Working principle of mass flowmeter and how to choose suitable mass flowmeter
In daily life, we hear more about the turbine flowmeter, electromagnetic flowmeter and so on, but for the mass flowmeter, how much do you know? Now let's talk about the working principle of mass flowmeter and how to choose the right mass flowmete
Mass flowmeter uses Coriolis principle, that is, the phase difference of vibration frequency of the lower part of the measuring tube is proportional to the mass flow rate to measure the flow rate, and the density is obtained by the functional relationship between the resonant frequency of the measuring tube and the density of the measured medium in the tube. From the two basic parameters of mass flow qm and density ρ derived volume flow qv(=qm/e), if the measured liquid is two kinds of density difference phase soluble or insoluble mixed liquid, the density calculation of a liquid in the concentration of mixed liquid, such as oil nail oil water mixture water content, in the measurement of liquid solid two-phase flow can be measured solid content.
It is known from the principle that the mass flowmeter in the flow measurement industry is generally able to directly measure the mass flow of the fluid medium without compensation by other parameters. Its most remarkable feature is that it can directly measure the mass flow rate of the medium, and is not affected by the pressure, temperature and other factors of the working state of the medium.
Mass flowmeter is a kind of novel instrument to measure the mass flow of fluid directly and precisely. Its mass flowmeter is classified as follows:
① direct mass flowmeter
That is, the quantity proportional to the mass flow rate is directly detected, and the detection element directly reflects the mass flow rate.
② Derived mass flowmeter
Mass flow rate is measured by volume flowmeter and densimeter, volume flow rate and fluid density are detected at the same time, and the output signal related to mass flow rate is obtained through calculation.
③ Compensated mass flowmeter
At the same time, the volume flow of the fluid and the temperature and pressure of the fluid are detected. Then, according to the relationship between the fluid density and temperature and pressure, the density value of the fluid under this condition is calculated by the calculation unit, and the mass flow value of the fluid is calculated.
Now there are many kinds of flowmeters in the market, the price is different, there are many domestic and foreign brands, it is easy to cross the eyes. So how do we choose the right mass flowmeter?
1, fluid type: for clear and mixed liquid, clean gas and mixed gas need to choose different flowmeters. For example, turbine flowmeter is generally suitable for liquid, and electromagnetic flowmeter is more suitable for gas. Of course, this is only the choice of most people, but not certain. You can choose according to specific needs.
2, flow range: fluid flow range should be moderate, can not exceed the range of the flow meter.
3, pipe size: for smaller pipe size, generally choose rotor, turbine and mass flowmeter, for large pipe diameter generally use electromagnetic flowmeter and ultrasonic flowmeter. Some materials of pipe are not suitable for electromagnetic and ultrasonic.
4, signal output: but do not require a signal output, generally use the rotor flowmeter and mechanical water meter can be. Output signals are analog (4-20 mA, 0-10 v) and pulse output, and these flowmeters can have digital displays.