ASTM D7111-11

Trace elemental analysis is used to indicate the level of contamination of middle distillate fuels. Trace metals in turbine fuels can cause corrosion and deposition on turbine components at elevated temperatures. Some diesel fuels have specification limit requirements for trace metals to guard against engine deposits. Trace level copper in middle distillate aviation turbine fuel can significantly accelerate thermal instability of the fuel leading to oxidation and production of detrimental insoluble deposits in the engine.

Gas turbine fuel oil Specification D2880 provides recommended upper limits for five trace metals (calcium, lead, sodium, potassium, and vanadium). Military specification MIL-F-16884J for naval distillate fuel sets requirements for maximum concentrations of the same five metals. Both specifications designate Test Method D3605, an atomic absorption/flame emission method, for the quantitative analysis of four of the metals. Test Method D3605 does not cover potassium. This test method provides an alternative to Test Method D3605, covers potassium and a number of additional elements.

There are several sources of multi-element contamination of naval distillate fuel. Sea water is pumped into the diesel fuel tanks (as ballast) to trim ships. Also, some of the oilers (fuel supply ships) have dirty tanks. Corrosion products come from unlined tanks, piping, pumps, and heat exchangers.

1.1 This test method covers the determination of selected elements in middle distillate fuels by inductively coupled plasma atomic emission spectrometry (ICP-AES). The specific elements are listed in Table 1. The concentration range of this test method is approximately 0.1 to 2.0 mg/kg. The test method may be used for concentrations outside of this range; however, the precision statements may not be applicable. Middle distillate fuels covered in this test method have all distillation fractions contained within the boiling range of 150 to 390°C. This includes, but is not limited to, diesel fuels and aviation turbine fuels.

1.2 This test method is not intended to analyze insoluble particulates. However, very small particulate matter (smaller than a micrometre) will be carried into the plasma and be included in the quantitative analysis.

1.3 This test method may give a result that is higher than the true value if an analyte is present in the sample in a form which is sufficiently volatile. For example, hexamethyldisiloxane will generate a biased high result for silicon.

1.4 The values stated in SI units are to be regarded as standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.