Door window should be made out of hardened glass in order to protect worker in case of leakage and broken valve.

观察门上需安装有钢化玻璃，保护操作者，防止被测地泄漏和破裂。

youdao

Door window should be made out of hardened glass in order to protect worker in case of leakage and broken valve.

观察门上需安装有钢化玻璃，保护操作者，防止被测地泄漏和破裂。

youdao