Page 42 - ebook fluid mechanics_finalize
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FLUID MECHANICS
Exercise 2
3
A pressure tube is used to measure the pressure of oil ( mass density,640 kg / m ) in a
pipeline. If the oil rises to a height of 1.2m above the centre of the pipe, what is the gauge
pressure in N / m at that point? (gravity = 9.81 m/s ) Ans: 7.55 kN/m
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3.2.2 Concepts of Barometer
Figure 3.8 : Simple Barometer
The barometer is an instrument used to measure atmospheric pressure (Figure
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3.8). Atmospheric pressure at sea level is about 101.3 kN/m , approximately equivalent to
the height of the water column 10.34 m or 760 mm mercury column height. The value of
the atmospheric pressure decreases with altitude reduction.
Pressure Barometer Mercury standard is 760mm (760mm Hg), in conjunction with
(760/1000) x 13.6 = 10:34 m of water.
Atmospheric pressure is calculated from the relationship Patm = ρgh where ρ is the
density of the fluid in the barometer. There are two types Barometer; Mercury Barometer
and Barometer Aneroid.
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