Basic Check Valve Design

The Swing Check...companion for gate valves

Swing checks work automatically as shown here.  But whether used in a horizontal line or vertical line for upward flow, they will not function properly unless installed with pressure under the disc.

Flow through swing checks is in a straight line and without restriction at the seat, similar to a gate valve.  This similarity in effect on flow is the reason for generally using swing checks in lines in combination with gate valves.

The Lift Check...companion for globe valves

Lift checks also operate automatically by line pressure.  They should be installed with pressure under the disc.

Like the globe valve with its indirect line of flow, the lift check is restricting to flow.  For this reason it is generally used as a companion to globe valves.