The 4" Socket Black PVC True Union Industrial Ball Check Valve with EPDM O-Rings is designed for reliable performance in industrial and chemical processing applications. Its flow-tested design ensures quick response and a positive seal to prevent system backflow. Constructed from chemical and corrosion-resistant PVC, this valve is suitable for both horizontal and vertical installations. With strong, buttress thread union nuts and EPDM O-rings, it is pressure-rated to 150 PSI at 73°F and is NSF certified for potable water use. Additionally, it is suitable for vacuum service and assembled with silicone-free, water-soluble lubricants.