Principles and features of Coriolis flow meters
Various types of flow meters and flow sensors are available. This section summarizes the principles and features of Coriolis flow meters.
Coriolis flow meters are flow meters that use a physical phenomenon called the Coriolis effect inside the flow meter itself. As seen in the illustration below, when fluid flows through a vibrating U-shaped pipe, the Coriolis effect goes into action, reversing the flow between the entrance-side, A, and the exit-side, B, and twisting the pipe. With the Coriolis effect, the weight and speed of an object are proportional to each other, so the amount of twist is measured and mass flow is understood.
・Can measure mass flow
・A section of straight pipe is not required
・Able to detect high-viscosity liquids
・Can measure density
|CONS||・High-priced compared to other detection principles
・Pressure loss is large
・Easily affected by vibration
In the northern hemisphere, a bullet that is shot directly north from the equator will veer slightly east (right) of the target. This is because the earth rotates from west to east and the moving speed of an object from a resting state at the equator is fast, so the effect of inertia goes into action at the target point.
In a similar manner, if the amplitude at the midpoint of the U-shaped tubes is increased to create large vibrations, once fluid flows through the inside of the tubes, a Coriolis effect in which the mass and speed of the flow (mass flow) is proportional to each other, goes into action.
The effect works in opposite directions for the entrance and exit sides, twisting the pipes. By comparing the pipe entrance and exit side output voltage signals, performing a calculation, and then measuring the amount of twist, mass flow is understood.
FLOW METER TYPES & PRINCIPLES
SOURCES OF TROUBLE FOR FLOW METERS