General Methods for the Analysis of Physical Properties of Fuels

Abstract

This article is another in a series of articles focused on introducing general methods for evaluating conventional and alternative fuels. The text presents an overview of the physical properties determined for liquid and gaseous fuels. Additionally, methods for determining these properties are presented. The significance of individual determinations is also discussed. Emphasis is placed particularly on standardized parameters and tests, but in some cases, tests that are not required by the relevant standards are also discussed. The main goal of the article is to provide a comprehensive overview of which physical properties are monitored for each fuel, why these properties are monitored, and what methods are used for this purpose. The article provides an overview of monitored physical properties for liquid and gaseous alternative fuels. Regarding the physical properties, density at 15 °C is practically monitored for all discussed liquid fuels. Only for E95 fuel, the density at 20 °C is prescribed. Kinematic viscosity at 40 °C is monitored for all diesel engine fuels, while there are no prescribed viscosity limits for gasoline fuels. For Jet A-1 fuel, the relevant ASTM standard pre-scribes the maximum value of kinematic viscosity at -20 °C. Distillation characteristics are prescribed for all fuels except E85, E95, rapeseed oil, and FAME. It should be noted that for FAME and fuels based on vegetable oils, the simulated distillation method is often used as a complementary method. Vapor pressure is monitored for fuels containing volatile components, including E5 and E10 gasoline, E85 fuel, and LPG. Seasonal values for vapor pressure are prescribed for E5, E10, and LPG fuels, representing values for summer and winter periods. The vapor pressure of LPG is regulated by the ratio of C3 and C4 hydrocarbons in the mixture. Flash point characterizes the fuel from a fire safety perspective and is determined for petroleum-type fuels (B7-B30, FAME, SMN 30, and paraffinic diesel), as well as for rapeseed oil and E95 fuel. Except for E95 fuel, which is determined using an open cup method, all other fuels use closed cup methods. Lubricity is determined for aviation kerosene, motor diesel fuels B7 and B10, blended motor diesel fuel SMN 30, and paraffinic diesel. Low-temperature properties are determined for petroleum-type fuels, aviation kerosene, and marine fuels. The crystallization point is determined for aviation kerosene. For fuels B7-B30, FAME, SMN 30, and paraffinic diesel, prescribed values include the temperature of wax precipitation and CFPP (Cold Filter Plugging Point).