ASTM D7844 Standard Test Method for Condition Monitoring of Soot in In-Service Lubricants by Trend Analysis using Fourier Transform Infrared (FT-IR) Spectrometry
11. Reporting
11.1 Trending - Data shall be recorded and reported at selected time intervals during the lubricant's life. Ideally, soot values would be compared to that of the newly formulated oil and plotted over time to visualize the relative changes in soot and to determine when there needs to be an oil change, albeit other parameters may dictate this change earlier. Sampling and reporting time intervals for soot are based on the type of machinery and its previous history associated with this parameter.
11.2 Statistical Analysis and Alarm Limits - For statistical analysis and setting alarm limits, refer to Standard Practice E2412, Section A3, "Distribution Profiles and Statistical Analysis".
11.3 Effects of Oil Formulation - The compositions of various oil formulations can have an effect on the results reported for soot value, and values from two different oil formulations should not be compared. Results should be interpreted relative to values measured for unused oils of the same formulation or trended directly from the sample history.
12. Precision and Bias
12.1 Precision - The precision ofthe test method has not yet been determined by formal interlaboratory study. Preliminary examinations of repeatability have shown that the difference between repetitive results obtained by the same operator in a given laboratory applying the same test method with the same apparatus under constant operating conditions on identical test material within short intervals oftime would in the long run, in the normal and correct operation ofthe test method, exceed the following values only in one case in 20:
repeatability = 0.90 absorbance units/0.100 mm for Procedure A (direct trend analysis)
repeatability = 0.86 absorbance units/cm for Procedure B (differential trend analysis)
12.1.1 The reproducibility of this test method is being determined and will be available on or before May 1, 2018.
12.2 Bias - The procedures in this test method have no bias because the soot values can be defined only in the terms of the test method and no accepted reference method or value is available.
13. Keywords
13.1 condition monitoring; differential trend analysis; direct trend analysis; Fourier transform infrared; FT-IR; hydrocarbon based lubricants; infrared; in-service petroleum lubricants; IR; lubricants; oils; soot
