Coriolis flow measurement is a highly accurate method used to measure the flow rate of liquids and gases in various industrial processes. It operates based on the principle of Coriolis force, which is the apparent deflection of moving objects caused by the rotation of the Earth. Here's how Coriolis flow measurement works:

1. Principle of Operation:

   • Coriolis flow meters consist of a flow tube through which the fluid passes. This flow tube is typically made of metal and is often shaped into a curved or serpentine path.
   • As the fluid flows through the flow tube, it is subjected to periodic vibrations generated by one or more drive coils mounted on the tube.
   • These vibrations cause the flow tube to oscillate in a twisting or bending motion, creating a Coriolis force that acts perpendicular to the direction of fluid flow and the direction of tube vibration.
   • The Coriolis force causes the flow tube to deform slightly, resulting in a phase shift or time delay between the inlet and outlet sections of the tube.
   • By measuring this phase shift or time delay, the flow meter can determine the mass flow rate of the fluid passing through the tube.

2. Measurement Technique:

   • Coriolis flow meters typically use one of two main measurement techniques: the "vibrating tube" or "dual-tube" method.
   • Vibrating Tube Method: In this method, a single flow tube is subjected to periodic vibrations, and the resulting phase shift or time delay is measured to determine the mass flow rate.
   • Dual-Tube Method: In this method, two parallel flow tubes are vibrated simultaneously, and the phase shift or time delay between the tubes is measured. This method provides redundancy and improved accuracy compared to the vibrating tube method.

3. Measurement Output:

   • Coriolis flow meters provide direct measurement of mass flow rate, which is independent of fluid properties such as density, viscosity, temperature, and pressure.
   • Some Coriolis flow meters also provide additional outputs, such as volumetric flow rate, density, temperature, and totalized flow volume.

4. Advantages:

   • High Accuracy: Coriolis flow meters offer high accuracy and repeatability, typically within ±0.1-0.5% of the actual flow rate.
   • Direct Mass Flow Measurement: Coriolis flow meters directly measure mass flow rate, making them suitable for applications where accurate mass measurement is critical.
   • Wide Rangeability: Coriolis flow meters have a wide turndown ratio and can accurately measure flow rates over a broad range of flow velocities.
   • No Moving Parts in Flow Stream: Coriolis flow meters have no moving parts in the flow stream, resulting in minimal pressure drop and reduced risk of wear or clogging.

5. Applications:

   • Coriolis flow meters are used in various industries and applications, including:
     • Oil and gas production and refining.
     • Chemical processing.
     • Food and beverage processing.
     • Pharmaceutical manufacturing.
     • Water and wastewater treatment.
     • HVAC (Heating, Ventilation, and Air Conditioning) systems.
     • Custody transfer and fiscal metering.

Coriolis flow measurement offers numerous advantages in terms of accuracy, reliability, and versatility, making it suitable for a wide range of industrial applications. However, they may have limitations in certain extreme conditions, such as high temperatures, high pressures, or abrasive fluids. Proper installation, calibration, and maintenance are essential to ensure optimal performance of Coriolis flow meters.