needle valveˈni:dlvælv短语⁵²⁹⁹¹ 基本例句 n.针形阀;针状活门 Through needle valve can change the tee cross-sectional of low- flow adapter, thus changing the sample flow, and thus able to meet the requirements of toxicology sampling norms. 通过在一定的范围内人为改变低流量适配器三通旁支管的断面面积来改变采样流量，从而满足对酯类、腈类等气体采样规范的要求。 boshuo