What is the working principle of low-temperature emergency cut-off valve?

Low temperature emergency cut-off valve is Shanghai vivendi valve co. , LTD. According to the study of LNG gasification station many years manufacturing and supporting facilities, the introduction of Japan's advanced technology, combined with the actual situation of LNG gasification station in China, developed and become a new kind of LNG special safety shut-off valve. For the safety of LNG gasification station played a non-replaceable role, ensure the normal operation of all kinds of LNG gasification station, effectively avoid for causes such as leakage, frustrated major safety accidents. Product filling the specified pressure, the working principle of the cylinder piston valve open up to drive the stem, closing release of gas in the cylinder, piston under the action of the spring to drive the stem and disc downward movement, seal pressure valve seat, valve closed; Pneumatic operation, when the valve is the ambient temperature reaches the fusible metal melting temperature ( Used in cryogenic tank, cryogenic tank container of emergency cut-off valve fusible plug in 75 ℃ & plusmn; 5 ℃ should melt) , fusible plug inside the fusible metal will melt, working pressure will automatically discharge within the cylinder, piston under the action of the spring to drive the stem and disc downward movement, seal pressure valve seat, valve closed; Rotation at the top of the handwheel to drive the stem and disc upward movement, can open the valve manually.