Flow meter, what is and how use it?

Hi folks. There been a while I didn't wrote something about basic principle. And for this session, I would like to write about Flow Meter. Flow meter is the quantification of bulk and fluid movements . Flow are generally measured in many different ways. Positive-displacement flow meters accumulate a set volume of fluid and then count the number of times the volume is filled to measure flow. Other flow measurement methods depend on forces produced by the flowing stream as it overcomes a known constriction, to indirectly calculate flow. Flow may be measured by measuring the velocity of fluid over a known area.