A mass flowmeter is an instrument that determines the flow rate by measuring the mass of the fluid being measured. It is an advanced flowmeter widely used in the field of flow measurement and control of various industrial substances such as air, gas, water, steam, and chemical fluids. The following will introduce the mass flowmeter from the aspects of measurement principle, application characteristics, classification, and type selection.
1. Measurement principle
A mass flowmeter determines the flow rate by measuring the mass of the fluid being measured. Its measurement principle is based on Newton's second law, that is, F=ma (F is the resultant force applied to the object, m is the mass of the object, a is the acceleration applied to the object, and F and a have the same direction). On this basis, a mass flowmeter can calculate the mass of the fluid by measuring the flow rate and density of the fluid within the measurement range, thereby determining the flow rate.
2. Application characteristics
High accuracy: The mass flowmeter uses the gravimetric method to measure fluid mass, without involving the measurement of fluid pressure, temperature, density, and other parameters, so its measurement accuracy can reach 0.1% to 0.5%.
Wide range: Mass flow meters can measure various fluids, including gases, vapors, liquids, and chemicals.
Low resistance: The measurement principle of a mass flowmeter is simple, without mechanical components, and theoretically there is no resistance in the measurement pipeline.
Strong anti-interference ability: The mass flowmeter has certain anti-interference ability against changes in fluid temperature, pressure, density, and other parameters, as well as external interference such as vibration and noise in the pipeline.
Easy maintenance: The mass flowmeter has no moving mechanical components and consumables, and long-term use does not require maintenance and replacement.
3、 Classification and selection
According to the measurement principle, mass flow meters can be divided into four types: thermal type, vibration type, sound velocity type, and nuclide type.
1. Thermal mass flowmeter
Thermal mass flowmeter is a type of instrument that measures mass flow by using the change in resistance of the heating coil resistance and the change in heat that is cooled as it propagates in the fluid. This instrument is suitable for the measurement of liquids, gases, vapors, and other fluids, with a wide measurement range and an accuracy of 0.5%.
2. Vibration mode mass flowmeter
Vibration mode mass flowmeter is used to analyze the characteristics of vibration signals in the measured medium to obtain flow information of the medium. This instrument is mainly suitable for precise measurement of gases and liquids, with high measurement range and resolution, as well as high accuracy.
3. Sound velocity type mass flowmeter
The acoustic velocity type mass flowmeter is a kind of instrument that utilizes the acoustic wave propagated by the fluid in the pipeline to measure the flow rate. This instrument is suitable for liquid and gas flow measurement, and has the advantages of high accuracy, simple operation, and fast response speed.
4. Nuclide type mass flowmeter
The nuclide type mass flowmeter is an instrument that uses radionuclides to radiate a fluid and measure the attenuation of radionuclides in the fluid to measure the flow rate. This instrument is suitable for flow measurement in extreme environments such as high temperature, high pressure, high viscosity, strong corrosivity, and suspended solids.
When purchasing a mass flow meter, it is necessary to select different types and specifications of mass flow meters based on factors such as the physical parameters of the measured medium, measurement conditions, and accuracy requirements.
In summary, mass flowmeter is a reliable, accurate, and easy to operate flow measurement instrument, widely used in the field of flow measurement, control, and monitoring in industrial production, providing an important guarantee for the production process.
