Properties of fatty oils, such as viscosity (~), iodine value (IV) and saponification value (SV), are useful in the design of methods and equipments for the processing of the fatty oils to value-added products. This investigation is aimed at the development of generalized empirical relationships based on a model similar to the Antoine equation for vapor pressure. Two equations resulted. The first equation: log ~ = [-1.4 + 1.25 (IV/SV)] + [500 -375(IV/SV)]/ [(t + 140) -85(IV/SV)] relating the logarithm of viscosity to the ratio of iodine value to saponification value (IV/SV) and temperature in degrees centigrade (t), gives an average absolute deviation of 13.0% at 77 data points of several fatty oils. The second equation, somewhat simpler in form: log ~ = -0.6298 + [273.66/(t + 88.81)] relating the logarithm of viscosity directly to the temperature in degrees centigrade (t), gives an average absolute deviation of 14.5% at 89 data points of a larger group of fatty oils ranging from almond to tallow.The two equations can be used conveniently to predict either viscosity, iodine value or saponification value, when the other two properties are known, for design purposes.The utility of fatty oils as constituents in food products, surface coating formulations, pharmaceuticals and cosmetics has been well known for a long time. To design and operate the associated unit processes and unit operations in different industries (which use the fatty oils), knowledge of at least a few physical properties is essential. Among the transport properties, viscosity (which is a measure of internal friction of the molecules) is the most important, from the point of design and process control. During polymerization and hydrogenation, the viscosity of oils increases. Changes in viscosity in such processes can be used to monitor the process, e.g., stop the polymerization or hydrogenation, at the required level. Viscosity is also influenced by changes in temperature, generally decreasing exponentially with increase in temperature.Viscosity -temperature (~/-t) relationships are of good value in programming the process control of the units for important reactions such as hydrogenation and polymerization. A careful literature survey revealed that, in spite of its importance for design and process control purposes, only Haighton and coworkers (1) studied the problem and tabulated the constants "a" and "b" of the model log ~/= a + 106b T -3[1]for 16 oils. The values of"a" and "b" tabulated by the investigators (1) for each fatty oil can be used in conjunction with equation [ 1 ] to calculate the viscosity from the absolute temperature (T) in degrees kelvin, with an aver-*To whom correspondence should be addressed.age absolute deviation of 3.2%. With the availability of more data in the compilations of Lange (2), Bailey (3) and the CRC Handbook (4), it was desirable to attempt further work on the ~-t relationships, with the twin objectives of (a) exploring the possibility of proposing interrelationships between important properties characterizing f...
