Abstract：In order to establish Chinese micro liquid flow standards, the micro liquid flow facility of different countries and regions have been investigated. The flow range is 50nL/min~1000mL/min, and the uncertainty is 0.04%~4.5%. The parameters such as flow range, uncertainty level, pressure, temperature are collected, and the water supply system, degassing system and liquid collection system of the facility are classified and summarized. The water supply system is mainly composed of capillary tube, injection pump and mass flow controller. The degassing system is mainly composed of ultrasonic degassing or online degassing. The liquid collection system is mainly divided into three methods:the outlet pipe and the beaker form a liquid bridge and humidity trap, the outlet pipe is immersed in the liquid surface and the oil film is covered, and the outlet pipe is immersed in the liquid surface and the humidity trap. Finally, the main sources of uncertainty such as timer drift and communication delay, balance drift and calibration, evaporation, buoyancy and surface tension, flow stability and repeatability are summarized.
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