Search results
Results from the WOW.Com Content Network
Thus one torr is exactly 101325 / 760 pascals (≈ 133.32 Pa). Historically, one torr was intended to be the same as one "millimeter of mercury", but subsequent redefinitions of the two units made the torr marginally lower (by less than 0.000015%). The torr is not part of the International System of Units (SI).
Torr Pound per square inch (Pa) (bar) (at) (atm) (Torr) (lbf/in 2) 1 Pa — 1 Pa = 10 −5 bar 1 Pa = 1.0197 × 10 −5 at 1 Pa = 9.8692 × 10 −6 atm 1 Pa = 7.5006 × 10 −3 Torr 1 Pa = 0.000 145 037 737 730 lbf/in 2: 1 bar 10 5 — = 1.0197 = 0.986 92 = 750.06 = 14.503 773 773 022: 1 at 98 066.5: 0.980 665 — 0.967 841 105 3541: 735.559 ...
For example, IUPAC has, since 1982, defined standard reference conditions as being 0 °C and 100 kPa (1 bar), in contrast to its old standard of 0 °C and 101.325 kPa (1 atm). [2] The new value is the mean atmospheric pressure at an altitude of about 112 metres, which is closer to the worldwide median altitude of human habitation (194 m).
Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth.The standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325 Pa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, [1] 760 mm Hg, 29.9212 inches Hg, or 14.696 psi. [2]
The standard atmosphere was originally defined as the pressure exerted by a 760 mm column of mercury at 0 °C (32 °F) and standard gravity (g n = 9.806 65 m/s 2). [2] It was used as a reference condition for physical and chemical properties, and the definition of the centigrade temperature scale set 100 °C as the boiling point of water at this pressure.
One torr equals the pressure necessary to raise a 1 mm column of mercury 1 mm high at 0°C against the standard acceleration of gravity at 45° north latitude (980.6 cm * s -2). One standard atmosphere equals 760 torr. The barometric reading varies with changing weather conditions and becomes lower with increasing altitude.
The current depends on the number of ions, which depends on the pressure in the gauge. Hot cathode gauges are accurate from 10 −3 Torr to 10 −10 Torr. The principle behind cold cathode version is the same, except that electrons are produced in the discharge of a high voltage. Cold cathode gauges are accurate from 10 −2 Torr to 10 −9 ...
1 torr ≈ 1 mmHg [34] ±200 Pa ~140 dB: Threshold of pain pressure level for sound where prolonged exposure may lead to hearing loss [citation needed] ±300 Pa ±0.043 psi Lung air pressure difference moving the normal breaths of a person (only 0.3% of standard atmospheric pressure) [35] [36] 400–900 Pa 0.06–0.13 psi