Temperature flow property

This wax can accumulate on fuel filter media and can lead to plugging of small orifices and lines. This plugging temperature can be measured and is commonly referred to as the filter plugging temperature. Testing methods utilized to predict the filter plugging temperature and the low-temperature flow properties of distillate fuel are listed in TABLE 4-5. 

As a general rule, low-molecular-weight aromatic compounds help to improve the low-temperature flow properties of fuels and oils. 

Dunn, R. O., Shockley, M. W., and Bagby, M. O. 1996. Improving the Low-Temperature Flow Properties of Alterative Diesel Fuels Vegetable Oil-Derived Methyl Esters. J. Am. Oil Chem. Soc., 73,1719-1728. 

Lubricants Mineral-based lubricants lead the lubricant market. However, with the advancement of the need for biodegradable products, vegetable oils have become popular, because of they are also better lubricants. The fatty acid composition of vegetable oils, however, is one major disadvantage. Oils rich in saturated fatty acids have poor low-temperature flow properties, and those rich in polyunsaturated fatty acids are of low oxidative resistance. Vegetable oils rich in monoun-samrated fatty acids have optimum oxidative stability and low-temperature properties (125). 

Fatty acid methyl esters and other esters of fatty acids and a lower alcohol can be added at a low ratio to most diesel fuels without substantially changing fuel characteristics. It has been reported that in blends containing 30 percent biodiesel, low-temperature flow properties are not greatly affected (12), but at higher blend levels, the properties of the methyl ester may affect the properties of the fuel. With few exceptions, pure biodiesel does not meet minimum low-temperature requirements and may exceed manufacturers maximum viscosity for diesel fuels. 

In the majority of cases, chemical additives are used to enhance the properties of base oils to improve such characteristics as oxidation resistance (ASTM D-2893, ASTM D-4742,ASTM D-5846) change in viscosity (ASTM D-445, IP 71) with temperature, low-temperature flow properties as derived from the pour point (ASTM D-97, ASTM D-5853, ASTM D-5949, ASTM D-5950, ASTM D-5985, IP 15) and fluidity measurements (ASTM D-6351), emulsifying ability (ASTM D-2711), extreme pressure (ASTM D-2782, ASTM D-2783, ASTM D-3233, IP 240), antiwear and frictional properties (ASTM D-5183, ASTM D-6425), and corrosion resistance (ASTM D-4636). The selection of components for lubricating oil formulation requires knowledge of the most suitable crude sources for the base oils, the type of refining required, the types of additive necessary, and the possible effects of the interactions of these components on the properties of the finished lubricating oil. 

Stambaugh, R.L. and O Mara, J.H. (1982) Low temperature flow properties of engine oils. SAE Trans. 91 Paper 820509. 

F ow P/LOpcAtlei Under this heading come the viscosity of the fluid and the effect of temperature on viscosity. The latter might be a theoretically derived function, or an arbitrary function such as the viscosity index, or even a grossly empirical evaluation of the viscosity at two or more selected temperatures. Low temperature flow properties are frequently evaluated by the ASTM pour point determination [5], but the inadequacies of this method of evaluation have led to the use of pumpability tests which have a better empirical relation to service conditions. 

Uses. A marked improvement in the low temperature flow property of a fuel oil having a bp 120-150°C by adding a novel compound prepared by reacting pri-, sec- or tert-aliphatic amine containing alkyl group of 1-30 C-atoms with 9,10-dihydroanthracene-9,10-endo-aP-succinic anhydride (or acid) there of together with a polymer having ethylene structure present relates compound temperature fluidity middle distillate composition petroleum fuel. 

Another early application that demanded the use of synthetic lubricants came in the mid-1960s during oil drilling in Alaska where conventional mineral oil lubricants solidified and could uot function in the severe Alaskan cold weather. Initially, a synthetic lubricant based on an alkylbenzene base stock of excellent low temperature flow properties was used in the field. This base stock was soon replaced by another base stock with better overall properties, namely polyalphaolefins (PAO). 

XI.1.1 The low-temperature flow properties of a waxy fuel oil depend on handling and ston conditions. Thus, they may not be truly indicated by pour point. The pour point test does not indicate what haqppens when an oil has a considerable head of pressure behind it, such as when gravitating from a storage tank or being pumped along a pipeline. Failure to flow at the pour point is normally attributed to the separation of wax from the fuel however, it can also be due to the effect of viscosity in the case of very viscous fuel oils. In addition pour points of residual fuels are influenced by the previous thermal history of the specimens. A loosely knit wax structure built up on cooling of Ae oil can be normally broken by the application of relatively little pressure. 

XI. 1.2 The usefulness of the pour point test in relation to residual fuel oils is open to question, and the tendency to regard the pour point as the limiting temperature at which a fuel will flow can be misleading. The problem of accurately specifying the handling behavior of fuel oil is important, and b use of the technical limitations of the pour point test, various pumpability tests have been devised to assess the low-temperature flow characteristics of heavy residual fuel oils. Test Method D 3245 is one such method. However, most alternative methods tend to be time-consuming and as such do not find ready acceptance as routine control tests for determining low-temperature flow properties. One method which is relatively quick and easy to perform and has found limited acceptance as a go-no-go method is based on the appendix method to the former Test Method D 1659 - 65. The method is described as follows. 

Besides CP (ASTM D2500) and PP (ASTM D97), two test methods for the low-temperature flow properties of conventional DF exist, namely the low-temperature flow test (LTFT used in North America ASTM D4539), and cold filter plugging point (CFPP used outside North America for example the European standard EN 116) (CEN). These methods have also been used to evaluate biodiesel and its blends with No. 1 and No. 2 conventional DF. Low-temperature filterability tests were stated to be necessary because of better correlation with operability tests than CP or PP (Owen and Coley, 1995). However, for fuel formulations containing at least 10 vol% methyl esters, both LTFT and CFPP are linear functions of CP (Dunn and Bagby, 1995). Additional statistical analysis showed a strong 1 1 correlation between LTFT and CP (Dunn and Bagby, 1995). 

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