Frequently Asked Questions >> Test Descriptions >> Fuel Tests

Fuel Tests

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API Gravity. API Gravity is the measure of a diesel fuel’s density, or weight per volume. The higher the API Gravity, the less dense the fuel. API Gravity provides valuable information about a fuel’s composition and performance characteristics, including power economy, low temperature properties and smoking tendencies.

Ash. Ash is the noncombustible residue of a lubricating oil or fuel. Some oil detergent additives contain barium and calcium derivatives that are a common source of ash. Ash deposits can impair engine power and efficiency.

Bacterialogical Testing. Determines the presence of bacteria. Indicates that fuel storage tanks have not been properly maintained. Water can build up at the bottom of storage tanks and create a fertile breeding ground for biological growth.

Bottom Sediment & Water. The amount of sediment and water by volume which accumulates in the fuel while in service, in storage, or at delivery. BS&W in fuel can cause corrosion, wear, bacterial growth and premature fuel filter clogging. 

Carbon Residue. Coked material remaining after an oil has been exposed to high temperatures under controlled conditions.

Cetane Index. A measure of a diesel fuel’s ignition quality. The limit for a #2 diesel fuel is a Cetane Index of at least 40.

Cloud Point. Cloud Point is the temperature at which waxy crystals in an oil or fuel form a cloudy appearance. The precipitated wax clogs the fuel filter and lines to stop the fuel from reaching the engine.

Cold Filter Plug Point. CFPP is the temperature of a fuel at which wax crystals form to the extent that they plug fuel filters.

Copper Corrosion. Evaluates a fluid’s tendency to corrode cuprous metals. Results are based on the matching of corrosion stains and are often reported on a pass⁄fail basis. 

Distillation. Distillation temperature is the temperature at which 90% of the fuel volume can be distilled off. This temperature is directly related to the fuel’s volatility and therefore, its Cetane Index, density, flash point and viscosity as well.

Fire Point. Lowest temperature at which a combustible liquid must be heated so that the released vapor will burn continuously when ignited. 

Flash Point. Lowest temperature to which a combustible liquid must be so that the released vapor will momentarily ignite. A low diesel fuel flash points indicates contamination by more volatile fuels such as gasoline. Low flash indicates volatile impurities which will cause pre–ignition.

Lubricity. The ability of an oil or grease to lubricate. Also known as film strength.

Pour Point. Lowest temperature at which fuel will pour.

Specific Gravity. Ratio of the weight of a given volume of liquid to the weight of an equal volume of water. Specific Gravity can be determined using a hydrometer, a graduated float weighted at one end that provides a direct reading of specific gravity depending on the depth to which it sinks in the liquid.

Sulfur. A common natural constituent of petroleum products. Certain sulfur compounds are commonly used to improve the load–carrying properties of an oil. High sulfur content can be corrosive and create an environmental hazard when burned. Therefore, the federal government regulates the amount of sulfur in diesel fuels.

Listed below is a summary of other benefits resulting from a comprehensive oil analysis program.

  • Oil change intervals can be reduced by 20% by not discarding oil that still has useful life.
  • Help with fleet management to schedule maintenance repairs and avoid downtime.
  • Better manage budgets by forecasting the cost of repairs.
  • Develop a complete profile and history of each truck to help with evaluating performance, and planning replacement purchases.
  • Monitor maintenance schedules and practices to verify that maintenance is being done and more importantly being done on time.

This is only an overview of the cost–effective impact of oil analysis as part of any comprehensive fleet maintenance program. ANA Laboratories can assist in implementing a fluid analysis program and with training your fleet maintenance personnel to help assure the success of the program.

We look forward to the opportunity of providing this valuable maintenance tool.