一、计量系统的准确度等级组成天然气计量系统的流量计和二次仪表的准确度至少应满足国家法规或合同要求,计量系统准确度及配套仪表准确度应符合表1和表2的规定。二、评定计量系统不确定度的方法用于贸易交接的流量计属于强制检定计量器具,目前我公司超声波流量计大多在国家石油天然气大流量站南京分站进行实流检定,故 First, the accuracy of the measurement system The composition of natural gas measurement system flowmeter and secondary instrument accuracy should meet at least the national laws and regulations or contract requirements, measurement system accuracy and supporting the accuracy of the instrument should comply with the provisions of Table 1 and Table 2. Second, the method of assessing the uncertainty of the measurement system The flow meter used for the transfer of trade is compulsory testing of measuring instruments, the majority of our ultrasonic flowmeter at the National Oil and Gas large flow station in Nanjing sub-station real-time test, so