System 636 PVC is classified as Type BH Class II A vent, suitable for use on appliances with flue gas temperatures up to and including 65 deg C (149 deg F). Sizes include 40, 50, 65, 75 and 100mm (1-1/2, 2, 2- 1/2, 3 and 4). Coloured white with unique blue certification markings, System 636 PVC pipe is made to sturdy Sch. 40 dimensions to provide a strong, rigid pipe for the application. A full range of certified vent fittings and accessories offered.