ASTM D6923 Standard Test Method for Evaluation of Engine Oils in a High Speed, Single-Cylinder Diesel Engine - Caterpillar 1R Test Procedure

12. Calculation or Interpretation of Results

12.1 Test Validity - If a test was run for 504 h according to this test method declare the test valid. If a test was not run as specified by this test method, then the test is operationally invalid. Some examples of an invalid test are:

12.1.1 Use of non-specified hardware,

12.1.2 Use of non-specified assembly methods,

12.1.3 A test run whose downtime is greater than 125 h,

12.1.4 Potentially a test that has a Quality Index (QI) value for a controlled parameter below the threshold of zero (see DACA II Report), and

12.1.5 If a test has greater than four consecutive hours without data acquisition on any controlled parameter.

12.2 A test with any control parameter QI value less than zero requires an engineering review to determine operational validity.

12.2.1 Engineering Review - Conduct an engineering review when a control parameter QI value is below zero. A typical engineering review involves investigation of the test data to determine the cause of the below zero QI. Other affected parameters may also be included in the engineering review. This can be helpful in determining if a real control problem existed and the possible extent to which it may have impacted the test. For example, a test runs with a low QI for fuel flow. An examination of the fuel flow data may show that the fuel flow data contains several over range values. At this point, an examination of the exhaust temperatures may help determine whether the instrumentation problem affected real fuel flow versus affecting only data acquisition.

12.2.1.1 For calibration tests, conduct the engineering review jointly with the TMC. For non-calibration tests, consultation with the TMC is available, but not required.

12.2.1.2 Determine operational validity based upon the engineering review, and summarize the decision in the comment section. It may be helpful to include any supporting documentation at the end of the test report. The final decision regarding operational validity rests with the laboratory.

12.3 Some examples of non-interpretable tests are:

12.3.1 If a test completes 504 h and the piston, rings, or liner exhibit distress, and

12.3.2 If the test is terminated prior to completing 504 h for reasons including purchaser request, excessive oil consumption, or piston, ring, or liner distress then consider the test non-interpretable.

12.4 Calculations - Use the same set of data for all calculations and graphs in the test report.

12.4.1 Quality Index - Calculate and plot the QI according to the instructions in Annex A2.

12.4.2 Oil Consumption - Calculate oil consumption in grams per hour over 36 h intervals. Delete the first 4 h of readings after an oil addition or shutdown from the linear regression. The linear regression technique is shown in Annex A6. Calculate the overall average oil consumption, the initial average oil consumption and EOT average oil consumption. The beginning of test oil consumption is the average of the 36 h periods from test hours 0 to 252; i.e., (36, 72, 108, 144, 180, 216, 252) h. The EOT average oil consumption is the average of the (468 and 504) h data points for a full-length test or for a short-term test it is the average of the last two data points from the oil consumption graph. Calculate the difference between the EOT and beginning of test oil consumption.

12.4.2.1 For a 36 h period including a shutdown, calculate the oil consumption as follows:

12.4.2.2 Do not include the first 4 h oil mass readings after a shutdown in the linear regression.

12.4.2.3 Calculate the linear regression for the period before the shutdown.

12.4.2.4 Calculate the linear regression for the period after the shutdown.

12.4.2.5 Calculate a time-weighted average from both regressions to obtain the oil consumption for that 36 h period. For example, a test experiences a 7 h shutdown at test hour twenty. The slope for the first 16 h period (hour 4 to 20) is 10.7 g/h, and the slope for the second 12 h period (hour 24 to 36) is 2.1 g/h. The weighted average is calculated as follows:

Weighted Average = [(10.7 g/h)(16 h) + (2.1 g/h)(12 h)]/(16 h + 12 h)