这些程序必须包括充分的净化和抽空时间，以允许适当清洁阀门内部。

These procedures must incorporate adequate purge and evacuation times to allow the valve interior to be properly cleaned.

youdao

真空管是一种内部气体全部或部分抽空的电子管，从而使电子在不受或少受气体分子的干扰下运动。

The vacuum tube is an electron tube from which all or most of the gas has been removed, permitting electrons to move with no or low interaction with any remaining gas molecules.

youdao