A check valve, also known as a non-return valve or one-way valve, is a valve that allows fluid to flow through it in only one direction. It is designed to prevent backflow, which is the reverse flow of fluids in a pipeline, and ensure the unidirectional fluid flow in the piping system. Check valves are cheap, effective, and easy solutions to a potential issue. Backflow can cause a problem if the flow is contaminated and, therefore, contaminates the media upstream. Check valves are used in a wide range of applications, including water treatment plants, chemical processing, oil and gas production, food and beverage processing, and HVAC systems.
There are different types of check valves, including lift check valves, spring check valves, and swing check valves. A lift check valve consists of a guided disc that raises (lifts) off the valve seat to allow media flow. It requires a cracking pressure to open. A spring check valve is a valve that ensures unidirectional flow and prevents reverse flow. They have a single inlet and outlet and must be placed in proper orientation to function correctly. A swing check valve is a valve that swings open and closed on a hinge or pivot to allow or prevent flow.
Check valves can also have additional features, such as override control to stop flow regardless of flow direction or pressure, as in the case of a stop-check valve. A flow check is a check valve used in hydronic heating and cooling systems to prevent unwanted passive gravity flow.
In summary, a check valve is a unidirectional valve that passes fluid in one direction but prevents any flow in the opposite direction. It is designed to prevent backflow and ensure the unidirectional fluid flow in the piping system. Check valves are used in a wide range of applications and come in different types and with additional features.
