Viscosity
Viscosity is the property of a liquid of offering
resistance to shear or flow. Viscosity decreases with
increasing temperature. This decrease in viscosity
follows a logarithmic relationship for normal fossil
fuel. The common reference is to kinematic viscosity.
kinematic viscosity is the quotient of the dynamic
viscosity that is divided by the density. The
determination of kinematic viscosity is normally by
readings from gravity flow viscometers at standard
temperatures. Refer to ISO 3104 for the test method.
The viscosity of the fuel is significant because fuel
serves as a lubricant for the fuel system components.
Fuel must have sufficient viscosity in order to
lubricate the fuel system in both extremely cold
temperatures and extremely hot temperatures . If the
kinematic viscosity of the fuel is lower than “1.4 cSt”
at the fuel injection pump, damage to the fuel injection
pump can occur. This damage can be excessive
scuffing and seizure. Low viscosity may lead to
difficult hot restarting, stalling, and loss of
performance. High viscosity may result in seizure of
the pump.
Perkins recommends kinematic viscosities of 1.4 and
4.5 mm2/sec that is delivered to the fuel injection
pump. If a fuel with a low viscosity is used, cooling of
the fuel may be required to maintain 1.4 cSt or
greater viscosity at the fuel injection pump. Fuels with
a high viscosity might require fuel heaters in order to
lower the viscosity to 4.5 cSt at the fuel injection
pump.
Density
Density is the mass of the fuel per unit volume at a
specific temperature. This parameter has a direct
influence on engine performance and a direct
influence on emissions. This influence determines
from a heat output given injected volume of fuel. This
parameter is quoted in the following kg/m at 15 °C
(59 °F).
Perkins recommends a value of density of 841 kg/m
in order to obtain the correct power output. Lighter
fuels are acceptable but these fuels will not produce
the rated power.
Sulfur
The level of sulfur is governed by emissions
legislations . Regional regulation, national
regulations, or international regulations can require a
fuel with a specific sulfur limit. The sulfur content of
the fuel and the fuel quality must comply with all
existing local regulations for emissions.
By using the test methods ASTM D5453, ASTM
D2622, or ISO 20846 ISO 20884, the content of sulfur
in ultra low sulfur (ULSD) fuel must be below 15 PPM
0.0015%. The lubricity of these fuels must not exceed
wear scar diameter of 0.52 mm (0.0205 inch). The
fuel lubricity test must be performed on an HFRR,
operated at 60 °C (140 °F). Refer to ISO 12156-1.
Lubricity
Lubricity is the capability of the fuel to prevent pump
wear. The fluids lubricity describes the ability of the
fluid to reduce the friction between surfaces that are
under load. This ability reduces the damage that is
caused by friction. Fuel injection systems rely on the
lubricating properties of the fuel. Until fuel sulfur limits
were mandated, the fuels lubricity was generally
believed to be a function of fuel viscosity.
The lubricity has particular significance to the current
low viscosity fuel , low sulfur fuel, and low aromatic
fossil fuel. These fuels are made in order to meet
stringent exhaust emissions. A test method for
measuring the lubricity of diesel fuels has been
developed and the test is based on the HFRR method
that is operated at 60°C (140°F). Refer to ISO 12156
part 1 and CEC document F06-A-96 for the test
method.
Lubricity wear scar diameter of 0.52 mm
(0.0205 inch) MUST NOT be exceeded. The fuel
lubricity test must be performed on an HFRR,
operated at 60 °C (140 °F). Refer to ISO 12156-1.
Distillation
Distillation is an indication of the mixture of different
hydrocarbons in the fuel. A high ratio of light weight
hydrocarbons can affect the characteristics of
combustion.
Recommendation for Biodiesel
Biodiesel is a fuel that can be defined as mono-alkyl
esters of fatty acids . Biodiesel is a fuel that can be
made from various feedstock. The most commonly
available biodiesel in Europe is Rape Methyl Ester
(REM) . This biodiesel is derived from rapeseed oil .
Soy Methyl Ester (SME) is the most common
biodiesel in the United States. This biodiesel is
derived from soybean oil . Soybean oil or rapeseed
oil are the primary feedstocks. These fuels are
together known as Fatty Acid Methyl Esters (FAME) .
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Refill Capacities
Fluid Recommendations