When installing the Series 4700, it is recommended that galvanized steel back up rings be used behind the valve flanges.

在安装系列4700夹管阀时，建议在阀门法兰后面采用镀锌钢支撑环加固。

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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PV C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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The goal is to tighten up or otherwise improve the faulty valve, called the esophageal sphincter, that lets acid reflux back into the esophagus.

FORBES: Health