A check valve (also called a non-return valve) is a self-acting valve that permits flow in one direction only and closes automatically when flow reverses or pressure drops — with no manual intervention required. It protects pumps, compressors, and pipelines from damaging backflow, water hammer, and contamination. Typical applications include water supply, chemical processing, HVAC, and industrial plant. Fergo stocks all common types ready to ship — browse the full check valve range.