n.用以遮闭之物；栓；遮断
No downstream shutoff valves are allowed. 不允许有下游关闭阀。
FLIGHT CONTROLS HYDRAULIC SHUTOFF VALVES. 飞行操纵液压关断活门。
Close the shutoff valve upstream of the regulator. 关闭调节阀上游的关断阀。
Start Up: The downstream shutoff should be closed. 启动：下游关闭阀应该处于关闭状态。
Purpose: To test shutoff #2 for tightness. 目的：检测关闭2号的紧固密封性。
