Gases or Vapours

If the discharge of a gas, hence of a compressible fluid, is to be treated the type of fluid and the type of expansion has to be accounted for. Equation (2.28) applies to an ideal gas (vid. [3]) 

R specific gas constant in J/(kg K), where R = R /M holds, i.e. the quotient of the molar or universal gas constant and the molar mass of the gas in question T absolute temperature in K 

Z compressibility factor at relief pressure and temperature (Z = 1 (ideal gas) gives conservative results) 

Starting point for the treatment is Eq. (7.2) where the difference in geodetic elevation can normally be neglected in case of gases. We then have 

It is usually assumed that the change of state is isentropic (reversibly adiabatic). Hence, one has 

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The strict definition of a phase is any homogeneous and physically distinct region that is separated from another such region by a distinct boundary . For example a glass of water with some ice in it contains one component (the water) exhibiting three phases liquid, solid, and gaseous (the water vapour). The most relevant phases in the oil industry are liquids (water and oil), gases (or vapours), and to a lesser extent, solids. 

Arc formation and extinction lakes place inside a sealed chamber, thus emitting no gases or vapours to the atmosphere, which may be a cause of fire hazard. They are the most appropriate choice for such areas... 

The density of a vapour or gas at eonstant pressure is proportional to its relative moleeular mass and inversely proportional to temperature. Sinee most gases and vapours have relative moleeular masses greater than air (exeeptions inelude hydrogen, methane and ammonia), the vapours slump and spread or aeeumulate at low levels. The greater the vapour density, the greater the tendeney for this to oeeur. Gases or vapours whieh are less dense than air ean, however, spread at low level when eold (e.g. release of ammonia refrigerant). Table 6.1 ineludes vapour density values. 

Gases or vapours that are water soluble or miscible or that are only soluble or highly reactive in other agents Absorption with multiple surface contact by atomizing liquid with spray nozzle or jet impaction Crabtree ozone analyser or midget venturi scrubber Water, acid, or alkali 5-25 60-100 Venturi scrubber satisfactory if dust is present Atomizer absorber will plug... 

Combustible gases or vapours that are not water soluble but are slowly reactive with absorbing agents Combustion and absorption Quartz or ceramic furnace with absorbers Water, acid, or alkali 1-5 90-100 Can also be used for organic halogenated fumes... 

When we come to deal with gases or vapours, we pass at once out of the region of direct applicability of Nernst s theorem. If we assume, approximately, that the specific heat of the gas is constant over a small range near the absolute zero, we have ( 79) ... 

Since few chemicals (e.g. hydrogen, methane, ammonia) have a molecular weight less than that of air, under ambient conditions most gases or vapours are heavier than air. For example, for common toxic gases refer to Table 3.1 for flammable vapours refer to Table 5.1. At constant pressure the density of a gas or vapour is, as shown, inversely proportional to the absolute temperature. As a result ... 

Theoretically, if one corner of the fire triangle is eliminated a fire or explosion is impossible. However, in practice, if flammable gases or vapours are mixed with air in flammable concentrations, sooner or later the mixture is likely to catch fire or explode because of the difficulty of eliminating every source of ignition. For reliable control of flammable materials, including combustible dusts, the aim is to remove two corners from the fire triangle. This can include some combination of ... 

Gases or vapours that are water soluble or miscible or that are only soluble or highly reactive in other agents. 

Combustible gases or vapours that are not water soluble but are slowly reactive with absorbing agents... 

Steam Distillation. Distillation of a Pair of Immiscible Liquids. Steam distillation is a method for the isolation and pimification of substances. It is applicable to liquids which are usually regarded as completely immiscible or to liquids which are miscible to only a very limited extent. In the following discussion it will be assumed that the liquids are completely immiscible. The saturated vapoiUB of such completely immiscible liquids follow Dalton s law of partial pressures (1801), which may be stated when two or more gases or vapours which do not react chemically with one another are mixed at constant temperature each gas exerts the same pressime as if it alone were present and that... 

Whether gases or vapour are evolved and their odom CA UTION )... 

Other Gas Reactions. Several other reactive gases or vapours were examined but found to be unsatisfactory. No ester formation ( 1745 cm"1) was found when oxidatized films were exposed to acetic acid or formic acid vapour. Alcohol/carboxylic acid reactions in the solid state have often been suggested as the source of ester products, but not substantiated (4,5). Gaseous ammonia reacted with carboxylic acid groups to give absorptions at 1550 cm"1 [-C(=0)-0 ] and 1300 cm"1 (NHi +). However, these absorptions were very broad and the method inferior to acid measurement by SF. Although N20 did not react with oxidized polyolefins, the reaction of N02 with oxi-... 

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