The Asahi America True Union check valve employs a free moving ball, which unseats to permit flow in one direction, but seals against a seat to prevent back flow. It can be installed vertically or horizontally. The valve body is made of polyvinyl chloride (PVC) for corrosion resistance, high strength, and less weight than fittings made from metal. PVC can be connected to other materials such as steel, copper, or cast iron using transition fittings, and it is suitable for cold water, venting, and waste applications. This valve has an ethylene propylene diene monomer (EPDM) seat, which provides increased resistance to water and chemicals, and has a solid thermoplastic ball. It has a socket-weld end for connecting to unthreaded pipe ends and National Pipe Taper (NPT) threads for creating tighter seals than straight threads. Minimum shut-off is 5 pounds per square inch (psi), and the working temperature range is 30 to 120 degrees Fahrenheit. This valve meets National Sanitation Foundation (NSF) 61 for quality assurance.
Check valves have two ports and restrict the flow of fluids and other loose materials through a pipe or passageway to one direction. Flow enters through one port and exits through the other, closing when flow reverses or stops. Two common types of check valves are ball cone valves and swing check valves. A ball cone valve utilizes a spring-loaded ball seated against a cone-shaped interior surface to stop the flow of fluid in a forward direction, and a swing check valve has a movable disc on a hinge to block reverse flow. Check valves are rated by their cracking pressure (the minimum upstream pressure required for the valve to operate), and they are used in various water, gas, air, and steam lines.
Asahi/America manufactures corrosion-resistant fluid products. The company, founded in 1971 and headquartered in Malden, MA, meets International Organization for Standardization (ISO) 9001:2008 and 14001:2004, ATEX, RoHS, and NSF-61 certification standards.