screwdown valve的用法和樣例：
例句
- We strongly recommend installing a safety relief valve in addition to the unloader to add more protection from dead-heading.
我們強烈建議，除了減壓器外，再安裝安全卸壓閥來防止跑空。 - Follow manufacturers instruction regarding the installation and adjustment of any unloader and safety relief valve you choose.
按照操作守則關於你所選擇的減壓器和安全卸壓閥的安裝和調節指示。
