The Milwaukee Valve UP509 series bronze swing check valve with female National Pipe Taper (NPT) threads on both ends is suitable for potable water service and is used for restricting fluid flow to one direction. It has a hinged disc that swings onto the seat of the valve to block reverse flow. The valve body is made of American Society of Testing and Materials (ASTM) B-584 bronze for strength and corrosion resistance. This valve has maximum pressure ratings of 300 pounds per square inch (gauge) (psig) for water, oil, and gas (WOG) and a cracking pressure of 0.5 psi. It has female NPT threads on both ends for connecting to male threaded pipes with tighter seals than straight threads. This valve is for use in water lines, processing plants, and agricultural applications and meets standard Manufacturers Standardization Society (MSS) SP-80 for quality assurance. The UP509 was designed in accordance with the requirements of California Assembly Bill 1953, Vermont Senate Bill S.152, and U.S. Senate Bill S3874 which limit the amount of lead in plumbing fixtures that come in contact with water intended for human consumption.

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.

The Milwaukee Valve Company manufactures manual and actuated valves, controls, and control accessories. The company, founded in 1901, and headquartered in New Berlin, WI, meets International Organization for Standardization (ISO) 9001:2008 and 14001:2004 standards.