Mass flowmeter is the volume of fluid is a function of fluid temperature and pressure, is a dependent variable, and the quality is not a time of the fluid, temperature, pressure changes in the amount of change, as I mentioned earlier, the commonly used flowmeter, such as orifice meter, laminar flow mass flowmeter, turbine flowmeter, vortex flowmeter, electromagnetic flowmeter, the rotor flowmeter, ultrasonic flowmeter and oval gear flowmeter of the flow measurement value is the volume of fluid flow, in scientific research, production process control, quality management, economic accounting and the trade transfer activities involved in the amount of fluid for quality more commonly, use the meter only measured the volume of fluid flow often cannot meet the requirements of people, still need to try to obtain fluid mass flow rate, usually used in measuring the temperature of the fluid, pressure, density and parameters such as volume, with modification, conversion and compensation methods indirectly get the fluid quality, this kind of measurement method, the intermediate links, mass flow measurement accuracy is difficult to guarantee and improve, with the development of modern science and technology, there appeared some direct measurement of mass flow rate measuring method and device, so as to promote the progress of the flow measurement technology,



According to the measurement principle of classification

Mechanics principle: belong to such a principle of instrument have using Bernoulli's theorem of differential pressure type, rotor type; Using the theorem of momentum impulse type, movable type; Using the Newton's second law directly quality type; Using the fluid momentum principle target type; Using the angular momentum theorem of the turbine; Use principle of fluid oscillation vortex type, vortex type; Using total static pressure difference of pitot tube type and displacement and weir, groove, etc.,

2. Electrical principle: used to such a principle of electromagnetic instrument, the differential capacitive, inductive, strain resistance type, etc.,

3. The principle of acoustics: using acoustic principle of flow measurement with the ultrasonic type. Acoustic type (shock wave type),

4. The optical principle: laser type, such as photoelectric instrument belongs to such a principle,

5. The original in physics, nuclear magnetic resonance (NMR), nuclear radiation type belongs to such a principle of instrument, etc.