Cleveland — After extensive testing and development by The Lubrizol Corporation, FlowGuard Gold® Pipe and Fittings and Corzan® Pipe and Fittings are listed by the International Code Council-Evaluation Service (ICC-ES PMG-1264) for use in return air plenums. The listing confirms that water filled (water distribution) and empty (condensate) ½” through 2” FlowGuard Gold Pipe and Read more