Design considerations and initial validation of a liquid microflow calibration setup using parallel operated syringe pumps

Danish Technological Institute (DTI) currently offers traceable calibration of liquid flow rates down to 5 L h−1. However, the industry also requests traceable calibration below this point for flowmeters and pumps. Therefore, DTI is in the process of establishing a traceable calibration setup for such microfluidic devices. This paper addresses the design and uncertainty considerations for a setup based on gravimetric and volume traceability. The flow generation in the setup utilizes two parallel operated syringe pumps with different syringe volumes. The two syringes are programmed so one syringe can replace the pumping action of the second syringe without influencing the resulting flow. In that way it is possible to generate flow rates for calibration in the range from 6 L h−1 to 20 µL h−1. Traceability is currently achieved gravimetrically using special-purpose toploader balances. The resulting expanded uncertainty is expected to be below 0.1% between 6 L h−1 and 100 mL h−1, gradually increasing towards 2% between 100 mL h−1 and 1.2 mL h−1. Furthermore, a concept is proposed to achieve traceability in the full flow range from 6 L h−1 to 20 µL h−1 based on delivered volume divided by time with glass syringes as reference and an expanded uncertainty expected to be below 2%.
Keyword: Uncertainty,Microfluidics,Microflow,Volume,Traceability,Calibration,Gravimetric,Syringe pump