Pneumatic valve

The fork type pneumatic cut-off butterfly valve can quickly cut off the flow of medium in the pipeline, using a single acting cylinder and a spring type pneumatic actuator. Widely used in gas waste heat power generation systems and extraction heating steam turbine systems as a system safety guarantee. Close quickly with low flow resistance.拨叉式气动切断法兰蝶阀是针对工业流程快速截断需求开发的高效控制装置，采用机械拨叉传动与法兰连接结构，在石油化工、燃气输配、冶金能源等需要快速响应的介质截断场景中具有重要应用价值。该设备通过优化的力臂传动比与密封系统设计，实现0.5-2秒内完成90°启闭动作，需要满足SIL2安全完整性等级的紧急切断要求。

‌结构设计与运行特性‌
The valve body adopts a flange connection structure, which complies with the GB/T 9113/HG/T 20592 standard and is compatible with DN50-DN1200 pipeline specifications. The fork type pneumatic actuator converts the linear motion of the cylinder into the rotational motion of the valve stem through a precision machined crank slider mechanism. The transmission efficiency is 40% higher than that of traditional gear rack type, and the maximum output torque can reach 12000N · m. The double eccentric valve plate structure enables the sealing surface to quickly detach from the valve seat when opened, forming a gradual wedge-shaped compression when closed, effectively reducing over 85% of the opening and closing friction loss. The valve seat is made of stainless steel matrix and reinforced graphite composite layer, with a temperature resistance range of -29 ℃~425 ℃ and a pressure rating covering PN16-PN40.

‌材料与制造工艺‌
The valve body material can be WCB carbon steel, CF8M stainless steel or nickel based alloy, and the surface is treated with epoxy resin spraying or sandblasting passivation. The corrosion resistance meets the NACE MR0175 standard. After precision CNC machining, the valve plate is subjected to surface hardening treatment (hardness ≥ HRC45), and the contact surface with the valve seat is polished with a mirror finish (Ra ≤ 0.4 μ m). The fork transmission component is forged from 42CrMo alloy steel and undergoes nitriding treatment to achieve a surface hardness of HV800 and a tensile strength of ≥ 1000MPa. The sealing system needs to pass the API 598 standard test, with a leakage rate of ≤ 5 × 10 ^ -6 mL/s · m under bidirectional pressure of 6MPa, and meet the Class VI sealing requirements.

‌气动控制系统配置‌
The actuator is equipped with a modular cylinder unit, and the cylinder body is made of aluminum alloy precision casting. The surface of the piston rod is plated with hard chromium. Support gas source pressure of 0.4-0.7MPa, full stroke action time ≤ 1 second, repeat positioning accuracy ± 0.5 °. Explosion proof configuration requires ATEX/IECEx Ex d IIB T4 certification, with a protection level of IP67, and can operate stably in Class II explosive gas environments. The control system can be equipped with an intelligent valve positioner, which supports 4-20mA/HART communication protocol and has valve opening feedback and fault diagnosis functions. Standard manual unlocking device, which can be used for emergency operation through the worm gear mechanism in case of gas loss.

‌应用与适配场景‌
This valve achieves an emergency cut-off response of ≤ 0.8 seconds in natural gas pressure regulating stations, and is suitable for working conditions with particulate media (solid content ≤ 15%), high-temperature steam (maximum instantaneous temperature 450 ℃), and highly corrosive chemical fluids. During installation, it is necessary to ensure that the flatness deviation of the pipeline flange is ≤ 0.2mm/m. It is recommended to install a 40 μ m precision filter pressure reducing valve in the gas source pipeline. It is recommended to check the wear of the valve seat sealing surface every 10000 actions during the maintenance cycle. When the thickness of the graphite layer is less than 1.5mm, the sealing component needs to be replaced. In the liquefied natural gas storage and transportation system, it is necessary to meet industry standards such as ASME B16.34/API 609.