Fire Safe - Secondary metal-to-metal seal ACTS as backup if primaryseal is destroyed by fire.
防火安全-如果第一个密封被火烧坏，则第二个金属对金属密封作为后备密封发挥作用。
2
The metal diaphragms act as the seal at the top of the valve. The primary improvement in this generation of valves is the elimination of the spring used to open the valve.
金属横膈膜在阀门的顶部作为密封。这一代阀门的主要的改进是取消了用于开启阀门的弹簧。
3
BVI Business Company formation, all primary documents and corporate seal.