1. Set Zero
2. Read Height
Using the mercury column barometer located near the wind tunnel, measure
the value of atmospheric pressure for the tunnel in centimeters of Mercury.
Convert the manometer reading to the required units of
Kilopascals.
The measurement is
carried out by first setting the mercury reservoir level to match the zero height pointer.
(1).
This is accomplished by rotating the screw thread located at the very bottom
of the manometer to raise or lower the reservoir. When the pointer just
touches the mercury surface, the column has been zeroed.
Next slide
the measuring scale
to align with the top of the mercury meniscus in the upper part of the column
(2) and read the height from the etched scale.
The height is read from the left hand scale in cm Hg with fractional increments calculated
using the nearest match on the vernier scale.
For the barometric pressure shown on the right the reading would be
77.06 cm Hg
this converts to 102.7 KPa.
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