原句完整的是：Ensure that exhaust blockages cannot occur during operation, either because of mechanical components (for example, valves or blanks) or because of process materials or by-products depositing in pipelines, filters, and other exhaust components.

整篇手册中就只出现了这么一个blank，所以判断不出来。


【 在 trytry (T.T.おじさん) 的大作中提到: 】
: 个人认为这里是说blank flange。
--
FROM 58.247.164.*