Useful Definitions

FAME: Fatty acid methyl esters. A mono alkyl ester of long-chain fatty acids from naturally occurring plant oils, animal fats, and recycled greases.
Fatty acid: Any of the saturated or unsaturated monocarboxylic acids that occur naturally in the form of triglycerides (or mono- or diglycerides) or as free fatty acids in fats and fatty oils.
Flash point: The lowest temperature at which vapors from a fuel will ignite when a small flame is applied under standard test conditions.
Free fatty acids: Any saturated or unsaturated monocarboxylic acids that occur naturally fats, oils, or greases but are not attached to glycerol backbones. These can lead to high acid fuels and require special processes technology to convert into biodiesel.
Hydrocarbon: A compound composed of hydrogen and carbon. Hydrocarbons can refer to fuel components and to unburned or poorly combusted components in vehicle exhaust.
Induction period: The period of time before oxidation products form as biodiesel begins to age and degrade.
Kerosene: A refined petroleum distillate of which different grades are used as heating oil, blended into diesel fuel, and as fuel for aviation turbine engines.
Lubricity: The ability of a fuel to mitigate wear on metal-metal contact surfaces.
Microbial contamination: Containing deposits or suspended matter formed by microbial degradation of the fuel.
NTDE: A new technology diesel engine manufactured after 2010, with advanced emission control systems for reduction of PM, NOx, hydrocarbons, and carbon monoxide emissions.
Oxidation: Loosely, the chemical addition of oxygen to a molecule.
Oxidative stability: The ability of a fuel to resist oxidation during storage or use.
Additive: Material added in small amounts to finished fuel products to improve certain properties or characteristics.
Antioxidant: Substance that inhibits reactions promoted by oxygen.
Biodiesel: Methyl esters of fatty acids meeting the requirements of ASTM Specification D6751.
Biodegradable: Capable of being broken down by the action of microorganisms.
Boiling range: The spread of temperature over which a fuel or other mixture of compounds distills.
Cetane index: An approximation that correlates with a diesel fuels aromatic content based on an empirical relationship with density and volatility parameters such as the mid-boiling point; widely mistaken as an approximation of cetane number. This approximation is not valid for biodiesel or biodiesel blends.
Cetane number: A measure of the ignition quality of diesel fuel based on ignition delay in an engine. The higher the cetane number, the shorter the ignition delay and the better the ignition quality.
Cloud point: The temperature at which a sample of a fuel just shows a cloud or haze due to crystals when it is cooled under standard test conditions, as defined in ASTM D2500.
Energy Conservation Reauthorization Act: The Energy Conservation and Reauthorization Act of 1998 amended EPAct to allow qualified fleets to use B20 in existing vehicles to generate AFV purchase credits, with some limitations.
Elastomer: A rubber-type material frequently used in vehicle fuel systems (but not necessarily natural or synthetic rubber; may also apply to other polymers).
Energy content: The heat produced on combustion of a specified volume or mass of fuel; also known as heating value or heat of combustion.
EPAct: Energy Policy Act of 1992. Title III provides incentives to promote the use of alternative fuel vehicles in transportation.
Oxygenate: A fuel component that contains oxygen, e.g., biodiesel or ethanol.
PM: Particulate matter. The solid or semi-solid compounds of unburned fuel that are emitted from engines.
Polyunsaturated fatty acids: Fatty acids with more than one double bond.
Pour point: The lowest temperature at which a fuel will just flow when tested under standard conditions as defined in ASTM D97.
Renewable diesel fuel: A diesel fuel most closely associated with production from the hydrotreating of renewable feedstocks, such as fats and oils.
Saturation or saturated compound: A paraffinic hydrocarbon or fatty acid, i.e., with only single bonds and no double or triple bonds.
Solvent: A liquid capable of dissolving another substance to form a solution. A solution is a homogeneous mixture composed of two or more substances.
Specific gravity: The ratio of the density of a substance to the density of water.
Splash blending: The fuels to be blended are delivered separately into a tank truck.
Stratification: Separation into layers.
Storage stability: The ability of a fuel to resist deterioration in storage due to oxidation.
Torque: A force that produces rotation.
Viscosity: A measure of the resistance to flow of a liquid.