Development and Verification of the HFRR test for automotive diesel fuels

The drive towards lower sulphur levels in automotive gasoils (AGOs) has led to a reduction in fuel lubricity, and many low sulphur (<500 mg/kg) base fuels require additive treatment for them to afford adequate protection to the moving surfaces of more sensitive fuel injection equipment.

A collaborative ISO/CEC work programme, carried out in 1994, identified the HFRR (high frequency reciprocating rig) test as a suitable means of assessing AGO lubricity, but it was then found that the test had to be modified for fuels of intermediate lubricity. Following the modifications, an extensive round robin was carried out to derive the precision of the method and to examine the correlations between the HFRR results and wear in fuel injection equipment.

The test method, which is available as CEC F-06-A-96, shows a significant precision improvement over previous HFRR procedures, and a strong linear correlation with critical rotary distributor pump wear ratings. A correction factor allows the test to be carried out over a wide range of ambient conditions.