Cetane index
Encyclopedia
Cetane index is used as a substitute for the cetane number
of diesel fuel. The cetane index is calculated based on the fuel's density
and distillation range (ASTM D86). There are two methods used, ASTM D976 and D4737. The older D976, or "two-variable equation" is outdated and should no longer be used for cetane number estimation. It is, however, still required by the United States Environmental Protection Agency
(EPA) as an alternative method for satisfying its aromaticity
requirement for diesel fuel. D4737 is the newest method and is sometimes referred to as "the four-variable equation". D4737 is the same method as ISO 4264. Cetane index in some crude oil assay
s is often referred to as Cetane calcule, while the cetane number is referred to as Cetane measure.
Cetane number
Cetane number or CN is a measurement of the combustion quality of diesel fuel during compression ignition. It is a significant expression of diesel fuel quality among a number of other measurements that determine overall diesel fuel quality.- Definition :...
of diesel fuel. The cetane index is calculated based on the fuel's density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
and distillation range (ASTM D86). There are two methods used, ASTM D976 and D4737. The older D976, or "two-variable equation" is outdated and should no longer be used for cetane number estimation. It is, however, still required by the United States Environmental Protection Agency
United States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
(EPA) as an alternative method for satisfying its aromaticity
Aromaticity
In organic chemistry, Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. The earliest use of the term was in an article by August...
requirement for diesel fuel. D4737 is the newest method and is sometimes referred to as "the four-variable equation". D4737 is the same method as ISO 4264. Cetane index in some crude oil assay
Crude oil assay
A crude oil assay is essentially the chemical evaluation of crude oil feedstocks by petroleum testing laboratories. Each crude oil type has unique molecular, chemical characteristics. No crude oil type is identical and there are crucial differences in crude oil quality...
s is often referred to as Cetane calcule, while the cetane number is referred to as Cetane measure.