Gate valve
(12)
Ball valve
(15)
Check valve
(9)
Globe valve
(7)
Butterfly valve
(6)
Knife gate valve
(5)
Forged steel valve
(12)
Cryogenic valve
(3)
Single-plate wafer check valve
Single-plate wafer check valves prevent reverse flow with disc movement that is parallel with the flow. With this design, the disc is always in the flow path. Discs are spring-loaded to assist in seating. These wafer type check valves are bonnetless and are installed between flanges. The type of check valve disc has very short disc travel and responds very quickly to flow stoppage or reversal, thus minimizing the potential for water hammer. It is somewhat better than the tilting disc check valve at minimizing potential water hammer, but with a higher pressure drop.
Depending on the design, all wafer check valves must be removed from the line to perform maintenance due to the bonnetless design. The in-line disc design produces the most pressure drop when compared to other check valves of the same size.