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.
Third, the spiral vortex flowmeter measurement characteristics
The spiral vortex flowmeter is a flowmeter that began to appear in the 1970s. Its working principle is: the gas that enters the gas swirling vortex flowmeter is first forced by the spiral spinner to accelerate the rotation to form a vortex, the center of the vortex. For the vortex core. The accelerated vortex enters the enlarged section and then decelerates sharply. The pressure rises to produce a recirculation. Under the action of the recirculation, the vortex core makes a spiral precession around the axis of the flowmeter. The flow rate Q can be derived by measuring the vortex precession frequency f by sensing the sensitive component.
Fourth, gas turbine flowmeter and spiral vortex flowmeter measurement difference
The gas turbine flowmeter has a small pressure loss and can be suitable for gas metering in low pressure conveying applications. Gas-injected vortex flowmeters have a slightly higher pressure loss, and gas metering in low-pressure delivery situations sometimes has problems.
Gas turbine flowmeters require high media cleanliness and can be damaged if used improperly. The gas swirling vortex flowmeter gas swirling vortex flowmeter requires no gas turbine flowmeter and is not damaged.
Gas turbine flowmeters are highly accurate. It is the most accurate of all flow meters. The gas spiraling vortex flowmeter is not as accurate as the former.
Maintenance of the turbine flowmeter sensor section:
1. Before the sensor is installed, use the mouth to blow or hand the impeller to make it rotate quickly to see if there is any display. Install the sensor when there is display. If there is no display, check the relevant parts and troubleshoot.
2. When using, keep the measured medium clean and free of impurities such as fibers and particles.
3. When the turbine flow sensor starts to use, the sensor should be slowly filled with the medium, and then the outlet valve should be opened (the valve should be installed at the back end of the flowmeter). It is forbidden to be impacted by the high-speed fluid when the sensor is in the mediumless state.
4. The maintenance period of the turbine flow sensor is generally half a year. When cleaning and cleaning, please be careful not to damage the parts in the measuring chamber, especially the impeller. Please be optimistic about the positional relationship between the guide and the impeller during assembly.
5. When the turbine flow sensor is not in use, the internal medium should be cleaned, and after drying, a protective cover is added at both ends of the sensor to prevent dust from entering, and then stored in a dry place.
6. The filter used in the turbine flowmeter should be cleaned regularly. When not in use, the internal medium should be cleaned. As with the sensor, add a dust jacket and store it in a dry place.