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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.
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