A vortex flow meter is a volumetric flow meter that measures the volumetric flow rate of gases, steam, or liquids under standard conditions, or the mass flow rate of gases, steam, or liquids, based on the Karman vortex street principle. When fluid flows through the vortex flow meter's collecting rod, vortices are formed. The frequency of vortex shedding is proportional to the fluid velocity, and temperature and pressure compensation can be configured.
Advantages and disadvantages of vortex flow meters
A vortex flow meter is a new type of flow meter developed based on the Karman vortex street principle, possessing internationally advanced technology. It is mainly used for measuring the flow rate of fluids in industrial pipelines, such as gases, liquids, and steam.
Advantages of vortex flow meters
1. Low pressure loss, approximately 1/4 to 1/2 that of a throttling differential pressure flow meter.
2. Outputs a pulse signal proportional to the flow rate, with no zero drift.
3. Simple and robust structure, easy to install and maintain. No need for pressure guide pipes, three-valve manifolds, etc., reducing leakage, blockage, and freezing. This measuring element has a simple structure, reliable performance, and long service life.
4. High accuracy, typically ±(1～1.5)%R.
5. Wide measurement range; for vortex flow meters with a suitable diameter, the range can reach 20:1.
6. Within a certain Reynolds number range, the output frequency of the orifice flow meter is unaffected by the fluid's physical properties (density, viscosity) and composition; that is, the instrument coefficient is only related to the shape and size of the vortex generator and the pipe.
7. The volumetric flow rate of the vortex flow meter is unaffected by the thermal parameters of the measured fluid, such as temperature, pressure, density, or viscosity. Typically, no separate calibration is required. It can measure the flow rate of liquids, gases, or steam.
1. The volumetric flow rate of a vortex flow meter is unaffected by the thermal parameters of the measured fluid, such as temperature, pressure, and density. However, for liquids or steam, the final measurement result should be the mass flow rate. For gases, the final measurement result should be the standard volumetric flow rate. Both mass flow rate and standard volumetric flow rate must be converted using fluid density, and changes in fluid density due to variations in fluid conditions must be considered.
2. The main factors causing flow measurement errors include: measurement errors caused by uneven flow velocity in the pipeline; inability to accurately determine the medium density when fluid conditions change; and assuming wet saturated steam is dry saturated steam for measurement. If these errors are not limited or eliminated, the total measurement error of the vortex flow meter will be very large.
3. Poor vibration resistance. External vibrations can cause measurement errors in vortex flow meters, or even prevent them from functioning properly. High-speed impacts of the fluid in the channel can generate additional vibrations on the cantilever of the vortex generator, thus reducing measurement accuracy. The effect is more pronounced with larger pipe diameters.
4. Poor adaptability to dirty media. The generator of a vortex flow meter is easily contaminated by the medium or entangled in dirt. Changes in its geometric dimensions have a significant impact on measurement accuracy. 5. High requirements for straight pipe sections. Experts point out that the straight pipe sections of a vortex flowmeter must ensure that the upstream 40D and 20D meet the measurement requirements.
6. Poor temperature resistance. Vortex flowmeters can generally only measure the flow rate of fluids below 300℃.
Vortex flowmeters are suitable for flow measurement of most liquids and gases, especially in high-temperature, high-pressure, or corrosive media. They are widely used in flow measurement in petrochemical, power, steel, chemical, and water conservancy industries.
Vortex flowmeters can measure the flow rate of various media, including liquids and gases. Common liquid media include water, petroleum, and acid/alkali solutions; common gaseous media include natural gas, coal gas, and air. Vortex flowmeters are suitable for flow measurement in industrial production and can measure over a wide range of temperatures, pressures, and viscosities, featuring high accuracy, good linearity, and high stability.