The Coriolis flow meter is basically a mass flow meter. It gives you exactly the mass of CO2 is delivered by the membrane pump, with at least three advantages if compared to traditional meters:
Because of its high pressure, no traditional meters are available for supercritical CO2. Of course this high-performance technology is not cheap. Many systems are not equipped with a flow meter at all, to be more cost-competitive. However, without it you will never be sure if CO2 is truly flowing in the circuit, and exactly how much.
The Coriolis flow meter is essential for proper feedback and control over the CO2 flow in the circuit. The full automation system detects the feedback from the flow meter and drive the motor to give you exactly the expected kg/hr. This is critical, since either lower or higher flow rates provide less-than-optimal extract yields.