A valve, especially one in a water pipe, which allows fluid to flow in one direction only and which automatically closes when flow ceases or reverses. These valves are very useful in preventing back flow of water to the pump. These valves have minimum head loss and can be very competitive in terms of long service life. These valves are very useful in waterworks pipelines to reduce hammer effect. Non slam and quick closing characteristics have made this product a very demandable one across markets.