Study on the improvement of acid number determination standard for lubricating oil fraction
This work proposes an improved approach to the GB/T 7304-2014 standard for total acid number determination of lubricating base oils to solve the problems encountered during the determination process.The effectiveness of the improved measures has been veri-fied through a large number of acid value determination experiments.The results indicate that for oil products with low acid concentration,in order to improve the accuracy of acid value measurement and make potential jumps more likely to occur during titration,the qual-ity of the oil sample can be appropriately increased by using a lower concentration of potas-sium hydroxide ethanol titration solution instead of the 0.10 mol/L potassium hydroxide iso-propanol standard solution specified in the standard.At this point,when there is no potential jump in the acid value determination process,pH=12.00 can be considered as the titration endpoint.The research results are expected to serve as a reference for the future revision,further improvement,and development of this standard.