Gasoline evaporative losses

Fuel vapor pressure, or Reid vapor pressure (RVP) is predominantiy influenced by the amount of C-4 in the fuel. California, other of the United States, and the EPA have or are restricting fuel RVP for both seasonal and areas (latitude). These restrictions greatiy reduce all gasoline evaporative losses. 

FIG. 6 Evaporative losses from gasoline-powered vehicles. 

Evaporative losses 18.428 (13.7%) Air Transfers at refineries or tankers, losses at storage facilities, and during vehicle fueling. Up to 18 grams of hydrocarbons vented to air for each gallon of gasoline used. 

Another environmentally imposed restriction on gasoline blends was to reduce vapor pressure. The restriction was imposed to control hydrocarbon evaporative losses during gasoline storage and automobile refueling. The consequence of this restriction was to reduce the amount of C4 hydrocarbons included in the gasoline blends. 

Gasoline samples must be handled with meticulous care to prevent evaporative loss and composition changes. 

Evaporation losses are a function of so many variables such as. (1) liquid or surface temperature, (2) variation in atmospheric temperature, (3) true vapor pressure of liquid, (4) volume of vapor space (how full), (5) color or reflectiveness of surface, (6) frequency of filling, (7) construction of tank, (8) degree of saturation attained in gas space, etc., that only the gross approximation indicated in Table 8-1 for a 10 R.v.p. gasoline... 

Figure 2.7 Gas clnomatogram obtained for 500 jl1 of diluted gasoline in -pentane inti O-duced by concunent eluent evaporation, using w-heptane as the co-solvent. Reprinted from Journal of High Resolution Chromatography, 11, K. Grob and E. Muller, Co-solvent effects for preventing broadening or loss of early eluted peaks when using concunent eluent evaporation in capillary GC. Part 2 w-heptane in w-pentane as an example , pp. 560-565, 1988, with permission from Wiley-VCH.

Propane shares several emissions advantages with natural gas and has some additional ones of its own. Like natural gas, propane vehicles do not have any evaporative or running loss emissions associated with the fuel. Unbumed hydrocarbons from propane are easier to oxidize in oxidation catalysts than methane, which results in low unbumed hydrocarbon emissions. Unbumed hydrocarbons from propane are also less reactive by about two-thirds compared to unbumed hydrocarbons from gasoline [1.26]. Being a gas, propane mixes very well with the air before entering the engine, resulting in low carbon monoxide emissions,... 

This explosives volatile nature can be overcome to some extent by enclosing the mixed explosive composition in something impervious to gasoline. Large trash bags would serve this purpose. The explosive would need to be used quickly, however, as this measure would not be enough to ensure the explosives loss of sensitizer to evaporation. Better explosive composition can be had, but this one would work and is powerful ... 

Results of a typical ASTM distillation test for an automotive gasoline are given in Table 13-28, in which temperatures have already been corrected to a pressure of 101.3 kPa (760 torr). It is generally assumed that percent loss corresponds to volatile noncondensables that are distilled off at the beginning of the test. In that case, the percent recovered values in Table 13-28 do not correspond to percent evaporated values, which are of greater scientific value. Therefore, it... 

Figure 6 shows data for four vehicles operated on gasoline and M85, two having an electrically heated catalyst (EHC). The two vehicles equipped with EHC both showed low values ol NMOG and estimated ozone production. These data seem to indicate that methanol vehicles result in less ozone than comparable gasoline veliides. However, the data only include exhaust emissions and not evaporative or running losses. These later sources of emissions should be lower using methanol because of the lower reactivity of the alcohols. 

Figure 2 shows one estimate of the global emissions of hydrocarbon pollutants. The total of 88 X 10 tons mainly represents petroleum-related operations—i.e., gasoline usage, 34 X 10 tons, refinery operations, 6.3 X 10 tons, petroleum evaporation and transfer losses, 7.8 X 10 tons, and... 

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