LUBRICITY OF DIESEL FUELS BY HIGH-FREQUENCY RECIPROCATING RIG (HFRR): ASTM D6079
EXPLANATION
Diesel fuel injection equipment has some reliance on lubricating properties of the diesel fuel. Shortened life of engine components such as diesel fuel injection pumps and injectors, has sometimes been ascribed to lack of lubricity in a diesel fuel. This test method evaluates the diesel fuel lubricity using a high frequency reciprocating rig (HFRR). It is not known whether this test will predict the performance of all additive/fuel combinations. Work is underway to establish this correlation. The wear scar generated in the HFRR test is sensitive to contamination of the fluids and test materials and the temperature of the test. Lubricity evaluations are also sensitive to trace contaminants acquired during test fuel sampling and storage. The HFRR test may be used to evaluate the relative effectiveness of diesel fuels for preventing wear under the prescribed test conditions.
TEST SUMMARY
A 2-mL test specimen of fuel is placed in the test reservoir of the HFRR and adjusted to either of the standard temperatures (25 or 60° C). The preferred test temperature is 60° C unless there is concern regarding the volatility or degradation of the fuel at that temperature. When the fuel temperature has stabilized, a vibrator arm holding a nonrotating steel ball and loaded with a 200-g mass is lowered until it contacts a test disk completely submerged in the fuel. The ball is caused to rub against the disk with a 1-mm stroke at a frequency of 50 Hz for 75 min. Then the ball is removed from the vibrator arm and cleaned. The dimensions of the major and minor axes of the wear scar are measured under 100x magnification and recorded.
TEST PRECISION
This test method has a repeatability of 0.062 mm at 25° C and 0.080 mm at 60° C, and a reproducibility of 0.127 mm at 25° C and 0.136 mm at 60° C.
This test method has no bias.
