Principle analysis of various types of flowmeters
(1) Principles of mechanics: Instruments belonging to such principles have differential pressure and rotor type using Bernoulli's theorem; impulse type and movable tube type using momentum theorem; direct mass type using Newton's second law; The target type of the momentum principle; the turbine type using the angular momentum theorem; the vortex type using the principle of fluid oscillation, the vortex type; the pitot tube type using the total static pressure difference; the volumetric type, the enthalpy, the trough type, and the like.
(2) Electrical principle: The instruments used for such principles are electromagnetic, differential capacitive, inductive, strain resistant, etc.
(3) Acoustic principle: Ultrasonic type, acoustic type (shock wave type), etc. are used for flow measurement using the acoustic principle.
(4) Thermal principle: The heat, direct thermal, indirect calorimetry, etc., which measure the flow using the thermal principle.
(5) Optical principle: laser type, photoelectric type, etc. are instruments belonging to such principles.
(6) Originally based on physical principles: nuclear magnetic resonance, nuclear radiation, etc. are instruments of this type.
(7) Other principles: Marking principle (trace principle, NMR principle), related principles, etc.
Liquid turbine flow meter classification and function description
Keywords: liquid turbine flowmeter, diesel liquid turbine flowmeter, pure water liquid turbine flowmeter
First, the liquid turbine flowmeter overview
The liquid turbine flowmeter is the main type of impeller flow (flow rate) meter, and the impeller type flowmeter also has an anemometer and a water meter. The TUF consists of a sensor and a conversion display. The sensor uses a multi-blade rotor to sense the average flow rate of the fluid, thereby deriving the flow or total amount. The rotational speed (or number of revolutions) of the rotor can be detected mechanically, magnetically, and photoelectrically and displayed and transmitted by the reading device.
Second, liquid turbine flowmeter classification
According to the classification of instrument functions, SDLWGY series turbine flowmeters can be divided into 2 categories.
1, turbine flow sensor / transmitter
2, intelligent integrated turbine flowmeter
Third, the liquid turbine flowmeter function description
1, turbine flow sensor / transmitter
This type of turbine flow product itself does not have a live display function, only the flow signal is transmitted far. The flow signal can be divided into pulse signal or current signal (4-20mA); the instrument is low in price, high in integration and small in size, and is especially suitable for use with computer control systems such as secondary display, PLC, DCS.
First, the gas turbine flowmeter installation requirements
1. When the gas flowmeter is installed, it is strictly forbidden to directly conduct electric welding at the inlet and outlet flanges to avoid burning the internal parts of the flowmeter;
2. For the newly installed or overhauled pipeline, it must be purged to remove the debris in the pipeline before installing the flowmeter;
3. The gas turbine flowmeter should be installed in a place that is easy to maintain, has no strong electromagnetic field interference, no mechanical vibration and thermal radiation;
4. Gas turbine flowmeters should not be used in places where flow is frequently interrupted and there is strong pulsating flow or pressure pulsation;
5, the gas turbine flowmeter should ensure that the pipeline is coaxial, and prevent the gasket from protruding into the pipeline, otherwise it will disturb the flow profile;
6. The flow direction of the gas turbine flowmeter should be consistent with the direction marked on the casing. The upper and lower pipelines of the flowmeter should be guaranteed with 2DN and 1DN straight pipe sections;
7. When using external power supply, the flowmeter must have reliable grounding, but it should not share the grounding wire with the high-power system; when the pipeline is installed or repaired, the grounding wire of the welding system should not be overlapped with the flowmeter.
8. Since the flowmeter needs to be repaired and calibrated, in order to ensure normal gas supply, bypass piping should be set. The bypass pipe valve must be closed during normal use;
9. When constructing pipelines, it is advisable to install telescopic tubes or bellows to avoid serious stretching and causing breakage of the flowmeter;
10. When the gas turbine flowmeter is installed outdoors, the upper part should be covered to prevent the rainwater from immersing and the sun exposure affecting the service life of the flowmeter;
11. When installing the gas turbine flowmeter, it is advisable to add a filter to the flowmeter (filtering accuracy is recommended ≤20μm).
Second, gas turbine flowmeter requirements
1. When the gas turbine flowmeter is put into operation, the upstream valve of the flowmeter should be slowly opened (not less than 15 seconds), and then the downstream valve of the flowmeter should be slowly opened to prevent the instantaneous airflow from rushing to the turbine;
2. When the flowmeter needs to have a long-distance signal, it should be connected to the external power supply (+12~+24VDC) strictly according to the electrical performance index of the gas turbine flowmeter. It is strictly forbidden to directly connect 220VAC (or 380VAC) power supply at the signal output.