Saturated vapour concentration

Saturated vapour concentration Specific gravity Vapour density (air = 1) Solubility in water... 

The multiplicity of abiotic transformation products which have been detected for aminocarb has prompted a comparison of the anticholinesterase activity, in vivo insect toxicity and relative volatility of a series of oxidation products. Successive oxidations of the aryldimethylamino group resulted in increased toxicity whereas oxidation of the arylmethyl group or of the carbamate N-methyl group considerably reduced toxicity. Saturated vapour concentrations of the toxic transformation products were only slightly lower than the parent carbamate. 

A less widely used approach (8,9) has been to expose a surface of pesticide to an air flow under conditions of a rapid rate of air change such that the concentration of the pesticide in the air surrounding the stagnant boundary layer is far below saturation. Under these conditions the relative rates of diffusion of two pesticides will be inversely related to the square root of their respective molecular weights (Graham s law of Diffusion) and directly related to their saturated vapour concentrations in the boundary layer. 

In the absence of direct field measurements of pesticide fluxes eminating from a sprayed forest a series of suppositions may be drawn from similar observations of losses from treated agricultural crops. The volatilization of dieldrin and heptachlor from a grass pasture was characterized by rather marked diurnal variations in vertical flux intensities of both insecticides during the initial days post application (12). The authors concluded that the volatilization ceased or was greatly reduced with decreased solar radiance. Estimated relative vapour concentrations of dieldrin rapidly declined from saturation 2 hours post application to 10% by evening. This parameter reached a maximum of 30 - 40% on day 2 and 20 - 25% on day 3. Although the saturated vapour concentration of heptachlor is approximately fifty... 

Vapour inhalation values are intended for use in classification of acute toxicity for all sectors. It is also recognized that the saturated vapour concentration of a chemical is used by the transport sector as an additional element in classifying chemicals for packing groups. 

It is recognized that saturated vapour concentration may be used as an additional element by some regulatory systems to provide for specific health and safety protection. 

There were no deaths or signs of overt toxicity in animals exposed to the saturated vapour concentration of approximately 0.5 mg/L and therefore, the available data do not support classification. 

Rat > 83 ppm. (approx equal to 0.5 mg/1). 4 No deaths, clinical signs or gross lesions occurred at 83 ppm (85 ppm is stated to be the saturated vapour concentration at room temperature). 3... 

Rat Not stated 6 The animals were exposed to the saturated vapour concentration at room temperature (assumed to be 85 ppm). No deaths occurred and no signs of gross pathology were observed. 8... 

There was no evidence of adverse toxicity in a 13-week rat inhalation study at 0.43 mg/1 (approx. 72 ppm), an exposure level close to the saturated vapour concentration. No classification is justified according to GHS criteria. 

Rat Inhalation 21,41 and 80 ppm (0.12,0.24 and 0.48 mg/1) days 6-15 of gestation The substance was tested up to approximately the saturated vapour concentration. Decreases in dam body weight gain, associated with decreases in food consumption, were observed in the medium and high dose groups during the exposure period. There was no evidence of reproductive toxicity. 4... 

The concentration of a substance in the vapour phase (saturated vapour concentration, SVC) may be calculated from the SVP of the substance. This may be done to a useful level of accuracy by the simple application of the ideal gas law. Table 3 specifies the symbols and units of the parameters used in the calculation. 

Figure 4. Saturated vapour concentration vs temperature (°C) of TNT, PETN, and RDX.

The IDLH value represents a maximum vapour concentration from which a person can escape within 30 min without irreversible health damage or effects that would impair the ability to escape. Such information is clearly important in rescues and emergencies. It should be compared with the LEL and the saturated vapour concentration at the ambient temperature. Since a spark might cause an explosion in an atmosphere within the flammable range even if the IDLH is greater than the LEL, other considerations than the IDLH may prohibit entering a solvent-laden atmosphere. 

Above the normally quoted health levels, asphyxiation can take place at saturated vapour concentration (SVC) of about 150 000 ppm. A high concentration of inert gas (or CO2) used for blanketing the vapour space in a tank can also be dangerous in this way. 

It has one of the highest ratios of saturated vapour concentrations to IDLH (286 1) and an odour threshold so far above its TLV that its smell is no protection at all against an unhealthy working environment. 

The concentration C of a given substance, which can be maximally achieved at a given temperatore is the saturated vapour concentration (in mg/m ). This can be derived from the saturated vapour pressure p (a value that often can be found in the substance properties) using the following formula ... 

Eqs. (4) - (7) are solved simultaneously at a given time. Gas, liquid and solid phases have their own simulation domains interconnected with each other via corresponding boundary conditions. In the present study the equation for heat transfer (7) is connected to the vapour diffusion equation (4) by calculating the saturated vapour concentration at the liquid-gas interface as a function of local temperature. 

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