Coriolis mass flow measuring principle

The operating principle of a Coriolis flow meter is basic but very effective. This phenomenon is all around us in the physical world; for example the earth’s rotation and its effect on the weather.

A Coriolis flow meter contains a tube which is energized by a fixed vibration. When a fluid (gas or liquid) passes through this tube the mass flow momentum will cause a change in the tube vibration, the tube will twist resulting in a phase shift. This phase shift can be measured and a linear output derived proportional to flow.

As this principle measures mass flow independent of what is within the tube, it can be directly applied to any fluid flowing through it - LIQUID or GAS - whereas thermal mass flow meters are dependent of the physical properties of the fluid.

Furthermore, in parallel with the phase shift in frequency between inlet and outlet, it is also possible to measure the actual change in natural frequency.

This change in frequency is in direct proportion to the density of the fluid – and a further signal output can be derived. Having measured both the mass flow rate and the density it is possible to derive the volume flow rate.


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