The Plast-O-Matic CKM series check valve has a diaphragm design to prevent reverse flow of extremely corrosive liquids, and can be mounted in any position. The valve body is made of polypropylene for excellent chemical and corrosion resistance and rigidity. Viton(R) seat provides extreme temperature and chemical resistance. It has female NPT threads for connecting to male threaded pipes, creating a tighter seal than straight threads. The cracking pressure is 1.0 pounds per square inch (psi), and the maximum pressure rating is 100 psi. The maximum working temperature range is 77 to 140 degrees Fahrenheit.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.Plast-O-Matic Valves, Inc. manufactures plastic valves and controls for corrosive and ultra-pure liquids. The company, founded in 1967 and headquartered in Cedar Grove, NJ, meets certification standards.