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The purpose of this set is to test the operation of oxygen breather sets.

The panel board has the following markings:

The "+" side of the semi-circular scale is marked "Liter pro Min." and "mm"; the "-" side of the scale is marked "mm Wassersäule".

The instrument is contained in a wooden box measuring 6 x 11.2 x 9 inches, the cover being hinged at the back and 1.8 inches deep. The cover can be locked with a key and the box proper is fitted with an adjustable leather carrying strap. Inside the cover there are secured the accessories necessary for attaching the instrument to the oxygen breathing set and also a set of directions.

The scale is semi-circular in shape, the background being white and the numbers and letters black. The red pointer may be set at the zero point by means of the metal dial indicated as "NULLSTELLUNG". The red push button in the center of the panel is used for releasing the pressure in the apparatus preparatory to making a test. In the lower right corner of the panel there is a connecting fitting with a black screw cap; the marking just below this fitting "ANSCHLUSS". The apparatus is connected to the oxygen breathing the cover of the box.

Just to the left of the marking "DOSIERUNG" there is a metal pointer dial with three positions indicated by red dots on the panel: one to the left, one in the center and one to the right. When the dial is pointed to the central dot, the apparatus is closed to any external pressure and no readings can be taken; when it is pointed towards the left dot, the instrument is set for pressure readings, and when it is pointed towards the right hand dot, vacuum readings can be taken.

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