Working Principle of Coriolis Mass Flow Meter

The core working principle of the Coriolis Mass Flow Meter (referred to as Coriolis flow meter for short) is to utilize the Coriolis force generated when fluid flows inside a vibrating tube, and directly measure the mass flow rate of the fluid by detecting the phase difference of the vibrating tube. It can also derive and measure parameters such as density and temperature.

Core Principle Breakdown

Generation of Coriolis Force Coriolis force is an inertial force. When an object moves linearly in a rotating reference frame, it is subjected to a force perpendicular to both the direction of motion and the axis of rotation.In a Coriolis flow meter, the vibrating measuring tube acts as the “rotating reference frame”, and the fluid flowing inside the tube serves as the “moving object”.

Vibration Drive of the Measuring TubeThe measuring tube of the flow meter (usually U-shaped, straight, or double-bent) is driven by an actuator at a fixed frequency (natural frequency) to perform periodic reciprocating vibration (similar to the vibration of a tuning fork).When there is no fluid flow inside the tube, the vibration of the measuring tube is symmetrical, and the vibration phases at the inlet and outlet ends of the tube are completely consistent.

Phase Difference Caused by Fluid Flow When fluid flows from the inlet end to the outlet end inside the vibrating tube:

When the fluid vibrates upward with the measuring tube, it is subjected to a Coriolis force that hinders the vibration, resulting in a phase lag at the inlet end of the tube.

When the fluid vibrates downward with the measuring tube, it is subjected to a Coriolis force that promotes the vibration, leading to a phase advance at the outlet end of the tube.

This difference in force causes a phase difference between the inlet and outlet ends of the measuring tube, and the magnitude of the phase difference is directly proportional to the mass flow rate of the fluid.

Signal Detection and Calculation Sensors (such as electromagnetic sensors) are installed at both ends of the measuring tube to detect the vibration phase signals.The transmitter of the flow meter converts the phase difference signal into an electrical signal, and then calculates the mass flow rate of the fluid through a built-in algorithm (direct measurement without the need for temperature and pressure compensation).Meanwhile, the natural frequency of the measuring tube is related to the density of the fluid inside the tube, so the fluid density can also be calculated through the vibration frequency.

Key Features (Combined with Flow Meter Technical Parameters)

Direct measurement of mass flow rate: Unlike volumetric flow meters (such as vortex and electromagnetic flow meters), there is no need for conversion through density, so accuracy and repeatability are less affected by working conditions.

Wide applicability to media: It can measure liquids, gases, and multi phase flows (such as bubble-containing liquids and slurries), and is particularly suitable for high-viscosity, high-temperature, and high-pressure media.

Advantages in technical parameters: The accuracy can usually reach ±0.1%～±0.5%, and the repeatability can reach ±0.02%～±0.1%, complying with international standards such as ISO 9104 and ASTM D5125.