Diesel fuel appearance

The winter period corresponds, of course, to the moment in the year where the diesel fuel and home-heating oil characteristics are noticeably different. Table 5.18 gives a typical example of tbe recorded differences heating oil appears more dense and viscous than diesel fuel, while its initial and final boiling points are higher. 

The nature of these paraffins and their concentration in diesel fuel affect the three temperatures that characterize the cold behavior. The cloud point is the temperature at which crystals of paraffins appear when the temperature is lowered. The cold filter pluming point is defined as the temperature under which a suspension no ionger flows through a standard filter. Finally, the pour point is the temperature below which the diesel fuel no longer flows by simple gravity in a standard tube. These three temperatures are defined by regulations and the refiner has three types of additives to improve the quality of the diesel fuel of winter. 

The fire ha2ard of methanol appears to be substantially smaller than the fire ha2ard of gasoline, although considerably greater than the fire ha2ard of diesel fuel. The lack of luminosity of a methanol flame is stiH a concern to some, and M85 (or some other methanol fuel with an additive for flame luminosity) may become the standard fuel for this reason. 

Poisoning of deNOx catalysts by SO2 could also be a problem since diesel fuels contain small amounts of sulfur compounds. Only a few studies deal with this subject [11-13]. It appears from the literature that for Cu catalysts the use of MFI as a support reduces the inhibition by SO2. Support effects also appear in the case of Co since Co/MFI is much less sensitive to SO2 than Co/ferrierite [13]. Since this support effect may be related to acidity, it becomes important, to investigate the influence of SO2 on the properties of Cu catalysts supported on Si02, AI2O3, MFI, BEA and unpromoted or sulfate promot Ti02 and Zr02- These latter have been reported active for deNOx [14]. 

This nephropathy has also been identified in male rats exposed to JP-5 by the oral route (see the discussion of Renal Effects in Section 2.2.2.2). This nephropathy does not appear to be induced by deodorized kerosene or diesel fuel, at least not under subchronic exposure conditions. No histopathological changes were noted in the renal system of rats or dogs exposed to up to 100 mg/m deodorized kerosene vapor for 13 weeks (Carpenter et al. 1976). No organ weight or histopathological changes of the renal system were... 

Renal lesions have been produced in mice by dermal application of JP-5 or marine diesel fuel. The inability to duplicate these lesions with intraperitoneal administration suggested that skin application, in particular the alteration of skin following repeated dermal application, was necessary to produce the renal toxicity, and that the renal effects appeared to be secondary to skin injury (Easley et al. 1982). Lymphocytic inflammation has been induced in the urinary bladder of mice with chronic dermal application of JP-5 or marine diesel fuel (NTP/NIH 1986). However, acute and intermediate dermal exposures to kerosene and JP-5, respectively, were not toxic to the renal system of mice (Upreti et al. 

Diesel-water emulsions are being studied extensively worldwide because of the impact these fuels have on reducing engine exhaust emissions, especially NOx and particulates. Although formulations vary, a typical diesel-water emulsion will contain approximately 80% to 90% diesel fuel, 10% to 15% water, and 1% to 5% of an emulsification additive mixture. The resulting fuel blend is transparent in appearance and has the typical appearance of diesel fuel. 

The minimum fuel/air ratio for ignition is analogous to the lower limit of flammability. It is important in Diesel fuel combustion because partial oxidation will occur in local regions in which the concentration of fuel is less than the minimum or lower limit, but these regions will not ignite or inflame. Consequently, products of partial oxidation giving rise to odor, and possibly deposits, will appear in the exhaust. This is discussed in a subsequent section. 

In petroleum technology, the temperature al which a waxy solid material appears as a diesel fuel is cooled. This material is harmful to engine performance. See also Petroleum. 

Diesel fuel usually has some moisture in it that affects the function of foam control additives - which must be chosen such that they are able to function in the expected range of moisture contents. The origin of the foaminess is poorly understood but silicone polyalkyleneoxide copolymers are effective defoamers as long as they are neither completely soluble in the fuel, nor absorbed and deactivated by the water. Polyoxypropylene containing copolymers appear to be the most effective. 

Some oilseeds are dried in the field with hot gases from oil burners. Copra is often dried in ovens or kilns fired by coconut shells. In each case, contamination with diesel fuel fumes or polyaromatic hydrocarbons is inevitable. The only question is to what extent. Some hydrocarbons occur naturally in plants and appear in plant products. Mineral oil contamination of vegetable oil was also associated with toxic oil syndrome (20). 

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