twin typesafety valve复式安全泄气阀
twin-valve双阀芯
twin type safety valve复式安全泄气阀;复式安全松气阀
twin type securety valve复式安全灰心阀
twin lobe bioprosthesis valve双叶人造生物瓣膜
valve twin-spark plug cylinder heads四气门双火花塞缸盖
twin-seat both seatsbidirectional valve双座
twin flapper-and-nozzle valve双喷嘴挡板阀