Advantages and disadvantages of vortex flowmeter
The working principle of vortex flowmeter is to place a non-streamlined vortex generator in the fluid, so that the fluid is alternately separated on both sides of the generator, releasing two series of regularly staggered vortex flowmeter. In a certain range, the vortex separation frequency is proportional to the flow rate, and the vortex flowmeter can measure the flow rate of the medium by calculating the vortex separation frequency.
1. The advantages of vortex flowmeter are:
a. Vortex flowmeter has no moving parts, simple structure, reliable performance and long service life.
b. Vortex flowmeter has a wide measuring range. The range ratio can generally reach 1:10.
c. The volume flow of the vortex flowmeter is not affected by thermal parameters such as temperature, pressure, density or viscosity of the measured flow body. Generally do not need to separate calibration. It can measure the flow of liquid, gas or steam.
d. It causes less pressure loss.
The accuracy is high, the repeatability is 0.5%, and the maintenance is small.
2. Its disadvantages are:
a. The volume flow under the working state of the vortex flowmeter is not affected by thermal parameters such as temperature, pressure and density of the measured flow body, but the measurement result of the liquid or steam should be the mass flow rate, and for the gas, the measurement result should be the standard volume flow rate. The mass flow rate or the standard volume flow rate must be converted by the fluid density, and the change of fluid density caused by the change of fluid condition must be considered.
b. The main factors that cause the flow measurement error are: the measurement error caused by the uneven flow rate of the pipeline; The medium density can not be accurately determined when the fluid condition changes. The wet saturated steam is assumed to be dry saturated steam for measurement. If these errors are not limited or eliminated, the total measurement error of vortex flowmeter will be very large.
c. Poor vibration resistance. The external vibration will cause the vortex flowmeter to produce measurement errors and even not work properly. The impact of high flow rate of channel fluid will cause additional vibration of the cantilever of vortex generator, which will reduce the measurement accuracy. The effect of large pipe diameter is more obvious.
d. Poor adaptability to measuring dirty media. The generating body of vortex flowmeter is easy to be dirty or twisted by dirt, which changes the geometry size and greatly affects the measurement accuracy.
e. High requirements for straight pipe section. The straight pipe section of the vortex flowmeter must be guaranteed for the first 40D and then 20D to meet the measurement requirements.
f. Poor temperature resistance. Vortex flowmeters generally can only measure the fluid flow of the medium below 300 ° C.