University of South Dakota Vermillion
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Here is a different design for an inexpensive, rugged, and accurate short-range manometer. Figures 1 and 2 show the manometer in filling position and ready for use. Details are given in Figure 3 (not to scale). - The manometer is constructed of 2 mm bore capillary and 10 mm od standard wall tubing.
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the mercury to rush in and shatter the closed leg. The valve seat is constructed from a piece of 6 mm glass tubing, one end of which has been ground with a glass sphere (such as is used to pack distillation columns) using carborundum. This valve seat is ring-sealed into the outlet arm, the ball is inserted, and small indentations are made just below the ball to keep it close to its seat.
I. Figure 1 .
The reservoir portion is sufficiently large so that i t is half filled when all of the mercury is in the reservoir. Thus, while the manometer is placed in a horizontal position, the legs can he evacuated (with high-vacuum pumping, if available) and heated to remove adsorbed material. While the manometer is still being pumped, it is restored to a vertical position, and it is ready for use. A small spherical check valve is placed near the outlet so that a sudden introduction of air will not cause
244 / lournol of Chernicol Education
Figure 2.
Figure 3.
