电力用油酸值测定标准修正

Modification of acid value measuring standard for oil used in electric power industry

GB/T 264-1983《石油产品酸值测定法》和GB/T 28552-2012《变压器油、汽轮机油、抗燃油酸值测定法(BTB法)》测定电力用油酸值时,再现性较差。分析原因为当油样的酸值较大时,在上述2种标准方法指示剂的变色区域内,溶液pH值随碱液的体积变化不明显,不出现滴定突跃,溶液的颜色也不能发生突变,导致无法准确判断滴定终点。对此,建议将滴定终点修正为:用碱兰6B作指示剂时,溶液的蓝色消失;用BTB作指示剂时,溶液由黄色变为黄绿色;对于颜色较深,终点难以判断的油样,减少称样量。方法经修正后,有效改善了再现性差的问题,有利于电力用油质量监督。

The reason for poor reproducibility of the results obtained by two test methods for elec tric oil acid value detection,GB/T 264--1983 （Petroleum products--Determination of acid num ber） and GB/T 28552 2012 （Determination of acid number in transformer and turbine oils in service by B TB method （BTB method））, was analyzed. It finds out that, when the acid value of the oil is relatively high, within the color changing range of the indicator in above two standards, the pH value of the solution varied little with the alkali liquor volume, and no titration jump oc curred, so the solution＇s color had no sudden change,resulting in difficult in judging the titration end-point. It suggests that, when using alkali bule 6B as the indicator, the titration end-point be the point when blue color disappears;when using BTB as the indicator,the titration end-point be the point when yellow changes for yellowish-green;for the oil with heavy color which is difficult to determine the titration end-point, the sample weight should be reduced. After the above modifi- cations, the poor reproducibility of the results has been greatly improved, which is beneficial to the electric oil quality supervision.