Open vent needle valve and bleed air from hose. Then close vent valve.
开启排气针形阀，并从软管排放空气。然后关闭排气阀。
Vent the piping and test valve body cavity to remove air or steam.
排放管道和试验阀门体腔内的空气或蒸汽。
Open needle valve "b" to bleed air and then close "b" and vent needle valve.
开启针形阀“B”排放空气，然后关闭“B”和排气针形阀。
Open valve a to vent air from the vent hose.
开启阀门A从排气软管处排出空气。
Open valve a to vent air from the vent hose.
开启阀门A从排气软管处排出空气。
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