Micro flow metrology

Purpose and goal

The need to measure low flow rates with low uncertainty is increasing, especially in the pharmaceutical industry. This project deepend the skills in the National Metrology Laboratory and develop resources to provide traceability in the micro flow area. The goal was to develop a gravimetric primary microfluidic standard in flow rate range between 0.1 ml/min to 10 ml/min for ultra pure water at ambient pressure and temperature with U (k = 2) 0.5%. The goal was fulfilled.

Results and expected effects

New developments in nanotechnology, is increasing the need to measure small quantities of liquids, especially in the order of micro-liters / min down to nano-liters / min. The need for this type of traceable measurements come mainly from the fields of health which, among other things, deals with very high demands on controlled dosing / injection of certain types of medications, but also from biotechnology, vacuum metrology as well as in the automotive industry. HPLC (High Performance Liquid Chromatography) is another application requiring control of very small flows.

Approach and implementation

This one-year project contained following activities: 1. Construction of a flow rig based on three main methods for measuring micro flow at ambient pressure and temperature. 2. Investigations of influence factors such as thermal effects, volume, water absorption, leakage, pulsatile flow, capillary, buoyancy and impact effects, pollution, air bubbles and environmental effects. 3. Improvements to the flow rig to achieve the goal of an expanded measurement uncertainty of U (k = 2) 0.5% 4. Presentation and publication of the project results.