SAE J1787:2020 pdf free

SAE J1787:2020 pdf free.Measurement of the Total Ash Content of Aviation Piston Engine Oils by a Calculation Method
The ash content as measured by ASTMD 482 has very poor precision and repeatability for lubricants having low ash content.’ The precision statement for the method states that the reproducibility of a sample in the range of 0.001 to 0.079% ash content is 0.005%. Further, the bias of the test cannot be determined and there is no standard reference material containing a known level of ash for this method.This poor precision has led to numerous problems concerning the actual ash content of products on many occasions. The test method is valuable when run by experienced operators, but can provide dubious information if run under the general conditions stated in the method. For example, to obtain repeatable results, a platinum crucible must always be used in place of the silica or porcelain crucibles listed as equivalent substitutes. Meticulous care and procedural knowledge must be used by experienced operators for the method to be productive.
The notes provided in ASTM D 482 also suggest that this method may not be appropriate for oils containing ashless additives or for oils containing certain phosphorous compounds which may now be in use in aviation lubricants. For oils containing additives an alternate method, ASTM D 874, is suggested. However, ASTM D 874 includes additional restrictions and reservations which question the suitability of that method as an acceptable alternate or replacement for ASTM D 482 for low ash containing lubricating oils.
These contradictions have led to the development of a“calculated ash content” method as a recommended alternative for use with aviation piston engine oils. This procedure is based on the ideal conversion of selected metallic elements to their theoretical oxide weights and then summing the components to obtain a total value. The seven metallic elements chosen were selected as being those most likely to be present in lubricant manufacturing and packaging plants. As such they would also be the most likely contaminants to be found in the aviation lubricants specified.SAE J1787 pdf free download.