Marvin Robert S
Institute for Basic Standards, National Bureau of Standards, Washington, D.C. 20234.
J Res Natl Bur Stand A Phys Chem. 1971 Nov-Dec;75A(6):535-540. doi: 10.6028/jres.075A.041.
Most absolute measurements of viscosity have utilized capillary flow, and required semiempirical corrections amounting to several times their precision and estimated accuracy. The range of values found from these measurements and the possibility of unrecognized systematic errors make it impossible to base a realistic estimate of accuracy on the results of only one type of measurement. The results of two independent absolute measurements involving different types of flow, reported in the two accompanying papers, are summarized here. The estimated accuracy in each case is about 0.1 percent. The two results differ by 0.5 percent. It is suggested that we continue to base the calibration of relative viscometers on the value of 1.002 centipoise (cP) for the viscosity of water at 20 °C and one atmosphere. This provides a generally accepted base which limits comparability only by the precision of the measurements. However, whenever the true values of viscosity are required the limits of uncertainty including an estimate of systematic error should be taken as no better than ±0.25 percent.
大多数粘度的绝对测量都采用了毛细管流动法，并且需要进行半经验校正，校正值相当于其精度和估计准确度的几倍。从这些测量中得到的值的范围以及未被识别的系统误差的可能性使得仅基于一种测量结果进行现实的准确度估计变得不可能。在两篇随附论文中报告的涉及不同类型流动的两项独立绝对测量结果在此进行总结。每种情况下的估计准确度约为0.1%。这两个结果相差0.5%。建议我们继续将20℃和一个大气压下水的粘度值1.002厘泊（cP）作为相对粘度计校准的基础。这提供了一个普遍接受的基础，仅通过测量精度来限制可比性。然而，每当需要粘度的真实值时，包括系统误差估计在内的不确定度极限应不超过±0.25%。
