RDSZ-303J acid value tester is a fully automatic instrument which uses extraction method to accurately detect the value of insulating oleic acid. The Insulating Oil Acid Value Tester instrument improves the working efficiency and test accuracy, reduces the operator's contact with samples and reagents, and ensures the personal safety to the maximum extent. The instrument is equipped with standard acid and calibration program for calibrating the instrument. The user can calibrate the instrument and Neutralization Solution at any time, which overcomes the defect that the concentration of neutralization solution changes in use. At the same time, the transformer oil acidity analysis instrument automatically deducts the background value of extraction solution in the determination, which overcomes the influence of the background value changes in the use of extraction solution on the results. So that the test results are more accurate and reliable.