Seven had more contents about the flowmeter in chemical industry 707 WeChat public platform, this time more than seven friends to seven message, want to see the contents of the flowmeter so today, seven to knowledge sharing with you again flowmeter. Flowmeter is a common measuring instrument. It has high precision, good stability and easy to use. It has a certain application in many fields. There are many kinds of flowmeters, and the functions of each flow meter and the range of measurement are different. Then, how much is the classification of the specific flowmeter? What are the disadvantages and applications of each flowmeter?
Classification of flow meters
Measurement of fluid flow meter and flow meter instrument called. Flowmeter is one of the important instruments in industrial measurement. With the development of industrial production, the accuracy and the range of flow measurement of the increasingly high demand, change rapidly flow measurement technology. In order to adapt to a variety of purposes, the advent of various types of flowmeter. At present, more than 100 kinds of flowmeters have been put into use.
Each product has its specific applicability, but also has its limitations. According to the principle of measurement, there are mechanical principles, thermal principles, acoustic principles, electrical principles, optical principles, principles of atomic physics, and so on.
Classify according to the structure and principle of flowmeter. There are volumetric flowmeter, differential pressure flowmeter, float flowmeter, turbine flowmeter, electromagnetic flowmeter, vortex flowmeter in fluid oscillation flowmeter, mass flowmeter and plug-in flowmeter.
There are two kinds of closed pipelines and open channels according to the object of measurement. They can be divided into total quantity measurement and flow measurement according to the purpose of measurement. Their instruments are called total quantity meter and flowmeter respectively. The total scale measurement of flow through the pipe within a period of time the flow is expressed in a short period of time through the amount divided by the time of the business, in fact usually also have a cumulative flow meter device, make use of the total scale, while the total scale is also available in a traffic signal generating device. Therefore, it has no practical significance to divide the flowmeter and the total meter in the strict sense.
First, according to the principle of measurement classification
1.: mechanical principle belongs to this kind of instrument is using the principle of differential pressure, rotor Bernoulli theorem; using the impulse momentum theorem, the movable tube; using the direct quality type of Newton's second law; the target type principle of fluid momentum; using turbine angular momentum theorem; using vortex, vortex type fluid principle oscillation; use the static pressure difference of pitot tube and volumetric and weir trough, etc..
2. electricity principle: the instrument used in this kind of principle has electromagnetic type, differential capacitance type, inductance type, strain resistance type, etc..
3. acoustic principle: the use of acoustic principles for flow measurement of ultrasonic. Acoustic (shock wave) and so on.
4. principles of heat: the use of thermal principles to measure the flow of heat, direct heat, indirect calorimetry.
5. optical principle: laser, photoelectric and so on, belong to the principle of such instrument.
6., the principle of Physics: nuclear magnetic resonance, nuclear radiation, etc., is a principle of this kind of instrument
7. other principles: labeling principle (tracing principle, nuclear magnetic resonance principle), correlation principle, and so on.
Two, according to the flow structure principle classification
According to the actual situation of the current flowmeter product, according to the structure principle of the flowmeter, it can be generalized into the following types:
1 differential pressure flowmeter
A differential pressure flowmeter is an instrument for calculating flow rates based on the differential pressure produced by a flow measuring device installed in the pipe, the known fluid conditions, and the geometric size of the detector and the pipe.
A differential pressure flowmeter consists of a primary unit (a test piece) and a two unit (a differential pressure converter and a flow indicator). The differential pressure flowmeters are usually classified in the form of test pieces, such as orifice plate flowmeters, Venturi flowmeters, and pitot tube flowmeters.
The two unit is all kinds of mechanical, electronic, electromechanical integral differential pressure meters, differential pressure transmitters and flow meters. It has developed into a series of three types (serialization, generalization and standardization) with high degree of variety and specifications. It can not only measure the flow parameters, but also measure other parameters (such as pressure, physical level, density, etc.).
Differential pressure type flowmeter detection parts according to its function and principle can be divided into: throttling device, hydraulic resistance type, centrifugal type and dynamic pressure head, dynamic pressure and jet type gain categories.
The inspection pieces can be divided into two categories according to their standardization: standard and nonstandard.
The standard test piece is that the flow value and the measurement error can be determined without the real flow calibration as long as the design, manufacture, installation and use of the standard document are carried out.
Nonstandard inspection parts are not mature enough and have not been included in international standards.
Differential pressure type flowmeter is the most widely used in all kinds of flow meters, the amount occupies the first place. In recent years, due to the advent of a variety of new flowmeter, the percentage of its use gradually decreased, but it is still the most important kind of flowmeter.
Advantage:
(1) the most widely used orifice plate type flowmeter has firm structure, stable performance and long service life;
(2) a wide range of applications, so far no class of flow meters can be compared;
(3) inspection parts, transmitters and display instruments are produced by different manufacturers, which is convenient for economies of scale.
Shortcoming:
(1) the measurement accuracy is generally low;
(2) narrow range, generally only 3:1~4:1;
(3) field installation requires high conditions;
(4) pressure loss (finger plate and nozzle etc.).
Application survey:
Differential pressure flowmeter has a wide range of applications. In the flow measurement of closed pipelines, all kinds of objects are applied, such as fluid: single-phase, miscible, clean, dirty and viscous flow
Chinese
English
Current position：
South China