TYPES OF VALVES
Straight body swing check valves contain a disk that is hinged at the top. The disk seals against
the seat, which is integral with the body. This type of check valve usually has replaceable seat
rings. The seating surface is placed at a slight angle to permit easier opening at lower pressures,
more positive sealing, and less shock when closing under higher pressures.
Swing check valves are usually installed in conjunction with gate valves because they provide
relatively free flow. They are recommended for lines having low velocity flow and should not
be used on lines with pulsating flow when the continual flapping or pounding would be
destructive to the seating elements. This condition can be partially corrected by using an
external lever and weight.
Tilting Disk Check Valves
The tilting disk check valve, illustrated in Figure 23, is similar to the swing check valve. Like
the swing check, the tilting disk type keeps fluid resistance and turbulence low because of its
Tilting disk check valves can be installed in horizontal lines and vertical lines having upward
Figure 23 Operation of Tilting Disk Check Valve
flow. Some designs simply fit between two flange faces and provide a compact, lightweight
installation, particularly in larger diameter valves.