Cetane

The chemical makeup of diesel fuel will determine ignition quality of the fuel when injected into an engine cylinder. The cetane improver 2EHN (2-ethyl-hexyl-nitrate) is a liquid chemical hydrocarbon that when added to diesel fuel improves ignition quality by decreasing the fuel ignition delay time in the engine cylinders. Diesel fuel cetane performance is categorized as a number - “engine cetane number”. Higher cetane engine numbers improve ignition quality, reduce emissions, enhance engine performance and improve fuel mileage. The engine cetane number of a diesel fuel is obtained through laboratory testing using an actual diesel engine operating on the fuel compared to a known reference fuel value.

The minimum cetane engine number in the United States is 40. ASTM minimum standard for Biodiesel (B-100) is 47. Original Equipment Manufacturers (OEM’s) recommend a 50 cetane number for optimum performance. German standards require a minimum 49 cetane engine number while the European Standard is 51 minimum.

Cetane Index is a calculated number from laboratory quality tests on the diesel fuel physical properties that come from three points of the distillation test plus the fuel’s density. Cetane Index is solely dependant on the physical qualities of the diesel fuel and it is not affected by cetane improver additives. Cetane Index is used as a base for what improvements may be needed to enhance the physical ignition quality of the diesel fuel to acceptable standards.

Amalgamated^® uses 2EHN (2-ethyl-hexyl-nitrate) for its cetane ignition improver. Industry data was collected several years ago for 2EHN and an industry accepted response curve was developed. This industry Cetane Response Curve is used to determine how much 2EHN is needed to improve the engine cetane number. The reaction of diesel fuel to cetane improver additive is directly dependant on the responsiveness of the fuel. “Higher response” fuels show greater improvement in cetane numbers with the addition of 2EHN than the equivalent percentage of 2EHN in “average responding” and “lower responding” fuels.

Unfortunately, there are few (if any) “high responding” fuels and only a very limited number of “average responding” fuels in today’s market. While the response curve data is still valid, nearly all fuels available today fall into the “low response” category and most are in the mid to low part of that range. This is very important because improving a low responding fuel by 5 cetane numbers may take two to three times the amount of 2EHN as a percentage of volume that is required for a high responding fuel.

Amalgamated^® collected data over a five year period of #2-LSD from a major Midwestern United States pipeline. More than 150 samples were taken during this period and all samples had cetane engines ran on them. At the same time equivalent samples were treated with a premium additive containing cetane improver and cetane engines were ran on them as well. The same additive was used over the 5 year period during which the additive showed an average of 6+ cetane number increase.

If you are interested in improving engine operation and maximizing fuel economy, contact us today to make arrangements for sending us a sample of your diesel fuel. We can have your fuel laboratory tested to determine the amount of cetane improver needed to maximize the benefits of increased ignition quality, reduced emissions and improved engine performance.

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