Swing check valve, a typical one of check valves (non-return valves), normally allows fluid (liquid or gas) to flow through it in only one direction, which should be horizontally installed and work automatically and not controlled by a person or any external control; accordingly, most do not have any valve handle or stem.Swing Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave.

Swing Check Valves are designed in accordance to BS 1868, or API 6D.