Foot valve

A foot valve is a sort of check valve that is often located at the bottom of a pipeline or at a pump (hence the name). Foot valves function similarly to ball check valves, but they have an open end with a shield or screen covering it to prevent debris from entering the line.
Foot valves keep the suction line between the tank and the pump set primed by preventing oil from returning to the main tank. Foot valves offer a better level of safety than check valves, which may be situated closer to the pump set.