Butterfly valve development history

The butterfly valve was invented in the United States in the 1830s. At present in the world generally in DN300mm above butterfly valve has gradually replaced the gate valve. Compared with gate valve, butterfly valve has short opening and closing time, small operating torque, small installation space and light weight. Take DN1000 as an example, the butterfly valve is about 2T, and the gate valve is about 3.5T, and the butterfly valve is easy to combine with various driving devices, has good durability and reliability.

Industrial special butterfly valve features high temperature resistance, applicable pressure range is also high, the valve nominal diameter is large, the valve body is made of carbon steel, the sealing ring of the valve plate uses metal ring instead of rubber ring. Large high temperature butterfly valve made of steel plate welding, mainly used for high temperature medium smoke duct and gas pipeline.

The disadvantage of the rubber sealed butterfly valve is that when it is used for throttling, cavitation will occur due to improper use, so that the rubber seat spalling and damage occur. Therefore, now the international development of metal seal butterfly valve, cavitation zone is reduced.

General sealing seat life under normal conditions, rubber 15-20 years, metal 80-90 years. But how to choose correctly depends on the requirements of working conditions:

1, the relationship between the opening of the butterfly valve and the flow rate, basically linear proportional change. If it is used to control the flow, its flow characteristics are also closely related to the flow resistance of the pipe. For example, the diameter and form of the valve installed in two pipelines are all the same, and the pipeline loss coefficient is different, and the flow of the valve will be very different.

2. If the valve is in a large throttle range state, the back of the valve plate is prone to cavitation, and there is the possibility of damage to the valve, which is generally used at 15°.

3. When the butterfly valve is in the middle opening, the valve body and the front end of the butterfly plate form the opening shape with the valve shaft as the center, the two sides form different states, one side of the front end of the butterfly plate moves in the direction of the flow water, the other side moves in the direction of the countercurrent water, therefore, one side of the valve body and the valve plate form a nozzle shaped opening, the other side is similar to the orifice orifice opening, the nozzle side is much faster than the throttle side flow rate, And the throttle side valve will produce negative pressure, often appear rubber seals fall off.

4, butterfly valve operating torque, because of the opening degree and valve opening and closing direction of different values, horizontal butterfly valve, especially large diameter valve, due to the water depth, valve shaft, water head torque generated by the difference can not be ignored. In addition, the valve inlet side device elbow, the formation of bias, torque will be increased. When the valve is in the middle opening, the operating mechanism needs to be self-locking due to the action of water flow torque.

At present, butterfly valve as a component used to realize pipeline system on and off and flow control, has been widely used in petroleum, chemical industry, metallurgy, hydropower and many other fields. In the well-known butterfly valve technology, the sealing form of the sealing structure, sealing material for rubber, PTFE and so on. Due to the limitation of structural characteristics, it is not suitable for high temperature, high pressure, corrosion resistance, wear resistance and other industries.