China butterfly valve design and selection

Author:China butterfly Valve Manufacturer     Published time:2018-04-30 08:30     Reading times:422    

1 China Butterfly Valves Overview


The butterfly valve is an important device in the water supply and drainage pipe system. With the progress of industrial technology, different requirements have been put forward for the structure and performance of the butterfly valve. Therefore, during the design and selection, reasonable choices should be made according to the working conditions and their types, materials and connection types.


2 China Butterfly Valve Design


China butterfly valve structure, butterfly valve closure (butterfly plate) in the middle of the media, the design should consider the impact of its convection resistance.


Regarding the structure of the large-diameter butterfly disc, AWWA C504 (American Water Supply Engineering Association Standard) stipulates that the disc should not have transverse ribs and its thickness should not be greater than 2.25 times the diameter of the stem.

The facing surface and outlet surface of the butterfly plate should be streamlined.

The internal screws cannot protrude outside the butterfly plate to avoid increasing the area of the water.

In order to reduce the flow resistance, a butterfly valve produced by a foreign company makes the butterfly plate discus-shaped, and the company also makes the butterfly valve of the small butterfly valve very thin, while the butterfly valve used in the hydropower pipe network has a deflector in the fully open position. All to reduce the flow resistance. China's JB/T 53171-1999 standard also sets the flow resistance and flow coefficient of the international standard ISO/TC 153/SC1GT8-37


3 Chinese butterfly valve selection

 

The butterfly valve has different structures such as single eccentricity, inclined plate type, center line type, double eccentricity and triple eccentricity. The medium pressure acts on the valve shaft and the bearing through the butterfly plate. Therefore, when the high-pressure small-diameter flow resistance is large, the shaft diameter and the thickness of the butterfly plate are correspondingly increased. If the gate valve and the ball valve or the cut-off valve are used, the sealing and flow resistance etc. Analysis is more appropriate than using butterfly valves.


In recent years, the appearance of the soft seal gate valve in the water system has improved the shortcomings of easy sedimentation of the gate valve. Its flow resistance is relatively small, and it can be maintained online. It is suitable for small and medium calibers and has been gradually applied.


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