Check valves generally used to prevent flow reversal in piping systems and connected equipment.
Two types of check valve is there working principle as below.
- Swing check
- Lift check
Swing check valve
The swing check valve design consists of a hinged disk that swings open when flow starts in the desired direction and swings closed in flow reversal situations. Because of this swinging action of the disk, it is important to install all swing check valves so that the disk closes positively by gravity. When fully open, the swing check offers less flow resistance than the lift check valve design.In flow situations where shock closure and/or disk chatter are encountered.
Swing check valves with outside lever and weight arrangements or spring-loaded disks can facilitate immediate closure in flow reverse. This immediate closure minimizes the possible damages of shock and disk chatter in systems. The tilting-disk swing check valve is another type of swing check valve that is used to help prevent slamming
Lift check Valve
The lift check valve design is used in situations where pressure drop is not considered critical. The flow pattern through the valve corresponds to that of the globe valve. Lift check valves are available in horizontal and vertical designs.
A lift-check valve is a check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly.