ZurnPEX® QickSert CR™ coupling. The QQPC_X coupling is used to connect PEX tubing to PEX tubing. Molded from Acudel®. These fittings, as a system with Zurn PEX® tube, are pressure rated at 160 PSI at 73 deg F, 100 PSI at 180 deg F, and 80 PSI at 200 deg F. These fittings are listed by NSF as complying with the following standards NSF/ANSI Standard 14, NSF/ANSI Standard 61, ASTM F877, and CSA B137.5, and ASTM F2159.