Principles, structural features and applied scope
1 Principles, structural features
Butterfly valve has a simple structure, small size, light weight, little material consumption, small installing size, fast switching, 90°back and forth rotation, small driving torque characteristics, used for cutting off, connecting, regulating the pipeline medium, with good fluid control features and closed sealing performance. When butterfly valve is in the fully open position, the disc thickness is the only resistance that the medium flows through the body, so the pressure drop through the valve is very small, so it has good flow control characteristics. butterfly valve sealing types are flexible sealing and metal sealing types. Elastic sealing valves, sealing ring can be mounted on the body or attached to the around disc.
Stem is through rod structure, after quenching and tempering treatment, there is a good comprehensive mechanical properties and corrosion resistance, scratch resistance. When butterfly valve opens and closes, the stem only do rotation but not for lifting operation, and the stem packing is not easily damaged, sealing is reliable. Fixed With the butterfly plate-cone pin, the overhang end is designed to prevent rush out, in order to avoid stem breaking out when the stem and disc junction cracks unexpectedly.
2 applied scope
Using metal sealed valves life is generally longer than elastic sealing valve, but it is difficult to achieve completely sealed. Metal seal can adapt to a higher operating temperature, flexible sealing has the defect that is restricted by temperature.
If you require the butterfly valve used as flow control valve, mainly choice is the right size and type of valve. Butterfly valve structural principle is particularly suitable for production of large-diameter valves. Butterfly valve is widely used not only in oil, gas, chemicals, water treatment, etc. general industry, but also applied to thermal power plant cooling water systems.
Industry-specific butterfly valves characteristics are high temperature resistance, suitable pressure range is quite high, the valve nominal diameter is large, body uses carbon steel, disc sealing ring uses metal ring to replace rubber sealing ring. Large-scale high-temperature butterfly valve uses steel plate welding, mainly used for high-temperature medium duct smoke and gas pipelines
