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Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude. The change of atmospheric pressure with altitude can be obtained from this equation: [2]
mg/m 3 = milligrams of pollutant per cubic meter of air at sea level atmospheric pressure and T: ppmv = air pollutant concentration, in parts per million by volume T = ambient temperature in K = 273. + °C 0.082057338 = Universal gas constant in L atm mol −1 K −1: M = molecular mass (or molecular weight) of the air pollutant
However, the names of all SI mass units are based on gram, rather than on kilogram; thus 10 3 kg is a megagram (10 6 g), not a *kilokilogram. The tonne (t) is an SI-compatible unit of mass equal to a megagram (Mg), or 10 3 kg. The unit is in common use for masses above about 10 3 kg and is often used with SI prefixes.
Using atmospheric pressure as reference is usually signified by a "g" for gauge after the pressure unit, e.g. 70 psig, which means that the pressure measured is the total pressure minus atmospheric pressure. There are two types of gauge reference pressure: vented gauge (vg) and sealed gauge (sg).
= 46 kg/kmol = 46 g/mol Flow rate of flue gas = 20 cubic metres per minute = 20 m 3 /min The flue gas exits the furnace at 0 °C temperature and 101.325 kPa absolute pressure. The molar volume of a gas at 0 °C temperature and 101.325 kPa is 22.414 m 3 /kmol.
δP is the pressure drop across the bed, Pa l is the cylinder length, m η is the air dynamic viscosity, Pa·s Q is the flowrate, m 3 ·s −1. It can be seen that the specific surface is proportional to the square root of the ratio of pressure to flow. Various standard methods have been proposed: Maintain a constant flowrate, and measure the ...
Mass (kg): A 1-euro coin weighs 7.5 g; [27] a Sacagawea US 1-dollar coin weighs 8.1 g; [28] a UK 50-pence coin weighs 8.0 g. [29] Time (s): The use of minutes and hours instead of kilo and mega seconds: A second is 1 / 60 of a minute, which is 1 / 60 of an hour, which is 1 / 24 of a day, so a second is 1 / 86 400 ...
In the metric system, a microgram or microgramme is a unit of mass equal to one millionth (1 × 10 −6) of a gram.The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and United Kingdom when communicating medical information is mcg.