Check valves are basically the type of valves which prevent the backflow of the fluid or gas traveling through that specific pipeline. The liquids or gases flowing through non-return valves flow in single direction mainly. These poppet check valves consist of two openings which mainly allows the fluid or gas to enter from one end and leave from the other end. If the flow turns and no check valve is installed, water hammer can occur. Water hammer often occurs with an extreme force and will easily damage a pipeline or components. Check valves are used in many different applications. For example they are often placed on the outlet side of a pump, to protect the pump from backflow. Centrifugal pumps are not self-priming, and therefore check valves are essential for keeping water in the pipes. Also, check valves are very often used in HVAC-systems (Heating, Ventilating and Air Conditioning-systems).
