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。

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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。

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