| 摘要 |
A relatively simple and compact apparatus is described for producing and/or monitoring a plurality of reference pressures wherein all the pressures must be precise and, especially, precisely related to each other. The apparatus includes a plurality of manometers, each including a reservoir and an elongated vertical tube connected together at their lower ends and partially filled with a manometer liquid such as mercury. As an example, a first (lower) reference pressure such as 150 torr (150 mm Hg) is connected to the reservoir of a first manometer while a second reference pressure such as 300 torr is connected to the reservoir of a second manometer of the same construction. The liquid in the vertical tubes will be at the same level only when the second reference pressure is precisely twice as great as the first.
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