The working principle of the intelligent vortex flowmeter is to set vortex generators in the fluid, and alternately generate regular vortexes on both sides of the generator. The vortex arrays are arranged asymmetrically downstream of the vortex generators. The so-called Karman vortex street "Vortex Street will produce a certain frequency, through the formula f = St * v / (1-1.27d / D) * d, (St is the Strouhal number, is the dimensionless number, and the vortex generator and Renault The number is related; v is the flow velocity; d is the width of the oncoming face; D is the nominal diameter) and the flow velocity can be obtained. 43 Tv Case,Generoustelevision Case,Flat Screen Television Case,Tv Protective Case Jiangsu Hengye Precision Technology Co.,Ltd , https://www.hengyejmtv.com
Intelligent vortex flowmeter is mainly used for measuring the flow of media fluid in industrial pipelines. Such as gas, liquid, steam and other media. It is characterized by low pressure loss, large measuring range, high accuracy, and almost no influence of parameters such as fluid density, pressure, temperature, and viscosity when measuring volume flow. No moving mechanical parts, so high reliability and low maintenance. Intelligent street flow meter parameters can be stable for a long time. The instrument uses a piezoelectric stress sensor, high reliability, can work in the operating temperature range of -10 °C ~ +300 °C. There are analog standard signal and digital pulse signal output. It is easy to use with digital systems such as computers. It is an advanced and ideal flow meter.
In general, the vortex flowmeter output signal (frequency) is not affected by changes in fluid properties and composition, which means that the meter factor is only related to the shape and size of the vortex generator and the Reynolds number. Its advantages are: simple and firm structure, convenient installation and maintenance; suitable for a variety of fluids, liquid, gas, steam and some mixed phases are applicable; high accuracy, generally about ± 1% R; wide range of flow, up to 10 : 1 or 20:1 or more; small head loss; no zero drift; relatively inexpensive price; disadvantage is: not suitable for low Re No. Re<20000, restrictions on the use of high viscosity, low flow rate, small diameter The requirements for the environment are relatively high, and places with vibrations should be eliminated as far as possible, and a long straight pipe section is required on the upstream side; the coefficient of the meter is lower, and the larger and lower the caliber, the lower. The signal resolution is reduced, so the caliber should not be too large, generally applied to DN15 ~ DN300mm.
What are the precautions before installing and using the vortex flowmeter? This article gives you a brief introduction.
First, the sensor no signal output online detection sensor no signal output, check the probe wiring and amplifier board wiring are found no problems, remove the amplifier board check there is no problem. There is still no signal after reinstalling. Tap the amplifier board and find the signal is sometimes missing, then conclude that the amplifier board components are virtually connected, check the solder joints, re-weld, and then install, debug, and normal.
During the inspection and commissioning process, it was found that the sensor was installed on the pipeline and the display instrument was installed in the control room. The two were not only far apart but also separated from each other. When the sensors were adjusted, they could not be seen directly from the display instrument.
Second, the sensitivity adjustment Smart Street Flowmeter has been adjusted and calibrated before delivery, but because the calibration medium and the actual medium is different, the calibration medium and actual conditions are also different, or the use of technical parameters provided by the unit is not very accurate, so the first time to install Make adjustments.
1. When there is no fluid flow in the pipeline, the display instrument should have no signal. If there is signal output, the sensitivity is too high. The sensitivity potentiometer needs to be turned counterclockwise to reduce the sensitivity.
2. When there is medium passing through the pipe and there is no signal or instability, you can lightly adjust the potentiometer to make it increase or decrease.
Third, the selection and installation of compensation devices The use of smart street flowmeter, generally should be stable in the air flow, temperature and pressure changes are not more accurate measurement, but the actual use is often not the ideal state, so the need for compensation devices. There are two kinds of compensation devices, namely pressure compensation and temperature compensation.
1. Pressure compensation. The pressure transmitter is more sensitive, but the price is higher. It can be installed on the sensor and downstream, and the installation distance is 1D~2D.
2. Temperature compensation. Due to the temperature compensation thermocouple or RTD, the response time is required, but the price is relatively low. It should be installed upstream of the sensor and installed vertically or reversely. The distance is 3D to 4D.
Fourth, simple correction The use of general smart street flow meter is continuous, the problem can not be removed when the inspection, this describes an online inspection method, this method is suitable for non-riot situations.
After the oscilloscope is calibrated, it is used to check. The oscilloscope wiring hook is connected with the signal line, and the ground is connected with the ground. To adjust the oscilloscope, a uniform square wave pulse signal should appear. The general manufacturer's instruction manual has the high and low level output regulations, from the oscilloscope display square wave high and low level values ​​to see if it is consistent with the specified value.