Swing check valves have plate disc rotating with spindle inside channel of seat. For channel having streamline shape, flow resistance of swing check valves is lower than lift check valves. Swing check valves are suitable for pipe having low flow speed and less variation. They are not suitable for pulsating flow. Sealing is poorer than lift check valves. Swing check valves are classified into single disc, double disc and multi discs. Three types of check valves are distinguished based on diameter of valve. They aim at reducing water hammer when medium stops flowing or back flows.
The disc of lift check valves slides with vertical center line of body. Lift check valves can be only installed at horizontal pipes. When the valves are used for high pressure small diameter pipe, the disc of valves adopts ball shape. The body shape of lift check valves is the same as globe valves (sometimes they can be in common use with globe valves). For that, lift check valves have high fluid resistance coefficient and the structure is the similar to globe valves. Body and disc are the same as globe valves. The top of disc and the bottom of bonnet is equipped with guide sleeve. Guide sleeve of disc can lift freely inside the guide sleeve of bonnet. When medium flow directly, disc is opened by thrust of medium. When medium stop flowing, disc land on seat in free-fall to prevent medium from back flowing.
Disc rotates with pin roll inside seat. Butterfly check valves have simple structure and they can be only installed at horizontal pipes.