Check valves are mechanical devices designed to allow fluid—whether liquid, gas, or steam—to flow in one direction while preventing reverse flow. They operate automatically, opening when the upstream pressure exceeds the downstream pressure and closing when flow reverses. This function helps protect pumps, compressors, and pipelines from potential damage caused by backflow, and it also maintains system efficiency. Common types of check valves include swing, lift, ball, and dual-plate designs, each selected based on the application’s flow rate, pressure, and media characteristics. They are widely used in industries such as oil and gas, power generation, water treatment, and chemical processing.