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The use of an actual column of mercury to measure pressure normally requires correction for the density of mercury at the actual temperature and the sometimes significant variation of gravity with location, and may be further corrected to take account of the density of the measured air, water or other fluid.
Mercury is a useful material to use in a manometer because of its high density. This means that a much shorter column is needed compared to water. [ 2 ] For instance, the pressure represented by a column of 100 mm of water is just under 7.4 mm of mercury ( mmHg ).
1 Torr = 0.999 999 857 533 699... mmHg; 1 mmHg = 1.000 000 142 466 321... Torr; The difference between one millimeter of mercury and one torr, as well as between one atmosphere (101.325 kPa) and 760 mmHg (101.3250144354 kPa), is less than one part in seven million (or less than 0.000015%). This small difference is negligible for all practical ...
So, for example, pressure head might be written "742.2 mm Hg" or "4.2 in H 2 O at 59 °F" for measurements taken with mercury or water as the manometric fluid respectively. The word "gauge" or "vacuum" may be added to such a measurement to distinguish between a pressure above or below the atmospheric pressure.
Technical literature can be confusing because many authors fail to explain whether they are using the ideal gas constant R, or the specific gas constant R s. The relationship between the two constants is R s = R / m, where m is the molecular mass of the gas. The US Standard Atmosphere (USSA) uses 8.31432 m 3 ·Pa/(mol·K) as the value of R.
Blood pressure fluctuation (40 mmHg) between heartbeats for a typical healthy adult [44] [45] 6.3 kPa 0.9 psi Pressure where water boils at normal human body temperature (37 °C), the pressure below which humans absolutely cannot survive (Armstrong limit) [46] +9.8 kPa +1.4 psi Lung pressure that a typical person can exert (74 mmHg) [47] 10 4 Pa
Research has shown that drinking beetroot juice can help lower your systolic blood pressure by four to five mmHg. Try adding beetroot juice to your diet, and if you buy store-bought juice, make ...
This validated his belief that air/gas has mass, creating pressure on things around it. The discovery helped bring Torricelli to the following conclusion: We live submerged at the bottom of an ocean of the element air, which by unquestioned experiments is known to have weight. This test was essentially the first documented pressure gauge.