Intercept the fluid medium upstream of the valve to be inspected with a shut-off valve and ensure that the subject valve is not under pressure (vent downstream, if necessary).

截取阀门上游的流体介质，用一个关闭阀门来进行检测，确保相关的阀门不处在压力下(如果必要的话，排除下游的流体介质)。

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Series 7 should be installed downstream of the water meter and of the water pressure regulator.

系列7应该安装在水表和水压力调节器的下游。

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And the ball must contain an adequate vent to the pressure port opposite of the downstream sealing port.

球体必须包含一个能够排出到下游密封端口的反面的压力端口处。

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Heavy rains and flooding in states up river in the past week, are exerting enormous pressure downstream.

VOA: standard.2010.05.09

In 1927, as floodwaters threatened New Orleans, a self-appointed committee of businessmen persuaded the government to dynamite a downstream levee and release the pressure of the swelling torrent.

FORBES: American Pyramids

Oilfield services names like Schlumberger and Baker Hughes delivered weak third quarter performance as they experienced margin pressure, while Chevron has felt the heat on tough up and downstream operations.

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