Wafer Check Valve

Wafer type check valves have Short face-to-face dimensions and low weight, and provide an economical, space-saving solution when compared to traditional swing check valves. 

Dual-plate wafer check valve

Dual-plate check valves are are bonnetless and mounted between pipe flanges (wafer style). In this case, the valve includes two spring loaded half-moon shaped discs that rotate about their shaft. The actual designs of these valves vary between design models and manufacturers. Most have multiple flat seats. The dual-plate check valve disc has short rotational disc travel and responds quickly to flow stoppage or reversal, thus the potential for moderate water hammer does exist. It is somewhat better than the swing check valve at minimizing potential water hammer, but with a much higher pressure drop.

Depending on the design, maintenance effort ranges from relatively simple to difficult. All dual-plate check valves must be removed from the line to perform maintenance due to the bonnetless design. The dual-plate check valve also results in a higher pressure drop when compared to a tilting disc check valve of the same size.

Single-plate wafer check valve

Single-plate wafer check valves(lift type) 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. 

And another thin type single-plate wafer check valves are swing type, that performs the same with swing check valve with much less cost. The disadvantage of this single-plate wafer check valves is, the inside diameters of the valves can only meet 60-80% of Norminal Pipe Size(NPS),  which limits the flow coefficient.