Check the listing for details. Brass Backflow Preventer 1/2" Atmospheric Vent Type Water 190T012. Condition: New – Open box. Listed at 55.00 USD. The Brass Backflow Preventer 1/2" Atmospheric Vent Type Water 190T012 is a plumbing device designed to prevent backflow of water in a 1/2 inch pipe. It features a brass construction, making it durable and resistant to corrosion. This atmospheric vent type backflow preventer is suitable for use with water as the suitable media, ensuring efficient and safe water flow in various industrial and commercial applications. Its compact size and reliable performance make it an essential component for maintaining the integrity of water systems.