1. Swing check valve: swing check valve disc disc, around the seat channel shaft for rotating movement, because the channel in the valve into streamlined, flow resistance than the lift type check valve is small, suitable for low velocity and flow does not change the large caliber occasion, but is not suitable for pulsating flow, its sealing performance is not as good as the lift type. Swing check valve is divided into single-disc type, double-disc type and mostly type three, these three forms are mainly divided by the valve diameter, the purpose is to prevent the medium to stop flowing or flow back, weaken the hydraulic impact.
2. Lifting check valve: the valve disc along the vertical centerline of the valve body sliding check valve, lifting check valve can only be installed on the horizontal pipeline, in the high pressure small diameter check valve can be used on the disc ball. Lift type check valve body shape and globe valve (and globe valve general), so its fluid resistance coefficient is larger. The structure is similar to the globe valve, and the body and disc are the same as the globe valve. The upper part of the valve disc and the lower part of the valve cover is processed with a guide sleeve, the valve disc guide can be freely lifted in the valve guide, when the medium flow, the valve disc by the medium thrust open, when the medium stops the flow, the valve disc by the vertical landing on the valve seat, to prevent the medium countercurrent effect. Straight lift check valve medium inlet and outlet channel direction and seat channel direction perpendicular; Vertical lift check valve, the medium inlet and outlet channel direction and seat channel direction is the same, the flow resistance is smaller than the straight-through type.
3. Disc check valve: the valve disc around the pin in the seat rotation of the check valve. Disc type check valve structure is simple, can only be installed in the horizontal pipeline, poor sealing.
4. Pipe check valve: valve with disc sliding along the center line of the valve body. Pipe check valve is a new valve, its small size, light weight, good processing technology, is one of the development direction of check valve. But the fluid drag coefficient is slightly larger than swing check valves.
5. Compression check valve: this valve is used as boiler feed water and steam cut off valve, it has the comprehensive function of lifting check valve and globe valve or Angle valve.
In addition, some are not suitable for pump outlet installed check valves, such as bottom valve, spring type, Y type, etc.