Common air

The preceding conclusion is easily verified experimentally by arranging two bubbles with a common air connection, as illustrated in Fig. II-2. The arrangement is unstable, and the smaller of the two bubbles will shrink while the other enlarges. Note, however, that the smaller bubble does not shrink indefinitely once its radius equals that of the tube, its radius of curvature will increase as it continues to shrink until the final stage, where mechanical equilibrium is satisfied, and the two radii of curvature are equal as shown by the dotted lines. 

The effects of atmospheric pollution are chemical, and concentration, specific. However, additive, and sometimes synergistic, effects arising from mixtures are important. A sutmuary of the potential effects of common air pollutants is given in Table 16.10. 

Steelmaking is a sophisticated and complex process, with many secondary production operations, each having unique air pollution problems to varying degrees. Figures 10, 11, and 12 provide some examples of common air pollution problems. 

Volatilization — Volatilization is a physico-chemical phenomenon of particular interest to environmental managers as well as safety managers. It is the tendency of a material to transfer from a liquid phase (either pure or dissolved as in aqueous systems) to a gaseous phase (commonly air). The volatilization, or evaporation as it is more commonly called, is controlled by a number of factors, the most important of which are the vapor pressure of the material, temperature (vapor pressure increases with temperature), and air/material interfacial surface area, and the action of active mass transfer agents such as wind. 

Criteria Air Pollutant a group of very common air pollutants regulated by EPA on the basis of criteria, and for which a National Ambient Air Quality Standard is established (SOj, NOj, PM,q, Pb, CO, O3). 

The target level procedure was applied to 16 common air contaminants (Table 6.19). These are common contaminants in the industrial environment, and in many cases are the most critical compounds from the viewpoint of need for control measures. The prevailing concentration data as well as the benchmark levels were taken from Nordic databases, mainly the Finnish sources, and described elsewhere.In addition, a general model for assessing target values for other contaminants is presented in the table. 

TABLE 6.19 A Classification Scheme of Target Leveis for Common Air Contaminants in Industrial Settings... 

Pollutant load Room height Heat load Human activity level Common air supply methods Type of process... 

Common air inlet manifold conducts air from turbochargers to each power cylinder. 

MnOi- He called the gas vitriol air and reported that it was colourless, odourless and tasteless, and supported combustion better than common air, but the results did not appear until 1777 because of his publisher s negligence. Priestley s classic experiment of using a burning glass to calcine HgO confined in a cylinder inverted over liquid mercury was first performed in Colne, England, on 1 August 1774 he related this to A. L. Lavoisier and others at a dinner party... 

A house is a complex system of interacting parts that contribute to overall performance including comfort, energy use, health, maintenance, and longevity. For example, a common air distribution system utilizes supply ducts running through the attic and return ducts tied directly to the air handler inside the home. If the ductwork is not properly sealed and there are combustion appliances in the home, this configuration can lead to health and fire hazards because the... 

The most common air-pollution descriptor is the expression smoke . For the purposes of the 1956 and 1968 Acts, smoke includes soot, ash, grit and gritty particles emitted in smoke. Smoke is intended to mean the visible products of combustion and not the invisible ones (CO2, SO2, NOx, etc.) and is used to indicate the degree of completeness of combustion (if combustion is 100 per cent smoke is produced). 

The most common methods for trapping pesticide vapors from air use adsorbents. Common air sampling adsorbents include charcoal (derived from petroleum or coconut) and synthetic polymeric materials, such as cross-linked polystyrene and open-cell polyurethane foam. Charcoal has been used for the cumulative sampling of volatile... 

Common Air Pollutants from Pulp and Paper Processes... 

Table 6. Human health effects of the common air pollutants.

The size of the unit must not be bigger than 0.25 m (w) x 0.25 (d) x 0.35 m (h), which are the dimensions of common air purifiers of similar capacity. The appliance must weigh less than 10 Kg and should have lockable caster wheels for ease of transport around the house. An ergonomic and user-friendly read-out and control units will be provided to indicate the room s air quality and appliance operation. 

Jacobs, M. B. Table A-8. Concentrations of common air pdlutants in the average urban area, p. 413. In The Chemical Analysis of Air Pollutants. New York Interscience., 1960. 

On the S of this month [March, 1775] I procured a mouse, and put it into a glass vessel, containing. . . the air.. . Had it been common air, a full-grown mouse, as this was, would have lived in it about a quarter of an hour. In this air, however, my mouse lived a full half hour and though it was taken out seemingly dead, it appeared to have been only exceedingly chilled for, upon being held to the fire, it presently revived, and appeared not to have received any harm from the experiment. 

For my further satisfaction I procured another mouse, and putting it into more air.. . it lived three quarters of an hour. However, as it had lived three times as long as it could probably have lived in the same quantity of common air, and I did not expect much accuracy from this kind of test, I did not think it necessary to make any more experiments with mice.. . ... 

After some months Priestley began to think it possible that the new "air" he had obtained from calcined mercury might be fit for respiration. To his surprise he found that a mouse lived in this air much longer than in common air the new air was evidently better, or purer, than ordinary air. Priestley measured what he called the "goodness" of the new air, by a process of his own devising, and concluded that it was "between four and five times as good as common air."... 

The specific gravity of this air was found to differ very little from that of common air, of the two it seemed rather lighter. It extinguished flame, rendered common air unfit for making bodies burn, in the same manner as fixed air, but in a less degree. . . (II). 

The Honourable Mr. Cavendish favoured me [said he] with an account of some experiments of his, in which a quantity of common air was reduced from 180 to 162 ounce measures, by passing through a red-hot iron tube filled with the dust of charcoal. This diminution he ascribed to such a destruction of com-... 

Priestley also observed that lime-water never became turbid by the calcination of metals over it, and that when this process was made in quicksilver, the air was diminished only one-fifth and upon water being admitted to it, no more was absorbed (12). He stated that this air in which candles, or brimstone, had burned out. .. is rather lighter than common air (12). Thus Priestley recognized, even at this early date, some of the most important properties of the gas now known as nitrogen. 

Certain experiments [said he] appear to show. . . that it consists of atmospheric air in union with phlogistic material for it is never produced except from bodies which abound in inflammable parts, the phlogiston ever appears to be taken up by other bodies, and is hence of value in reducing the calces of metals. I say from phlogistic material, because as already mentioned, pure phlogiston, in combination with common air, can be seen to yield another kind of air. . . (25). 

Similar to Black, Daniel Rutherford (1749-1819) studied gases for his medical degree dissertation. Rutherford found that common air contained a part that supported respiration and a part that did not. Initially, Rutherford assumed the part that did not support respiration was contaminated by fixed air. Rutherford experimented and removed the fixed air, and he discovered the uncontaminated air still did not support life or combustion. Rutherford assumed the gas he had isolated was ordinary air saturated with phlogiston hence, it was phlogisticated air, which he referred to as noxious air. What Rutherford had isolated was nitrogen, and he is given credit for its discovery. 

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