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Atmosphere
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
Objects (including humans) support a column of air directly above them. This column exerts a force on such objects equal to its weight or density. This force is, on average, maximal at sea level, where atmospheric pressure is equal to a standard atmosphere, 760 mmHg or 760 torr. In the international system of units (SI), the unit of pressure is newtons per square meter, called a pascal (Pa). The pressure of the standard atmosphere in SI units is 1.01325 × 105 Pa. Many meteorologists describe atmospheric pressure in millibars (1 mbar = 100 Pa). At sea level, atmospheric pressure is 1013.25 mbar. In U.S. units, it is 29.92 in Hg and 14.7 lb/in2 (psi).
Fluid Mechanics
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
atm (Standard atmosphere): This is a unit of pressure defined as 101,325 Pa (1.01325 bar). It is sometimes used as a reference or standard pressure. It is approximately equal to the atmospheric pressure at sea level.
Introduction and Basic Concepts
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
where ρ is the density of mercury, g is the gravitational acceleration, and z is the height of the mercury column above the free surface; the effects of tube length and cross-sectional areas on the height of fluid column are negligible. Standard atmosphere is defined as the pressure produced by a mercury column of 760 mm height (or a column of water 10.3 m) at 0°C under gravitational acceleration of 9.8 m/s2.
Oxygen depletion in enclosed spaces
Published in Journal of Marine Engineering & Technology, 2020
As opposed to the methodology used in other studies, our research aims to continuously monitor the oxygen depletion process in a model. This data allows us to determine the rate of oxygen depletion. Dalton’s Law of Partial Pressures states that for a mixture of gases in any container, the total pressure exerted is the sum of the partial pressures that each gas would exert if it were alone in that container. The standard atmosphere is a unit of pressure equal to 101.325 kPa. The partial pressures of each of the air components (in kPa) are equal to the percentage of that component. With the exception of oxygen and water vapour, all constituents of air are inert or unreactive gases; therefore oxygen and water vapour are the only gases which can be consumed in the rusting process. In a closed containment experiment if all the oxygen is used up by corrosion, the pressure in the container is 80.425 kPa which is equal to the atmospheric pressure minus the partial pressure of oxygen (20.9 kPa). Table 1 shows the relationship between the Oxygen level, the absolute pressure within the container and the level of danger within the space.
Skyshine Calculations for a Large Spent Nuclear Fuel Storage Facility with SCALE 6.2.3
Published in Nuclear Technology, 2021
Georgeta Radulescu, Kaushik Banerjee, Thomas M. Miller, Douglas E. Peplow
All sensitivity calculations presented in this section used a single vertical SNF storage cask,17 the model of which is illustrated in Fig. 1. This cask model describes a canister loaded with 24 PWR SNF assemblies of identical initial enrichment (3.59 wt% 235U), average burnup (43 GWd/tonne U), and decay time (5 years). The fuel assembly materials were homogenized within the active fuel region, lower-end assembly hardware, gas plenum region, and upper-end assembly hardware. The earth-air interface was represented as a flat surface because the skyshine calculation models typically neglect local topographic features. The soil was modeled to a depth of 1 m. The base model has a cylindrical boundary with a radius of 1300 m and a height of 1301 m. Data on U.S. Standard Atmosphere18 as well as other data that were made available by various weather stations were used in this paper to determine the air density and composition at various elevations and atmospheric conditions. The U.S. Standard Atmosphere is an inert gas (i.e., dry air), static atmospheric model describing average air temperature, pressure, and density as a function of altitude. Air density primarily depends on the standard variation of air pressure with altitude and the influence of temperature variations with height on the air pressure. It should be noted that weather reports provide air pressure adjusted to sea level, not the actual atmospheric pressure at the weather station location. Therefore, the reported air pressure in weather records must be uncorrected to obtain the atmospheric pressure at the weather station location.
Study on aerodynamic characteristics and parameters of high-speed elevator car-counterweight intersection
Published in Mechanics Based Design of Structures and Machines, 2023
Xu Zhang, Ruijun Zhang, Hao Jing, Qin He
The working fluid is air with a constant temperature of 25° under atmospheric pressure. The reference pressure value is one standard atmosphere. The car, counterweight, and hoistway surface are defined as non-slip boundary conditions. The initial inlet area of the car below the hoistway and the initial inlet area of the counterweight above the hoistway adopt pressure inlet boundary conditions with a static pressure of 0 Pa, and the stopping outlet area of the car above the hoistway and the stopping outlet area of the counterweight below the hoistway adopt pressure outlet boundary conditions with a static pressure of 0 Pa.