In recent years, with the development of modern industry, the use of butterfly valves has expanded from low-pressure water supply to medium temperature higher than 538 ° C, low to -184 ° C, pressure from low to high, widely used in air separation, chemical, metallurgy , sewage treatment and other fields. Moreover, the caliber is getting larger and larger, the performance requirements are higher, and the service life is longer. At present, most of the butterfly valves produced at home and abroad are rubber seals and plastic seals, which are prone to wear and aging, and fail to meet the continuous operation cycle of the equipment. Taking air separation as an example, today's air separation plant based on the principle of cryogenic separation uses the molecular sieve pre-purification process, the working pressure is 0.5-0.9mpa, the medium temperature varies from 10 to 200 °C, and the switching valve is used. The temperature difference is large, the caliber is large, the switching is frequent, the valve rubber sealing ring is easy to wear and aging, and the replacement is also difficult.
Structure and working principle
Lever type opening and closing structure
Lever type opening and closing structure. When the butterfly valve is closed, the main shaft and the lever are fastened with the taper pin, and the o-point rotates counterclockwise. The lever uses the holed pin to drive the disc ab, and the compression spring pushes the disc to be fixed on the fulcrum n of the lever, with the spindle lever Turn and turn. When the upper end b of the butterfly plate is in contact with the sealing surface of the valve body, the sealing is achieved. The opening process is just the opposite. During the opening and closing process, the relative sliding between the sealing pairs is small, reducing relative wear. In the closed state, the axial pressure seal changes the conventional external force squeeze seal.
Metal flat seal pneumatic butterfly valve features
(1) The lever type opening and closing structure is adopted to make the relative sliding between the sealing pairs small and reduce the relative wear.
(2) It adopts metal flat sealing structure, has strong corrosion resistance and wear resistance, is suitable for high temperature environment and has long service life.
(3) The actuator adopts a connecting rod force increasing mechanism. When the butterfly valve is in the closed state, the driving device can output the maximum torque, and has self-locking performance, and the work is safe and reliable.
(4) The control system of the valve adopts non-contact electromagnetic reed switch, which is not restricted by environmental conditions, and has sensitive signal and high accuracy. It can realize remote control, pneumatic control and automatic control. People operate.
(5) The key components have been optimized so that the total number of valve opening and closing can reach 1×106 times.