Review of different test methods for the evaluation of stability of biodiesel

The vegetable oil, fats and their biodiesel suffer with the drawback of deterioration of its quality when it is in contact with oxygen unlike petroleum diesel. There are various types of stabilities like oxidation, storage and thermal, playing key roles in making the fuel unstable. The present paper is an attempt to review all type of stability measuring test methods to find out the best method for stability measurement. From the review it is found that there are several methods to measure the stability of biodiesel but two test methods emerges the most likely choice for the purpose of measurement of oxidation stability of biodiesel. These are ASTM 2274 and 743 Rancimat test. A comparison between these two shows that these may be used alternatively. Most commonly used methods to investigate the thermal stability are Rancimat test, ASTM D 6408-08, D 5304-06 and TGA/DTA. Rancimat test has been suggested as an important method to measure the thermal stability of oils, fats and biodiesel fuels.