ASTM D4176 method for free water and particulate contamination in distillate fuel
ASTM D4176 standard test method for free water and particulate contamination in distillate fuels (visual inspection procedures)
11. Report
11.1 For field tests, the report shall provide an adequate description of the sample including the type of fuel, the source of the fuel (the sampling point), and the date, time, and approximate temperature of the sample. The report shall also indicate the approximate temperature at which the test was run and that a field test was performed.
11.1.1 For lab tests, the report shall include the test temperature at which the sample was analyzed. The report shall also indicate that a lab test was performed.
11.2 Procedure 1 - The results of the test shall be shown as pass if: (A) The sample has been found to be clear and bright on visual observance, and (B) If there is no water or particulates observed at the bottom of the vortex. The results shall be reported as fail if (A) or (B) conditions are not met. The reason for any failure should also be recorded.
11.2.1 In addition to the pass/fail reporting requirements in 11.2, the individual sample qualities may be reported as follows:
Clear and Bright - Pass or Fail
Free Water - Pass (absent) or Fail (present)
Particulates - Pass (absent) or Fail (present)
11.3 Procedure 2 - The report shall include the numerical rating of the sample and a note as to whether any particles or water droplets were found on the bottom of the sample container. Any special or unusual observations, such as darker than usual fuel color, shall also be reported.
12. Precision and Bias
12.1 Procedure 1 - It is not practical to specify the precision of the procedure because the test is a pass/fail test, not a quantitative measurement.
12.2 Procedure 2 - A rigorous precision statement cannot be developed according to ASTM Research Report D02-1007 because the intervals between the rating steps are not known to be equal. However, if the intervals are assumed to be equal, the following estimates of precision will apply. Examination of the results of a cooperative test program supports these estimates.
12.2.1 Repeatability - The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test samples would, in the long run, in the normal and correct operation of the test method, exceed one number in only one case in twenty.
12.2.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test materials would, in the long run, exceed two numbers only in one case out of twenty.
NOTE 2 - The reproducibility values above were estimated from results obtained at the same location and on the same day by different operators/instruments testing identical samples at the same time as closely as possible. The instability of typical fuel hazes introduces unpredictable variations for samples tested at different times and makes the shipment of samples to different locations impractical. The basis of this precision statement and the program comparing results obtained by this procedure by 12 operators on 24 fuel samples are available from ASTM Headquarters.
12.3 No justifiable statement can be made on the bias of either procedure in Test Method D4176 because a fuel haze can result from a number of causes and relationship with a single absolute quantitative method is not possible.
13. Keywords
13.1 cleanliness; distillate fuel; free water; particulate contamination; visual inspection; visual ratings
