What are the common check valves?
Classification:
Release Time：2021-05-21
Check valve refers to the opening and closing parts for the circular disc and by its own weight and medium pressure to produce action to block the medium back flow of a valve. It is an automatic valve, also known as check valve, one-way valve, return valve or isolation valve. Common check valves are the following.
Check valve refers to the opening and closing parts for the circular disc and by its own weight and medium pressure to produce action to block the medium back flow of a valve. It is an automatic valve, also known as check valve, one-way valve, return valve or isolation valve. Common check valves are the following.
1. lift check valve: Vertical and horizontal. The shape of the valve body of the lift check valve is the same as that of the cut-off valve, so its fluid resistance is large. The disc slides along the vertical centerline of the valve body. When the medium is flowing, the valve flap is opened by the medium thrust. When the medium stops flowing, the valve flap is dropped on the valve seat.
1. Vertical lifting check valve. The direction of the medium inlet and outlet channel is the same as the direction of the valve seat channel, and its flow resistance is smaller than that of the straight-through type. Vertical lift check valve installed in vertical pipeline.
2. The straight-through lifting check valve can only be installed in horizontal pipelines. Limited by the installation requirements, commonly used in small diameter occasions DN<50.
2. swing check valve: Swing check valve disc is disc-shaped, rotating movement around the rotating shaft of the seat channel, due to the flow of the valve channel into a linear, flow resistance than the lift check valve is small, suitable for small and medium caliber, low pressure large diameter pipe (low flow rate and flow changes are not often large diameter occasions). Sealing performance is not as good as lift type.
1, swing check valve is divided into single disc type, double disc type and most of the three types, these three forms are mainly divided according to the valve caliber, the purpose is to prevent the medium to stop flow or reverse flow, weaken the hydraulic impact. Single disc swing check valve is generally suitable for medium caliber occasions. Large diameter pipeline selection of single disc swing check valve, in order to reduce the water hammer pressure, it is best to use the slow closing check valve can reduce the water hammer pressure. Double disc swing check valve is suitable for large and medium diameter pipeline. Clamped double disc swing check valve structure is small, light weight, is a fast developing check valve; multi disc swing check valve is suitable for large diameter pipeline.
2, swing check valve installation position is not limited, it can be installed in the horizontal, vertical or inclined pipeline.
3. butterfly check valve: Straight-through. The structure of the butterfly check valve is similar to the butterfly valve. Its structure is simple, the flow resistance is small, and the water hammer pressure is also small. The valve flap rotates around a pin in the seat of the check valve. Disc check valve structure is simple, can only be installed in the horizontal pipe, poor sealing.
4. diaphragm check valve: There are many structural forms, all of which use diaphragms as opening and closing parts. Due to its good waterproof hammer performance, simple structure and low cost, it has developed rapidly in recent years. However, the use of diaphragm check valve temperature and pressure by the diaphragm material restrictions.
Diaphragm check valve is suitable for pipelines prone to water hammer. Diaphragm can well eliminate water hammer generated when medium flows back. It is generally used on low pressure and normal temperature pipelines, especially on tap water pipelines. Generally, the working temperature of medium is between -12-120 ℃ and the working pressure is <1.6MPa. However, diaphragm check valve can achieve larger diameter, DN can reach more than 2000mm at most;
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