尺寸法测量活塞式体积管标准装置标准容积的不确定度评定

Uncertainty Evaluation of the Standard Volume of Piston Pipe Prover Standard Facility by Dimension Measurement

活塞式体积管主要用于石油产品等液体流量的计量,一般通过容积法溯源,受限于上级标准二等金属量器准确度等级。通过容积法测量体积管标准已达技术瓶颈,测量不确定度难以提升。为进一步提高活塞式体积管标准装置的测量准确度,以达到油流量原级标准技术水平,针对该装置自身结构特点,改变惯用溯源方式,提出了尺寸法测量标准容积的方法,即精密测量体积管标准段内径和检测开关间距离,从而计算得到标准容积,将体积量溯源至长度基准,减少溯源环节并提高测量不确定度。建立尺寸法数学模型,分析影响该测量方法不确定度的4个来源,即内径测量、长度测量、线膨胀系数、温度测量,并具体分述和评定了这4个分量,对尺寸法测量活塞式体积管标准装置标准容积进行不确定度的评定。经评定,合成标准装置标准容积相对扩展不确定度为0.010%(k=2),已经达到国际先进水平。

The piston pipe prover is mainly used to measure the flow of petroleum products and other liquids,and is often traced by volumetric method,which is restricted by the accuracy level of superior second-class metal measuring instruments.Measuring pipe prover standards through volumetric methods has reached a technical bottleneck,and the measurement uncertainty is difficult to improve.In order to further improve the measuring accuracy of the piston pipe prover standard facility to reach the original standard technical level of oil flow rate,according to the structural characteristics of the facility,a cali-bration method for measuring the standard volume by dimensional method is proposed by changing the conventional traceability method,that is,the standard volume is calculated by precisely measuring the inner diameter and the distance between the detection switches of the standard section,tracing the vol-ume to the length benchmark,reducing the tracing link and improving the measurement uncertainty.The mathematical model of the dimension method is established,and four sources of uncertainty affect-ing the measurement method are analyzed,namely,inner diameter measurement,length measure-ment,linear expansion coefficient,and temperature measurement.These four components are specifi-cally described and evaluated,and the uncertainty evaluation of the standard volume of piston pipe prover standard facility by dimensional measurement is carried out.After evaluation,the relative expan-sion uncertainty of the standard volume of the standard facility is 0.010%(k=2),which has reached the international advanced level.