A Critical Appraisal of the Ignition Delay Meter Used in Standard Diesel Fuel Cetane Tests

This paper presents the results of an experimental investigation with five fuels (distillates, catalytically cracked, and vegetable oil blends - Cetane ratings from 20 to 70), which assessed:

• the accuracy of the ignition delay value displayed by the ignition delay meter specified by the ASTM D-613 Cetane rating method;
• the extent to which the accuracy of the meter is dependent on fuel type;
• the effect on Cetane Number value of errors in ignition delay introduced by the meter;
• ways in which the meter accuracy could be improved.

The paper concludes that the major error in ignition delay displayed by the meter is fuel dependent, and can be ascribed to a particular part of the meter circuit. A way in which this weakness could be eliminated is described.