Vacuum Gauge: Flattened Curved Tube Driving an Index (Bourdon, US 9,163)

A vacuum gauge shows how far a line or vessel has been pumped below atmospheric pressure. Eugène Bourdon (US 9,163, 1852) found that a thin metal tube, flattened and bent into a curve, straightens a little under internal pressure and curls up more when the air is drawn out of it. One end is open to the line through a cock; the closed end drives a lever on a spindle that carries the index. With the air withdrawn the index moves the opposite way to a pressure gauge, "and the instrument is then a vacuum gage." Source: E. Bourdon, "Pressure-Gage", US Patent 9,163 (1852). Picture: its Figs. 1-6.

上級者

Unknown

手順

Read Bourdon

"If the air be withdrawn from the interior of the tube A by means of an air pump or otherwise the curvature of the tube is increased and the index moves in the opposite direction and the instrument is then a vacuum gage."

Make the tube

Flatten a thin metal tube so its section is no longer round (Bourdon draws oval, flat, cross and Y sections) and bend it into a near circle. Close one end (how is not given) and leave the other open. Bourdon: the wall depends on the size, motion, pressure and metal; his only figure is brass about 1/100 in. thick for a barometer about 4 in. across. The metal, wall and size for the vacuum gauge are not given.

このステップの材料:

不明な金属1 tube

必要な工具:

不明な成形方法

不明な寸法

Fit the movement

Fix the open end of the tube in the case, connected through a cock to a pipe to the line or vessel. Join the closed end by a link to a short lever on a small spindle that carries the index (or drive the spindle by a toothed sector and pinion, or by a silk thread wound round it and kept tight by a spring). The lever multiplies the tube's movement at the index.

このステップの材料:

不明なバルブ1 cock

不明な金属1 link, lever, spindle and index

不明な金属1 case

必要な工具:

ボール盤

ドリルビットセット

やすり（手やすり）

Graduate the dial

Fit a dial behind the index. Bourdon graduates the arc by submitting the instrument to known pressures alongside an ordinary mercury gauge and marking each on the dial; equal steps of pressure give nearly equal degrees. Connect the gauge to a pump drawing the air out: the tube curls more and the index moves the opposite way to a pressure gauge. The reference used to mark a vacuum scale is not given.

このステップの材料: