Guangzhou Dechuan Flow Meter Co., Ltd.   

The LUGB series flowmeter is mainly used for measuring the flow of industrial pipeline media fluid, such as gases, liquids, vapors and other media. It is characterized by low pressure loss, wide range and high accuracy. It is almost not affected by parameters such as fluid density, pressure, temperature, viscosity and so on. There are no movable parts, so the reliability is high and the maintenance quantity is small. Instrument parameters can be stable for a long time. The vortex flowmeter adopts piezoelectric stress sensor, which has high reliability and can work in the working temperature range of -20 to +250 C. It has analog standard signal and digital pulse signal output. It is easy to match with computer and other digital systems. It is an advanced and ideal flow meter.
Vortex flowmeter principle
In the fluid, a triangular columnar vortex generator is generated. The regular vortex is generated alternately from both sides of the vortex generator. The vortex is called Carmen vortex. As shown in the right picture, the vortex is arranged asymmetrically downstream of the vortex generator.
The frequency of the vortex is f, the average velocity of the measured medium is, the width of the inlet surface of the vortex generator is D, the body diameter is D, the following formula can be obtained:
F=SrU1/d=SrU/md (1)
The mean velocity of both sides of U1-- vortex is m/s.
Sr-- Straw Haar number;
Ratio of arcuate area on the two sides of m-- vortex generator to cross section area of pipeline
The volume flow in the pipe is QV.
Qv= PI D2U/4= PI D2mdf/4Sr (2)
K=f/qv=[PI D2md/4Sr]-1 (3)
The meter coefficient and pulse number /m3 (P/m3) of the K-- flowmeter.
K is not only related to the geometry of the vortex generator and pipeline, but also related to the Straw Haar number. The Straw Haar number is a dimensionless parameter, which is related to the shape of the vortex generator and the Reynolds number. Figure 2 shows the relationship between the Straw hAHR number and the Reynolds number of the cylindrical vortex generator. It can be seen from the diagram that Sr can be regarded as a constant in the range of ReD=2 * 104~7 * 106, which is the normal working range of the instrument. When measuring gas flow, the flow rate of LUGB is (4).
Fig. 2 Relationship between Straw Haar number and Reynolds number
The qVn and qV-- in the formula are respectively the standard volume (0oC or 20oC, 101.325kPa) and the volume flow under the working condition, m3/h.
Pn, P-- are absolute pressure under standard condition and working condition, Pa respectively.
Tn and T-- are respectively thermodynamic temperature and K under standard condition and working condition.
Zn and Z-- are respectively gas compression coefficients under standard condition and working condition.
It can be seen from the above formula that the pulse frequency signal output by VSF is not affected by the change of fluid physical properties and components, that is, the instrument coefficient is only related to the shape and size of the vortex generator and pipeline in a certain Reynolds number range. However, as the flowmeter needs to detect mass flow in material balance and energy metering, the volume and flow density of the flowmeter should be monitored at the same time, and the physical properties and components of the flowmeter will have a direct impact on the flow measurement.
Vortex flowmeter is a new flowmeter based on Carmen vortex principle for measuring fluid flow in closed pipes. Because of its good medium adaptability, without temperature and pressure compensation, it can directly measure the volume, flow rate of steam, air, gas, water and liquid. Equipped with temperature and pressure sensors, it can measure the volumetric flow rate and mass flow rate. It is an ideal substitute product for throttling flowmeters.
To improve the high temperature and vibration resistance of vortex flowmeters, our company has developed an improved SDLUG vortex flow sensor recently. Because of its unique structure and material selection, the sensor can be used at high temperature (350 degree) and Qiang Zhendong (less than 1G).
In practical applications, the maximum flow rate is much lower than the upper limit of the instrument. With the change of load, the minimum flow rate will often be lower than the lower limit of the instrument. The instrument is not working in its optimum working section. In order to solve this problem, it is usually used to reduce the diameter at the measuring point to increase the flow velocity at the measuring point, and select smaller caliber instruments to facilitate the measurement of the instrument. However, this way of reducing the diameter must be rectified in the straight pipe section with a length of 15D or more between the variable diameter tube and the instrument, so that the processing and installation are inconvenient. The LGZ variable diameter rectifier developed by our company is circular, and has many functions, such as rectification, increasing the velocity of flow and changing the velocity distribution. Its structure size is small, it is only 1/3 of the inner diameter of the process tube. It is integrated with the vortex flowmeter. It not only needs no additional straight pipe section, but also reduces the requirement for the straight pipe section of the process pipe. The installation is very convenient.
In order to facilitate the use, the battery powered local display vortex flowmeter is powered by micro power consumption. The lithium battery can run continuously for more than one year. It saves the cost of installation and installation of cables and display instruments, and can display instantaneous flow and cumulative flow in situ. The temperature compensated one type vortex flowmeter also has a temperature sensor, which can directly measure the temperature of saturated steam and calculate the pressure, thus displaying the mass flow rate of saturated steam. Temperature and pressure compensation is a kind of sensor with temperature and pressure. It can directly measure the temperature and pressure of the gas medium for gas flow measurement, thus displaying the volumetric flow rate of the gas.
Measuring medium: gas, liquid and vapor.
Caliber flange caliper caliber 25,32,50,80100
Flange joint diameter selection 100150200
The range of flow measurement is normal, the Reynolds number is 1.5 * 104~4 * 106, the gas is 5 ~ 50m/s, and the liquid is 0.5 ~ 7m/s.
Normal measuring flow range, liquid and gas flow measurement range is shown in Table 2; steam flow range is shown in Table 3.
Measurement accuracy 1 level 1.5.
Temperature of measured medium: room temperature - 25 ~ 100 C
High temperature - 25 -25 ~ 150 C, 250 C
Output signal pulse voltage output signal high level 8 ~ 10V low level 0.7 ~ 1.3V
The pulse duty ratio is about 50%, and the transmission distance is 100m
The pulse current remote transmission signal is 4~20 mA, and the transmission distance is 1000M
The ambient temperature of instrument is -25 ~ +55 C humidity: 5 ~ 90% RH50 C
Material: stainless steel, aluminum alloy
Power DC24V or lithium battery 3.6V
Explosion proof grade intrinsically safe iaIIbT3-T6
Protection level IP65