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You have probably seen the principle of a Coriolis mass flow meter at work in your yard.
When you turn the water on quickly, the hose will "kick", when you turn the water on slowly the hose will only move slightly. The amount of movement is related to the weight of water that passes in a given time. By measuring the amount of movement, you can tell how many pounds or kilograms are passing.
A tube that is shaking, and has more mass passing through it, will shake further. If you pass less weight through it the shaking movement will be less. Long things have a lower natural frequency than short things. So a long loop tube meter shakes at a lower natural frequency than a meter that has short tubes in it.
We are therefor considering items, which are vibrating at their own natural frequency.
We are interested in how far they swing or vibrate.
Unfortunately, if the piping system to which they are fitted, happens to have some other component with the same, or multiple of the natural frequency of the meter, then resonance may cause the meter to become over excited, swing more wildly, and read a greater mass flow than is actually passing through it. Check valves, flow controls that modulate, relief valves, impellers, vanes, gear teeth, even nodes of pipe length; any or all of them can cause the acoustic frequency response of your system to prevent your mass meter from reading correctly.
The amplitude of pressure pulsation is generally not detrimental to this type of mass meter, the frequency is. If you experience meter inaccuracy, it is wise to quite the system down so that there is less than a 1% amplitude at any frequency, this way there will not be enough excitation force, to stop the meter from working as designed.
UNDERSTANDING FLOW OR PRESSURE PULSATION
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