Telescopic butterfly as a piping system used to implement off and flow control components, has been very widely used in many fields of petroleum, chemical, metallurgy, water, electricity. Telescopic butterfly butterfly plate installed on the pipe diameter direction. Cylindrical channel in the valve body, disc-shaped disc around the axis of rotation, rotation angle between 0 ° ~ 90 °, rotated to 90 °, the valves are open all license conditions. This valve is usually installed horizontally. Telescopic butterfly has a simple structure, small size, light weight, material consumption province, small installation size, switch quickly, 90 ° reciprocating rotary drive torque characteristics of small, used to cut, turn, adjust the line of medium, with good fluid sealing properties and closing control characteristics. Retractable Butterfly in the fully open position, retractable butterfly thickness is only when the medium flows through the body resistance, produced by the valve pressure drop is small, it has a better flow control characteristics. Telescopic a bomb and metal sealing butterfly valve seal sealing two kinds of patterns. Elastic sealing valves, seals can be mounted on the body or attached to the disc periphery. Telescopic butterfly valve with long life metal sealing valves generally than the elastic seal, but it is difficult to completely seal. Metal seal can adapt to higher operating temperature, flexible seal is restricted by temperature defects. If you require the use of telescopic flow control valve as the main choice is the right size and type of valve. Telescopic butterfly structure principle is particularly suitable for production of large diameter valves. Retractable Butterfly not only widely used in the oil, gas, chemical, water treatment and other general industries, but also for the thermal power plant cooling water system. Commonly used telescopic butterfly valve wafer butterfly valve, butterfly valve flanged, welded butterfly three. Wafer type butterfly valve with stud connection between two pipe flanges; flanged butterfly valve is a valve with a flange with bolts on the valve flange connection on both ends of the pipe flanges; Butt both ends of the butterfly valve and pipe welding surface connection. Disc streamlined design, the fluid resistance loss, can be described as an energy-saving products. To pass the stem rod structure, after quenching, with good mechanical properties and corrosion resistance, scratch resistance. When the valve opening and closing the valve stem and not only for rotary motion for the lifting operation, the valve stem packing is not easy to destroy, reliable sealing. And disc taper pin fixed, extended end to prevent out design, in order to avoid the stem and disc connected to the stem of the accident when the collapse of the fracture. 1, small, lightweight, easy installation and maintenance, and can be mounted in any position. 2, the structure is simple, compact, low operating torque, 90 degree rotation to open quickly. 3, the flow characteristics of linear trend, regulated performance. 4, the disc-free connection with the stem pin structure, it is possible to overcome the internal leaks. 5, the seals can be replaced, and reliable sealing achieve bi-directional sealing. 6, the disc can be sprayed coatings based on user requirements, such as nylon or PTFE classes. 7, the valve can be designed into flanged and wafer. 8, drive optional manual, electric or pneumatic.