Vortex flowmeter insertion type (with valve) intelligent meter head

Overview.

LUGB series vortex flow meter, is a velocity flow meter, mainly used for industrial pipeline fluid medium flow measurement, such as gas, liquid, steam and a variety of media measurement.

It is characterized by small pressure loss, a large range, high accuracy, in measuring the volume flow of working conditions almost independent of fluid density, pressure, temperature, viscosity and other parameters. No movable mechanical parts, so high reliability, low maintenance, instrument constants can be long-term stability. Among them, the insertion type vortex flowmeter, in the large pipeline welded base, and with the installation of ball valves, can be loaded and unloaded in a constant flow, so as to facilitate operation in dirty media and regular cleaning and maintenance.

The meter adopts piezoelectric stress sensor, can be used for a long time in the working temperature range of -20 ℃ to +300 ℃, widely used in petroleum, chemical, metallurgical, pharmaceutical, water treatment and other industries in the field of flow measurement and measurement and control work. The output of this instrument, there are analog standard signal, but also digital pulse signal output, easy to use with computers and other digital systems, is a more advanced, ideal flow meter.

◆Product implementation standard: JB/T9249-2015 (industry standard)

◆General flange standard: GB/T9119-2010 (national standard)

◆Type approval certificate: 2010F450-33 2006F414-33

Working principle.

When a columnar resistance body is inserted vertically in the fluid, vortices are generated alternately on both sides of it, moving in the downstream direction with the fluid, called Carman vortex street, see the figure below. The resistance body that generates the vortex street is called the vortex generator. Experimentally, it is proved that the frequency of vortex is proportional to the flow velocity, which can be expressed by the following equation：

Experiment proves that when the distance h between two columns of vortices and the distance L between two vortices in the same column meet the formula h/L = 0.281, the asymmetric vortex column can maintain a stable state. When the fluid Reynolds number Re in the range of 5000-150000, Sr is basically unchanged, so when the vortex generator column width d and Strohal number Sr for a fixed value of the vortex generator frequency transmission fluid is proportional to the average flow rate, that is, proportional to the flow Q and pressure, temperature, density and other parameters are not relevant.

When the vortex is generated on both sides of the column, the sensor is subject to the effect of alternating lift force perpendicular to the direction of flow induction signal, the frequency of change of the lift force is the vortex frequency, the sensor will send the signal to the converter to amplify and shape the pulse signal with the flow rate is linearly proportional to the direct output or will be converted to 4 ~ 20mA standard signal output, the relationship between flow Q and frequency is as follows：

当分体型电磁流量计零流量时，2个感应器发送和接收声波所需的时间相同（可具体测量零流量的技术），液体流动时，倒流方向的声波传送时间超过顺水方向的声波传送时间。其关联符合下面关系式：其中:V物质流速，θ为声束与液体流动方向的交角M为声束在液体的直线传播频次D为管道内径Tup为声束在正方向里的传播时间Tdown为声束在逆方向里的传播时间ΔT=Tup–Tdown，涡街流量计厂家根据上式测算出流速V，再通过大家输入到变送器里的管路数据D测算出流量。

超声波流量计Q值太低的原因以及解决方法：倘若在现场的安装没有难题的情况下，Q值低可能是由于待测管道中液体未满管、有气泡或附近负载规范含有变频和髙压机械设备造成的。