a blank stage怎么理解啊? 以前讨论过。 https:///viewthread.php?tid=316791 比较赞同“这个主题的背景应该是指多级泵提高扬程的方法. use of a blank stage 应该可以理解成采用空白的一级, 在必要时可以把叶轮装上提高扬程, 平时 ... the api is referring to a multistage pump with one stage a "blank" stage. this means that an extra stage is provided for in the original design, but with no impeller installed. you can then satisfy the requirements of this clause by installing an impeller into that stage at a later date. for a pump with many stages it may be that increasing the casing size to allow for larger impellers at a later stage is not feasible or cost effective, and a blank stage becomes the best alternative. 查看更多