back-up valve
常见例句
- Furtherly, the paper also takes the back-up equipment, concept and application for the downhole-deploymemt-valve into full research.
此外，本文还对套管阀的设备配套、理论和应用进行了较全面的分析研究。
lib.swpu.edu.cn - PVC flocking materials used by high-frequency hot press molding, gas valve back up, with both gas permeability and gas leak-proof function.
用植绒PVC料经高频热压成型，倒阀门气嘴，具有双层防漏气渗气功能。
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