ASTM D7412 Standard Test Method for Condition Monitoring of Phosphate Antiwear Additives in In-Service Petroleum and Hydrocarbon Based Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry
12. Report
12.1 Procedure A (Direct Trend Analysis) - Values are reported in units of absorbance/0.100 mm.
12.2 Procedure B (Differential Trend Analysis) - Values are reported in units of absorbance per centimeter (Abs/cm), calculated as follows:
Phosphate Antiwear in Abs/cm = Phosphate Antiwear in Abs/0.100 mm*100
12.3 Trending - Data shall be recorded and reported at selected time intervals during the lubricant's life. Ideally, phosphate antiwear values would be compared to that of the newly formulated oil and plotted over time to visualize the relative changes in phosphate antiwear additives 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 phosphate antiwear additives are based on the type of machinery and its previous history associated with this parameter.
12.4 Statistical Analysis and Alarm Limits - For statistical analysis and setting alarm limits, refer to Practice E2412, Annex A3 on "Distribution Profiles and Statistical Analysis".
12.5 Effects ofOil Formulation - The compositions of various oil formulations can have an effect on the results reported for the phosphate antiwear 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.
13. Precision and Bias
13.1 Precision - The precision of this test method is based on an interlaboratory study conducted in 2016. Eleven laboratories tested 18 different materials. Every "test result" represents an individual determination. Each laboratory was asked to submit two replicate test results, from a single operator, for each material. Practice E691 was followed for the design and analysis of the data; the details are given in ASTM Research Report No. RR:D02-1883.
13.1.1 Repeatability Limit (r) - The value below which the absolute difference between two individual test results obtained under repeatability conditions may be expected to occur with a probability of approximately 0.95 (95 %).
13.1.1.1 Repeatability limits are estimated by the equation:
r = 0.0819x - 0.1122
where:
x = the average of two test results.
13.1.2 Reproducibility Limit (R) - The value below which the absolute difference between two test results obtained under reproducibility conditions may be expected to occur with a probability of approximately 0.95 (95 %).
13.1.2.1 Reproducibility limits are estimated by the equation:
R = 0.0621x + 2.024
where:
x = the average of two test results.
13.1.3 The above terms (repeatability limit and reproducibility limit) are used as specified in Practice E177.
13.1.4 Any judgment in accordance with statements 13.1.1 and 13.1.2 would have an approximate 95 % probability of being correct.
13.2 Bias - The procedure in this test method for measuring phosphate has no bias because the value for phosphate is defined only in terms of the test method.
14. Keywords
14.1 condition monitoring; differential trend analysis; direct trend analysis; Fourier transform infrared; FT-IR; hydrocarbon based lubricants; in-service petroleum lubricants; infrared; IR; lubricants; oils; phosphate antiwear
