These are simply air passage.

这些都是空气的通道。

The air passage is called the air bleed.

空气通道叫通气孔。

It is used to put through cut off the air passage in vacuum pipeline.

阀门用于接通或切断真空管路中的气流。

It is used to put through or cut off the air passage in vacuum pipeline.

CC Q型气动超高真空插板阀用于接通或切断真空管路中的气流。

It is used to put through or cut off the air passage in vacuum pipeline.

阀门用于接通或切断真空管路中的气流。