The design concept of the automatic security shutoff is a hinged door closing onto a knife-edged seat fully contained in a high-grade ductile iron body (or steel casting).

• 自动安全关断的设计原理是由内置于高品质延性铸铁?或铸钢?阀体，以铰闩的阀门闭锁在一具有刃缘的阀座上。