"Liquid ammonia emergency shut-off valve" is a practical and safe valve invented by Zhang Gong, a senior engineer of Shanghai Five-Yuan Valves Technology Development Department. The invention is based on the assembly, adjustment and protection of gas storage tanks and ammonia storage tanks. Provide quality assurance. The liquid ammonia emergency shut-off valve uses a gas source (compressed air, nitrogen) and a solenoid valve to control the opening-closing of the valve, and is widely used in the inlet and outlet of a tank for gas, ammonia or weak corrosive gas. The liquid ammonia emergency shut-off valve is used in conjunction with a remote gas source, and the gas source is used to control the closing of the valve, so that when an accident occurs in the pipeline or the storage tank, the worker quickly touches the switch through the control room, and the electromagnetic valve is energized instantaneously, and the gas source is fast. By closing the valve. Pneumatic emergency shut-off valve internal structure placement {fusible alloy} melts when the outside temperature rises to ≥80 °C, blocks the air pipe, and the valve is relieved of pressure to protect it. The liquid ammonia emergency shut-off valve cylinder opening pressure ≥0.3-0.6Mpa, the daily working pressure of the cylinder, not less than 0.4MPa, to ensure the normal operation of the valve. The valve should be closed every day when it is not in production to avoid long-term compression fatigue failure of the spring and reduce the performance of the shut-off valve seal. Affects normal work production. The medium flowing through the valve body should be a gas free of impurities and particles. The liquid ammonia emergency shut-off valve has the disadvantages of poor corrosion resistance and easy perforation of the ordinary cast steel valve. According to the specific characteristics of the medium, the special shut-off valve for ammonia gas is made of corrosion-resistant steel on the valve body material (carbon steel is added with corrosion resistant alloying elements). ), can withstand ammonia gas, gas corrosion, low temperature can reach -40 ° C, to ensure maximum working conditions. The structure adopts the Japanese cutting valve technology, and the valve body is all made of precision casting, which effectively solves the problem that the ordinary valve of the chemical pipeline has poor sealing performance and is easy to leak.