ACCURACY IN EVALUATING IGNITION QUALITY OF DIESEL FUELS IN SINGLE-CYLINDER IT UNITS

A check on the reproducibility of results obtained for the ignition quality of Grade DZ left bracket winter right bracket diesel fuel (GOST 4749-73) in IT9-3 and IDT-69 test units indicates that the true precision of results does not meet the requirements of GOST 3122-67. Results often deviate by more than plus or minus 2 units from the arithmetic average value. It has been demonstrated that the repeatability is unsatisfactory. Moreover, the reproducibility of results between different units is also inadequate. One of the reasons for such deviations can be found in deficiencies of the apparatus for measuring the ignition delay period. This paper presents test results obtained with a newly developed electronic device designated IPZV-1 to measure the ignition delay period for diesel fuels. Data are presented which show that the electronic device for measuring the ignition delay period can not only improve the precision in determining diesel fuel cetane numbers, but also opens up the way to automation of the test procedure.