Flash point correlation with specific gravity, refractive index, and viscosity of base oil fractions

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1 Flash point correlation with specific gravity, refractive index, and viscosity of base oil fractions 171 Asian Chemistry Letters Vol. 14, No.2 (10) Flash point correlation with specific gravity, refractive index, and viscosity of base oil fractions Dobromir I Yordanov, Aleksandar N Dimitrov, Zlatotsvet B Tsonev and Petko St Petkov University Prof. Dr. Assen Zlatarov 1 Prof. Yakimov Street, Bourgas, Bulgaria, 8010 Information on the flash point (FPOC) of base oil fractions and their mixtures is of considerable importance for estimating hazards. An attempt is made to correlate the flash point of base oil fractions with other characteristics, like specific gravity, refractive index, and viscosity. Anita Publications. All rights reserved. Keywords: viscosity, lubricant oil, specific gravity, refractive index, flash point. 1 Introduction The flash point test gives an indication of the presence of volatile components in oil, and it is the temperature to which the oil must be heated under specified test conditions to give off sufficient vapor to form a mixture which ignites in presence of direct flame. The flash point is one of the major physical properties used to determine the fire and explosion hazards of liquids. Like the boiling point of a substance, its flash point depends on the ambient pressure. There are two currently accepted methods for the measurement of the flash point value of a liquid, the closed cup test, and the open cup test. Some standard test methods are as follows: Closed cup Pensky Martens ASTM D 93 and Open cup Cleveland ASTM D 92. The open cup flash point (temperature) value is usually a few degrees greater than the closed cup flash point. The purpose of the present paper is to derive correlations of the flash point with some physicochemical properties of base oil fracions and their mixtures. 2 Experimental Fourteen base oils have been used in this study. Their physical and chemical properties are summarized in Table 1. The Flash Point Analyzer, manufactured by Walter Herzog GmbH (Germany) was used to measure the flash point of base liquid oils. The Flash Point Analyzer operated according to the standard test method, ASTM D 92. The Walter Herzog GmbH viscosity measuring system used to measure the kinematic viscosity of base oil. Specific gravity measurements were carried out using a hydrometer at a temperature of C according standard ASTM D Result and discussion The flash point increases almost linearly with the normal boiling point of the molecule. This linear relation is observed for all the different classes of hydrocarbons including paraffins, olefins, naphthens and aromatics. Determination of the boiling point for lubricants is very difficult. This is the reason to start looking for relationship between the different parameters of base oils. Using the correlation matrix identified dependent and independent variables. Corresponding author : dobromirj@yahoo.com (Dr Dobromir I Yordanov)

2 172 Dobromir I Yordanov, Aleksandar N Dimitrov, Zlatotsvet B Tsonev, and Petko St Petkov Table 1 Physical and chemical properties of base oil Viscosity Viscosity FPOC, Density at Density at Sample at 40 C, at 100 C, C C 15 C mm 2 /s mm 2 /s This correlation matrix is shown in Table 2. Table 2. Correlation matrix viscosity viscosity Density FPOC, C 40 C, mm 2 /s 100 C, mm 2 /s C viscosity 40 C, mm 2 /s 1 viscosity 100 o C, mm 2 /s Dånsity, C FPOC, C Output of the correlation matrix leads us to the correlation equations, using regressive analysis. For the first equation as independent variables we used viscosity at 40 C, viscosity at 100 C,, specific gravity at C. Equation is FPOC = A*vis 40 + B*vis C* + D*SG + E. R 2 = (1) Where: vis viscosity at 40 C or 100 C SG specific gravity refractive index For the coefficients A, B, C and D we got the values: A B C D E

3 Flash point correlation with specific gravity, refractive index, and viscosity of base oil fractions 173 Table 3 shows a comparison between measured and calculated values. The scatter of measurements is determined according to [3, 4]. Fig. 1 shows the dependence between experimental and calculated FPOC. For the second equation we used three independent variables: viscosity at 40 o C,, and specific gravity o C. Table 3. Comparison between measured and calculated values. Scatter of Abs FPOC, measurement Calculated deviance, %, C FPOC, C C deviance ± ± ± ± ± ± ± ± ± ± ± ± ± ± average 6 ± FPOC, 0 C experimental FPOC, 0C calculated FPOC Equation is Fig. 1. Comparison of experimental and calculated FPOC (Eq.1). FPOC = A* vis 40 + B* + C*SG + D R 2 = (2)

4 174 Dobromir I Yordanov, Aleksandar N Dimitrov, Zlatotsvet B Tsonev, and Petko St Petkov Where: vis viscosity at 40 C. SG specific gravity. refractive index. A B C D Table 4 shows a comparison between measured and calculated values. Table 4. Comparison between measured and calculated values. FPOC, Scatter of Calculated Abs %, C measurement FPOC, C deviance, C deviance ± ± ± ± ± ± ± ± ± ± ± ± ± ± average 6 ± The comparison of the experimental and calculated FPOC according to Eq.(2) is shown in Fig. 2. FPOC, 0 C experimental FPOC, 0C calculated FPOC Fig. 2. Comparison of experimental and calculated FPOC (Eq. 2).

5 Flash point correlation with specific gravity, refractive index, and viscosity of base oil fractions 175 For the third equation we considered viscosity at 40 C, viscosity at 100 C and specific gravity C as independent variables. The equation is FPOC = A* vis 40 + B* vis C*SG + D R 2 = (3) Where: vis viscosity at 40 C. SG specific gravity. A B C D Table 5 shows a comparison between measured and calculated values. Table 5.Comparison between measured and calculated values. FPOC, Scatter of Calculated Abs %, C measurement FPOC, C deviance, C deviance ± ± ± ± ± ± ± ± ± ± ± ± ± ± average 6 ± FPOC, 0 C experimental FPOC, 0C calculated FPOC Fig. 3.Comparison of experimental and calculated FPOC according to Equation 3.

6 176 Dobromir I Yordanov, Aleksandar N Dimitrov, Zlatotsvet B Tsonev, and Petko St Petkov The comparison of the experimental and calculated FPOC according to Eq.(3) is shown in Fig. 3. One can see that all the deduced equations give similar and reasonably high correlation coefficients. 4 Conclusions 1. The correlation of the flash point of oil fractions based on the specific gravity, refractive index, and viscosity was made. 2. The results calculated by our proposed equations predict values for the flash point within the range of dispersion of the actual magnitude. References 3. The results obtained are good enough for practical purposes. 1. George V Dyroff, Manual on Significance of Test for Petroleum Products,Fifth Edition. 2. Horng-Jang Liaw, Yi-Huah Lee, Chia-Ling Tang, Hua-Hsuan Hsu, Jia-Huey Liu. Journal of Loss Prevention in the Process Industries, 15(02) Yordanov D, Petkov P, Dimitrov Al, Gogov D, Tsonev Zl, Academical Journal Management and Education, 2(09)1. 4. Yordanov D, Petkov P, Dimitrov Al, Gogov D, Tsonev Zl, Academical Journal Management and Education, 2(09)7. [Received : ; accepted : ]