Establishment of Micro Liquid Flow facility at NIM

Tao Meng, Chang Zhou, Li Liu, Huichao Shi, Dongjun Li, Bo Wu
In order to meet the needs of micro-flow measurement in industrial, biological and medical fields, the National Institute of Metrology (NIM) has established a micro liquid flow facility based on dynamic weighing method, with the flow rate range of 100 nL/min ~ 150 mL/min. The facility is composed of two sets of high accuracy electronic balances as the main standard, and three Coriolis mass flowmeters and two sets of independentpipeline systems according to different flow rate ranges. It has been designed a special degassing, a filter and a pipe air exhausting system, as well as a group of weighing containers and syringes of different specifications. An acquisition method of weighing value based on the fluctuation frequency is adopted to effectively reduce the uncertainty introduced by dynamic reading. A ‘dual time’ method is used to realize the synchronization between weighing system and meter under test by the "time stamp" with resolution of 1 ms. The uncertainty sources of balance that came from weighing accuracy of mg magnitude, short-term drift and long-term stability are evaluated by experimental method. In addition, the uncertainty introduced by liquid evaporation and capacity change of middle pipe are also analyzed. The results show that the facility uncertainty is better than 1.5 % (k = 2) at 100 nL/min flow rate, and the uncertainty is better than 0.1 % (k = 2) when the flow rate is above 1 mL/min.
Liquid flow; Micro flow; Dynamic gravimetric method; Uncertainty budget
Event details
Event name:

19th International Flow Measurement Conference 2022

Chongqing, CHINA
01 November 2022 - 04 November 2022