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Alternative Fuels for Transportation
3.4.14 Copper Strip Corrosion
Copper strip corrosion of biodiesel is evaluated as per ASTM D130 test
method. The fuel lines of an injection system may be made of copper.
Biodiesel may contain alcohols and acids if not purified well. Hence it is
necessary to evaluate the corrosiveness of fuel. A polished copper strip is
immersed in a sample of biodiesel and heated for a specified length of time
at a specified temperature. The copper strip is removed, washed, and then
compared to the ASTM certified corrosion standards. The presence of acids
or sulfur containing compounds can tarnish the copper strip thus indicating
the possibility of corrosion.
3.4.15 Sulfated Ash
Sulfated ash is the percentage of ash by mass in the mass of a sample.
Sulfated ash in biodiesel is evaluated as per ASTM D 874. Ash that remains
after the sample has been carbonized and residue subsequently treated
with sulfuric acid and heated at 775ºC, cooled, and weighed. This ensures
the removal of catalyst (Na, K, etc.) used in biodiesel. Soluble metallic
soap, catalysts, and abrasive solids are the possible sources of sulfated ash.
Soluble metallic soaps have little effect on wear but may contribute to filter plugging and engine deposits. Abrasive solids and catalysts contribute to injector, fuel pump, piston and ring wear, and formation of engine
deposits.
3.4.16 Acid Value
Acid number is specified to ensure proper aging properties of fuel and
reflects the presence of FFAs used in the production of biodiesel. The acid
number is an important parameter when feedstocks with high FFAs are used
to produce biodiesel. The acid number is directly related to the FFA content
and oxidation stability.
Acid number is the quantity of base (mg of KOH) required for neutralizing all acidic constituents present in 1 gram of the sample. It is measured as
per EN 14104 test method. A sample dissolved in organic solvent (2.0 gm in
100 ml) is titrated against potassium hydroxide solution of known concentration and phenolphthalein as an indicator.
The acid number can provide an indication of the level of lubricant degradation while the fuel is in service. During the fuel injection process, more
fuel returns from an injector than injected into the combustion chamber of
the engine. The temperature of the return line fuel may reach more than
60ºC and thus accelerates the degradation of biodiesel. High acid value leads
to corrosion of engine parts, forms deposits in the fuel system, and affects
the life of fuel pump.
Alternative Fuels for Transportation
3.4.14 Copper Strip Corrosion
Copper strip corrosion of biodiesel is evaluated as per ASTM D130 test
method. The fuel lines of an injection system may be made of copper.
Biodiesel may contain alcohols and acids if not purified well. Hence it is
necessary to evaluate the corrosiveness of fuel. A polished copper strip is
immersed in a sample of biodiesel and heated for a specified length of time
at a specified temperature. The copper strip is removed, washed, and then
compared to the ASTM certified corrosion standards. The presence of acids
or sulfur containing compounds can tarnish the copper strip thus indicating
the possibility of corrosion.
3.4.15 Sulfated Ash
Sulfated ash is the percentage of ash by mass in the mass of a sample.
Sulfated ash in biodiesel is evaluated as per ASTM D 874. Ash that remains
after the sample has been carbonized and residue subsequently treated
with sulfuric acid and heated at 775ºC, cooled, and weighed. This ensures
the removal of catalyst (Na, K, etc.) used in biodiesel. Soluble metallic
soap, catalysts, and abrasive solids are the possible sources of sulfated ash.
Soluble metallic soaps have little effect on wear but may contribute to filter plugging and engine deposits. Abrasive solids and catalysts contribute to injector, fuel pump, piston and ring wear, and formation of engine
deposits.
3.4.16 Acid Value
Acid number is specified to ensure proper aging properties of fuel and
reflects the presence of FFAs used in the production of biodiesel. The acid
number is an important parameter when feedstocks with high FFAs are used
to produce biodiesel. The acid number is directly related to the FFA content
and oxidation stability.
Acid number is the quantity of base (mg of KOH) required for neutralizing all acidic constituents present in 1 gram of the sample. It is measured as
per EN 14104 test method. A sample dissolved in organic solvent (2.0 gm in
100 ml) is titrated against potassium hydroxide solution of known concentration and phenolphthalein as an indicator.
The acid number can provide an indication of the level of lubricant degradation while the fuel is in service. During the fuel injection process, more
fuel returns from an injector than injected into the combustion chamber of
the engine. The temperature of the return line fuel may reach more than
60ºC and thus accelerates the degradation of biodiesel. High acid value leads
to corrosion of engine parts, forms deposits in the fuel system, and affects
the life of fuel pump.