蒸发损失测定影响因素研究及不确定度评定

Research on Influencing Factors of Evaporation Loss Measurement and Evaluation of Uncertainty

蒸发损失是表征油品品质的重要指标,我国现行行业标准NB/SH/T 0059-2010《润滑油蒸发损失测定法(诺亚克法)》中的非伍德合金诺亚克B法具有无毒害、能够模拟发动机的实际工况、测试结果准确等优点,在行业中应用广泛。研究了诺亚克B法测量过程中加样量、加热温度、加热时间和真空泵压差等因素对实验结果的影响以及引入的不确定度。研究结果表明,加样量在(65±0.1)g变化时,测试结果变化为±0.019%;加热温度在245.2℃±0.5℃的波动可能引起的测试结果变化不超过±0.27%;每5 s的加热时间变化可能引起测试结果的变化小于0.02%;真空泵压差在(20±0.2)mmH2O压力波动引起的测量结果变化为±0.04%。由加样量、加热温度、加热时长以及真空泵压差引入的不确定度分别为0.011%、0.16%、0.01%和0.02%,各影响因素引入的扩展不确定度为0.32%(k=2)。

Evaporation loss is an important indicator to characterize oil quality. The Noack B method for non-wood alloy in The current industry standard NB/SH/T0059-2010 "Standard test method for evaporation loss of lubricating oils by the Noack method" has the advantages of being non-toxic, able to simulate the actual working conditions of engines and accurate test results, and is widely used in the industry. This paper studied the influence of different factors including sample addition amount, heating temperature, heating time, and pressure difference of vacuum pump on the experimental results and the uncertainties introduced in the process of Noack B method measurement. The research results show that when the sample amount is changed at(65±0.1) g, the test result change is ±0.019%. The fluctuation of the heating temperature at 245.2℃±0.5℃ may cause the test result change not more than ±0.27%. The variation of heating time per 5 s may cause less than 0.02% of the test results. The variation of measurement results caused by the pressure fluctuation of vacuum pump pressure at(20 ± 0.2) mm HO is ±0.04%. The uncertainties introduced by the sample addition amount, heating temperature,heating time, and vacuum pump pressure difference are 0.011%, 0.16%, 0.01%, and 0.02%, respectively, and the expanded uncertainty introduced by each influencing factor is 0.32%(k=2).