEX pipe also meets the requirements of ASTM F2023 for chlorine resistance. Apollo® Expansion PEX pipe is manufactured using a quality management system which has been certified to the latest version of ISO 9001. Use of Apollo® Expansion PEX pipe in heating systems requires corrosion protection and/or isolation by using a heat exchanger or non-ferrous components throughout the system.