Equilibrium Vapor Concentrations

Toxic Volatile Ratio of Equilibrium Vapor Concentration over the Acute Substances Toxic Concentration (in ppm) is greater than 1000... 

Pupp, C., Lao, R.C., Murray, J. J., Pottie, R.F. (1974) Equilibrium vapor concentrations of some polycyclic aromatic hydrocarbons, arsenic trioxide (As4Os) and selenium dioxide, and the collection efficiencies of these air pollutants. Atoms. Environ. 8, 915-925. 

Toxic Volatile Ratio of Equilibrium Vapor Concentration over the Acute... 

Pupp, C., R. C. Lao, J. J. Murray, and R. F. Pottie, Equilibrium Vapor Concentrations of Some Polycyclic Aromatic Hydrocarbons, As406 and Se02, and the Collection Efficiencies of These Air Pollutants, Atmos. Environ., 8, 915-925 (1974). 

A rough guideline was used in this program for determining if a substance exists as a vapor or particulate (or both) at levels near the OSHA standard. If the ratio of the equilibrium vapor concentration at 25°C to the standard was between Q.05 and 50, then contribution from both vapor and particulate was considered. A ratio below 0.05 indicated it would probably be vapor. Frequently,... 

Airborne pesticides have been collected by a variety of techniques using filters, impingers, bubblers, solid sorbents, polyurethane foams, and combinations thereof. Sampling for pesticides in air is complicated because specific pesticides may be present as particulate or as a vapor or both, depending on the concentration of the pesticide in the atmosphere, the equilibrium vapor concentration, and the temperature (1-6). 

The problem of sampling for coexisting particulate and vaporous forms of a toxic substance, as discussed by Taylor et al. ( 7), becomes important when the OSHA environmental limit for vapor-producing particulates is low compared to the substance s vapor pressure. To determine if a mixture may be present in workplace air, a comparison of the equilibrium vapor concentration (EVC) with the OSHA standard is helpful. For a specific compound the EVC is calculated as follows ... 

Fig 6 Collection of Equilibrium Vapor Concentrations (shown outside temperature bath)... 

For any component i in a mixture, the equilibrium vapor concentration tji and liquid concentration Xi are governed by the relations ... 

The equilibrium vapor concentration in (17.60) corresponds to the concentration at the droplet surface and has been derived in Section 17.2 as a function of temperature. However, during water condensation, heat is released at the droplet surface, and the droplet temperature is expected to be higher than the ambient temperature. 

When R = (X), n must have the value no, the concentration of vapor at a great distance from the droplet. At the droplet s surface n must equal Ur, the equilibrium vapor concentration over the droplet surface. The solution to this equation is... 

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