TECHNICAL TERMINOLOGY


DIESEL FUEL TERMINOLOGY

1.      BLENDED DIESEL FUEL is a combination of #1 diesel fuel (kerosene) and #2 diesel fuel. The ratio of diesel fuel to kerosene is typically found in the range of 80:20, 70:30, 60:40, or 50:50. See Kerosene Blended Diesel Fuel Basics under Resources for additional information.  

2.      BRITISH THERMAL UNIT (BTU) is the amount of heat required to raise the temperature of 1 pound of water 1°F. The BTU is used to measure the energy content of diesel fuel. A diesel fuel with a high BTU content will produce more power and fuel economy than one with less BTU content.

3.      CETANE is the most universally accepted measure of diesel fuel ignition quality. Proper ignition during the combustion cycle is essential to optimum operation, economics, and durability.

4.      CLOUD POINT is the temperature at which wax crystals in diesel fuel begin to form which causes it to appear cloudy. Wax crystals plug fuel lines and filters. Compare to Pour Point.

5.      COLD FILTER PLUGGING POINT (CFPP) is a common test used to evaluate diesel fuel additive cold flow operability. The CFPP test involves pulling a predetermined amount of fuel through a fuel filter in a given amount of time. The temperature is gradually reduced and the fuel fails the test when it fails to pass through the fuel filter in the given amount of time. The CFPP equals the lowest temperature at which the fuel passed the test.   

6.      DIESEL FUEL is principally a blend of petroleum-derived compounds called middle distillates, which are heavier than gasoline but lighter than lube oil. Diesel fuel is combustible and used for fuel in diesel engines.

7.      FLASH POINT is the lowest temperature at which a liquid will yield enough flammable vapor to ignite. The flash point of diesel fuel varies between 100°F to 150°F. 

8.      GELLING/WAXING is a thickening of diesel fuel caused by wax crystals which form as the temperature of the fuel is reduced. Gelled/waxed diesel fuel is difficult or impossible to pump and will plug fuel filters, preventing fuel from reaching the engine.

9.      ICING is the formation of ice crystals in diesel fuel caused by free water within the fuel.  Icing occurs when diesel fuel is cooled to 32°F or below. Ice crystals will plug fuel lines and filters in the same manner as wax crystals. Compare to Gelling/Waxing.

10.  KEROSENE is a class of middle distillate diesel fuel used for blending winter diesel fuel.  Kerosene is also referred to as #1 diesel fuel. See Kerosene Blended Diesel Fuel Basics under Resources for additional information. 

11.  LOW SULFUR DIESEL FUEL (LSD) is defined by the U.S. Environmental Protection Agency as diesel fuel with a maximum sulfur content of 500 ppm (parts per million). 

12.  LUBRICITY refers to the ability of a fluid to reduce the friction and wear between two moving surfaces. Diesel fuel lubricity refers to the ability of diesel fuel to prevent wear on contacting solid surfaces found in fuel pumps and injectors. Diesel fuel with poor lubricity results in premature failure to metallic fuel system components.

13.  PHASE SEPARATION refers to a liquid mixture that has separated into two or more distinct phases. Phase separation is common in fuels contaminated with water.  Phase separated fuels perform poorly compared to fuels that are not phase separated.      

14.  POUR POINT is the temperature at which diesel fuel will no longer flow. The difference between the cloud point and the pour point is generally from 0°F to 15°F.

15.  THERMAL STABILITY refers to the ability of diesel fuel to maintain its chemical properties at high temperatures. Thermal stress (high temperatures) can cause diesel fuel to degrade and form insoluble materials that can restrict fuel flow through fuel filters and injection systems.

16.  ULTRA LOW SULFUR DIESEL FUEL (ULSD) is defined by the U.S. Environmental Protection Agency as diesel fuel with a maximum sulfur content of 15 ppm (parts per million). 

17.  WAXING/GELLING is a thickening of diesel fuel caused by wax crystals which form as the temperature of the fuel is reduced. Gelled/waxed diesel fuel is difficult or impossible to pump and will plug fuel filters, preventing fuel from reaching the engine.

DIESEL FUEL ADDITIVE TERMINOLOGY

1.      BIOCIDES eradicate fungi and bacteria commonly found in diesel fuel. Fungi and bacteria are known by a number of names including: microbes, microorganisms, microbial slime, and fuel bugs. Microbes plug fuel lines and filters and corrode metal fuel system components.

2.      CETANE IMPROVERS increase diesel fuel cetane. Cetane improvers increase power and reduce hard starting, engine noise and exhaust emissions. 

3.     COLD FLOW IMPROVERS are formulated to depress the cold temperature operability limit of diesel fuel. Diesel fuel contains wax that crystallizes in cold temperatures and plugs fuel lines and filters. Crystals in untreated fuel have relatively large flat structures and tend to stick to one another to form a lattice structure or gel. Cold flow improvers reduce crystal size to 1/10 or less of the size of untreated crystals which allows the fuel to successfully pass through the fuel system. Cold flow improvers can reduce the CFPP by as much as 35°F- 45°F. 

4.      COMBUSTION IMPROVERS improve combustion by reducing diesel fuel surface tension. Diesel fuels with high surface tension are more difficult to combust than diesel fuels with low surface tension. Better combustion results in better fuel economy and reduced emissions.   

5.      CORROSION INHIBITORS prevent oxidation (rust) on metallic surfaces from moisture and acids. Note: Microbial-induced corrosion may not be addressed by typical corrosion inhibitors. See Biocides for more information on microbial-induced corrosion.  

6.      CUMMINS L-10 INJECTOR DEPOSIT TEST is used to evaluate the effectiveness of diesel fuel additives in improving fuel injector performance. The test consists of configuring two Cummins L10 engines in tandem, connected by a drive shaft. For 125 hours, the engines alternate from power to idle in 15-second intervals, one engine pulling the other for 15 seconds, and then reversing roles. To pass, two criteria must be met.  First, there must be a flow loss of less than six percent. Flow loss indicates a loss of power from a dirty injection system. Second, there must be a CRC Rating of 10 or less. The injectors are disassembled and the carbon build-up is visually rated by a trained technician. The technician assigns a numerical score of 1 to 40 with 1 indicating a new/clean injector and 40 indicating a very dirty injector. To pass the Cummins L10 test, all six injectors must have an average CRC Rating of 10 or less.

7.      DEICERS reduce the freeze point of water that may separate from the fuel or disperse the water in such small droplets that ice crystal formation is precluded or inhibited. Iced fuel plugs fuel lines and filters. 

8.      DETERGENTS/DISPERSANTS prevent deposit formation or remove preformed deposits in the combustion chamber and on injector parts. Detergent/dispersant improve fuel economy, increase engine life, increase fuel system and fuel filter life, and reduce exhaust emissions. 

9.      DIESEL FUEL ADDITIVE is a chemical added to diesel fuel to enhance one or more of its properties.

10.  EMULSIFIERS chemically react one liquid with another liquid. An emulsion is a suspension of one substance in another substance. Emulsifiers are used to eliminate the negative effects caused by water in diesel fuel. See Emulsifiers vs. Demulsifiers under resources for more information.  

11.  LUBRICITY IMPROVERS protect against engine fuel system wear by forming a protective layer on metal surfaces. Lubricity improvers prolong the life of critical wear parts in the fuel system, reduce downtime, and reduce maintenance costs.

12.  STABILITY IMPROVERS prevent fuel degradation by preventing various chemical reactions, primarily oxidation. Oxidation results in the formation of gums and varnishes, which impact fuel system component performance.

13. WATER DISPERSANTS are used to eliminate the negative effects caused by water in diesel fuel. Water causes corrosion and premature failure of metal fuel system components, microbial growth, and fuel line and filter plugging when it freezes.