Fuel Terms

Fuel Terms	Description	Effects
API Gravity	A scale used to measure fuel weight	Heavy fuel is hard to burn and has a low API. Light fuel has less heat and less mpg performances, and has high API
Ash Content	Non-Combustible material	High ash means increased wear, more smoke, lost fuel
BS & W	Bottom Sediment and Water Content	Non-usable material in fuel.
BTU	The quantity of heat required to raise the temperature of one pound of water by one degree	Measure of fuel’s energy output.
Cetane	Ignition Quality (Startability)	Low cetane means poor starting. High cetane means good starting.
Cloud Point	Wax Formation Temperature (Crystals form)	Fuel at cloud point will flow but will have paraffin wax crystals suspended in fuel. This may plug filters and lines.
Conradson Carbon Residue On 10% Bottoms	Measure of fuel’s tendency to form injector deposits.	High percent means injectors stick, Increase wear, Tip deposits.
Distillation	Boiling range/lab test (Vapor temperatures)
EP	End Point	Low EP means less horse-power. High EP means more smoke, more deposits, more wear.
Flash Point	Lab test of fuel vapor flame point	Low Flash Point means probable blending with lighter products (handling danger).
Hydrogen/Carbon Ratio	Measure of fuel’s major components. Hydrogen and carbon content is used to determine the fuels BTU content (fuel economy)	Will tell the ultimate MPG the fuel will deliver when used.
IBP	Initial Boiling Point	Low IBP means lighter fuel. High IBP means hard to burn
10% 50% 90%	10% Vaporized 50% Vaporized 90% Vaporized	Same as above Same as above Same as above
Lubricity	Measure of fuel’s lubricity properties	Lack of proper lubrication will increase fuel pump and system wear
Microbial Activity (Organic)	Fungus or Bacteria spores or growth in fuel	Microbial activity causes fuel filter plugging, injector fouling, system deposits, tank and line corrosion, loss of usable fuel, lower mpg, more smoke, lower power, poor idling
Oxidation Stability	Free Carbon formation in fuel due to incompatibility	High test number means unstable fuel, engine deposits, system deposits, increased smoke, low power
Particulate Content (Inorganic)	Solid contaminants present in fuel	Higher amounts result in fuel system deposits, filter fouling, increased smoke, and loss of usable fuel. Examples: Rust, Dirt, and other foreign materials.
Pour Point	Jell Temperature (Solid Fuel)	Fuel at pour point temperatures will not flow through lines or filters. Solid in tanks
Recovery and Residue	A lab test to determine maximum usable fuel content	Recovery is a lab measurement of usable fuel. Residue is a lab measurement of unusable fuel.
Sulfur Content	Fuel contaminant which is a major element in system corrosion and fuel acidity	High sulfur means increased wear, more deposits, oil contamination, more smoke
Trace Metals	Contamination of fuel by small amounts of metal particles present in crude oil	Higher amounts mean more deposits, increased wear, decreased fuel stability, increased ash.
Viscosity	Measure of Fuel Thickness	Low viscosity can cause injector leaks and more wear. High viscosity is hard to burn and gives poor injector spray.