English: Illustration for the mass flow meter operating principle.

This is the fourth animation of a group of four.
The previous animation is Image:Coriolis_meter_vibrating_no-flow_512x512.gif. Fluid is being pumped through the mass flow meter. When there is mass flow, the tube twists slightly. The arm through which fluid flows away from the axis of rotation must exert a force on the fluid to increase its angular momentum, so it is lagging behind the overall vibration. The arm though which fluid is pushed back to the axis of rotation must exert a force on the fluid to decrease the fluid's angular momentum again, hence that arm is pulling ahead of the overall vibration. The inlet arm and the outlet arm vibrate with the same frequency as the overall vibration, but when there is mass flow, the two vibrations are out of sync. The two vibrations are shifted in phase with respect to each other, and the degree of phase-shift is a measure for the amount of mass that is flowing through the tubes.

A flow meter that uses the Coriolis effect for its operating principle is also called a Coriolis flow meter.