Applicable media of U-type butterfly valve: fresh water, sea water, air, steam, food, medicine, and various oils, acids, alkalis, salts, etc. Features: long service life, reliable sealing performance and no regular maintenance. The flow characteristic of butterfly valve is 3 times that of stop valve and 75% of that of gate valve of the same specification. Butterfly valve can realize the switching and regulating functions of fluid in the pipeline. Compared with gate valve and stop valve, it has better multifunctional type. With a variety of choices of Internals and elastic materials, butterfly valves are widely used in the chemical field.