Vortex flowmeter temperature compensation one card-mounted 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, with analog standard signal, also has a 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 will be generated alternately on both sides of it, with the fluid moving in the downstream direction, 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：

Experimentally proven: 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 into a 4 ~ 20mA standard signal output, the relationship between flow Q and frequency is as follows：

防止安装在管道系统的至高点或带有随意出口的垂直管路上(流体往下流动)。

涡街流量计供应商针对张口或半满管的管路，流量计应安装在U型管段处。

充分考虑管内壁积垢情况，尽量选择无积垢的管道开展测量。确实无法满足时，需把积垢考虑为内衬以求较好的测量精度。

要确保测量点处的温度和压力在感应器可工作范围之内。

2个感应器务必安装在管路轴面的水平方向上，而且在轴线水平位置±45o范围内安装，以防止上端有不满管、气泡或下边有沉淀等现象影响感应器正常测量。假如受安装地点空间的限定而不能水准对称安装时，可在确保超声波明渠流量计管中上部分无气泡的条件下，竖直或有倾角地安装感应器。

选择管件匀称密致，便于超声波传送的管道。