Objective: To investigate the criteria for evaluating shear stress measuring range and the lowest measurable shear stress of rotational viscometer. Methods: We proposed double 5% criteria for the evaluation,I.e. Less than 5% error in viscome-try and less than 5% in coefficient of variation as "measurable" criteria. We used an anonymous viscometer, several kinds of strandard oils, and distilled water as a low viscosity Newtonian fluid. Their viscocities were measured at programmed down-hill shear-rates of 200 s-1, 180 s-1,10 s-1, 5 s-1, 3 s-1 and 1 s-1. SPSS15.0 was used for statistical analysis. Results: We estimated that the maximum measurable shear-stress should beyond be 4000 mPa, and the lowest measurable shear-stress should be a value between 6.92 mpa~9.0 mPa (7 mpa~9 mPa roughly), agreeable with the discription in the specification. Conclusions: The double 5% criteria for evaluating shear-stress measuring range and the lowest measurable shear-stress of a rotational viscometer are meaningful and practical.%目的:判定评估旋转粘度计测量剪应力的范围及最低可测剪应力的标准.方法:我们提出了双5％的方法作为“衡量”标准,即粘度测定误差小于5％、变异系数小于5％.我们采用一种匿名的粘度计、几种不同的粘度油,并把蒸馏水作为低粘度牛顿流体,在切变率分别为200 s-1、180 s-1、10 s-1、5 s-1、3 s-1和1s-1的情况下测量标准油的粘度.我们采用SPSS15.0进行数据的统计学分析.结果:我们估算出该设备的最大可测量的剪应力超出4000 mPa,最小剪应力应该是一个在6.92 mpa ～9.01 mPa(大致上是7mpa～9 mPa)之间的值,与该仪器说明书中的描述相符.结论:用“双5％”的标准评估旋转粘度计的剪应力测量范围和最小剪应力值是有实践意义的.采用此标准,并选定合适的标准油,可以很容易地实现对旋转粘度计的关键性能的评估.
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