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Page 5b

Diesel Fuels

In the United States, diesel fuel is controlled according the American Society for Testing and Materials Standard D975-97.  This standard describes a limited number of properties that diesel fuels must meet.  It should be noted that the requirements are all performance- based.  They do not mandate the composition of the fuel, only the specific performance related requirements demanded of a fuel for a diesel engine.  The requirements of D975-97 are described below.

 ASTM Specifications for Diesel Fuel Oils (D975-97)
 Diesel fuel is characterized in the United States by the ASTM standard D 975.  This standard identifies five grades of diesel fuel described below.

Grade No. 1-D and Low Sulfur 1-D: A light distillate fuel for applications requiring a higher volatility fuel for rapidly fluctuating loads and speeds as in light trucks and buses.  The specification for this grade of diesel fuel overlaps with kerosene and jet fuel and all three are commonly produced from the same base stock.  One major use for No. 1-D diesel fuel is to blend with No. 2-D during winter to provide improved cold flow properties.  Low sulfur fuel is required for on-highway use with sulfur level < 0.05%.

Grade No. 2-D and Low Sulfur 2-D:  A middle distillate fuel for applications that do not require a high volatility fuel.  Typical applications are high-speed engines that operate for sustained periods at high load.  Low sulfur fuel is required for on-highway use with sulfur level < 0.05%.

Grade No. 4-D:  A heavy distillate fuel that is viscous and may require fuel heating for proper atomization of the fuel.  It is used primarily in low and medium speed engines.

ASTM D975 specifies the property values shown in Table 2 for these grades of diesel fuel.  The surprising aspect about ASTM D 975 is how few requirements are actually included.  The standard says nothing about the composition of the fuel or its source.  It only defines some of the property values needed to provide acceptable engine operation and safe storage and transportation.  

                    Table 2.  Requirements for Diesel Fuel Oils (ASTM D 975-97)

       

      		Grade Grade Grade   Grade   Grade
      Property LS #1 LS #2 No. 1-D   No. 2-D   No. 4-D
      Flash point °C, min 38 52 38   52    55
      Water and sediment,    % vol, max.          
      0.05 0.05 0.05    0.05  0.50
      Distillation temp., °C, 90%          
                  Min. -- 282  --    282 --
                  Max. 288 338 288    338   --
      Kinematic Viscosity,          
         mm2/s at 40°C          
                  Min. 1.3 1.9 1.3   1.9   5.5
                  Max. 2.4 4.1 2.4   4.1   24.0
      Ramsbottom carbon residue,          
      on 10%, %mass, max. 0.15 0.35 0.15 0.35 --
      Ash, % mass, max. 0.01 0.01 0.01 0.01          0.10  
      Sulfur, % mass, max 0.05 0.05 0.50 0.50          2.00  
      Copper strip corrosion,          
                  Max 3 hours at 50°C No. 3 No. 3 No. 3   No. 3   --
      Cetane Number, min. 40 40 40   40   30
      One of the following          
        Properties must be met:          
         (1) cetane index 40 40 --    --   --
         (2) Aromaticity,          
                 % vol, max 35 35 --    --   --

       





























      The       cloud point, (°C, max.) is also included in ASTM D975, however, the actual values are determined by the local climate.  Should be 6oC higher than the tenth percentile minimum ambient temperature for the region.  For Iowa the values for each month are:
                                     Month        10th % minimum temp
                                     Oct                 -2oC
                                     Nov                 -13
                                     Dec                 -23
                                     Jan                  -26
                                     Feb                 -22
                                     Mar                 -16

       

      The cloud point requirements are explained in more detail in the section on cold flow.  

      Return to What are Diesel Fuels?
       

 


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