2. Should a valve need repair,
depressurize and drain the system on all sides of the valve.

如果某个阀门需要维修,则降低阀门所有端口的压力并排干系统内的流体介质。
3. Should a valve need repair,
depressurize and drain the system on both sides of the valve.

如果一个阀门需要维修,则在阀门的两侧对系统进行减压和排放。