差值法测定乳化油中水分的应用研究

Application of differential techniques in the measurement of moisture in emulsified oil

润滑油是轨道交通车辆正常运行的重要保障,而水分是润滑油的重要指标。齿轮箱进水导致润滑油乳化是常见故障,用卡尔费休法测定某些润滑油的水分有干扰,无法准确测定其水分。文章阐述了卡尔费休法的原理和干扰产生的原因,以及乳化油中乳滴形状和受力情况,研究了水分为1 000~10 000 mg/kg的乳化油在100~140℃加热0~35 min水分变化的情况,分析了游离水、悬浮水、溶解水在升温、蒸发、扩散阶段水分蒸发情况及影响因素。综合试验数据和理论分析,得出结论:将乳化油在120℃下加热15 min,利用差值法消除干扰,可以准确测定乳化油中的水分。此方法使用常规仪器,操作简单,结果准确,具有良好的精密度和准确度。

Lubricating oil is an important guarantee for smooth operation of rail transit vehicles,and moisture is an important indicator of lubricating oil.The emulsification of lubricating oil resulting from water ingress into the gearbox is a common fault.As Karl Fischer method interferes with the determination of the moisture content of certain lubricating oils,it's difficult to accurately determine their moisture content.This paper explains the principle of Karl Fischer method and the causes of the interference,as well as the shape and stress of the emulsion droplet in emulsified oil,studies the changes in moisture content of emulsified oil with a water content of 1000-10000 mg/kg when heated at 100-140℃for 0-35 minutes,and also analyzes the water evaporation situation and influence factors of free water,suspended water,and dissolved water in heating,evaporation,and diffusion stages.Based on test data and theoretical analysis,it is concluded that heating the emulsified oil at 120℃for 15 minutes and using the differential method to eliminate interference can accurately determine the moisture content in the emulsified oil.This method uses commonly easy-to-operate instrument and can obtain excellent accuracy.