LUGB series vortex flow transmitter

The LUGB series vortex flow transmitter is mainly used for flow measurement of fluid media in industrial pipelines, such as gases, liquids, steam, and other media. Its characteristics are small pressure loss, large range, high accuracy, and almost unaffected by parameters such as fluid density, pressure, temperature, viscosity, etc. when measuring volumetric flow rate under working conditions. No movable mechanical parts, therefore high reliability and low maintenance. The instrument constant can remain stable for a long time. Plug in instruments are installed at the insertion port of the pipeline, while ball valves can be continuously loaded and unloaded. To facilitate regular cleaning and maintenance when operating in dirty media. This instrument uses piezoelectric stress sensors with high reliability and can operate within a temperature range of -20 ℃ to+250 ℃. It has both analog standard signals and digital pulse signal outputs, making it easy to use in conjunction with digital systems such as computers. It is a relatively advanced and ideal flow meter.

Characteristics

The output signal is not affected by the temperature, pressure, density, or composition of the fluid, and is proportional to the fluid flow rate.

The sensing element does not come into contact with the medium and has high reliability.

No movable parts, simple and sturdy structure.

Wide measurement range and high accuracy.

Low pressure loss and significant energy saving.

Working principle

When a cylindrical resistance body is vertically inserted into a fluid, vortices are alternately generated on both sides. As the fluid moves downstream, vortex columns are formed, known as Karman vortex streets, as shown in Figure 1. The resistance body that generates vortex streets is called a vortex generator. Experimental results have shown that the frequency of vortices is directly proportional to the flow velocity, which can be expressed as follows:

Experimental results have shown that when the distance h between two columns of vortices and the distance L between two vortices in the same column satisfy the formula L/h=0.281, an asymmetric vortex column can maintain a stable state. When the Reynolds number Re of the fluid is in the range of 5000-150000, Sr remains basically unchanged. Therefore, when d and Sr are constant, the frequency f of the vortex generator is proportional to the average flow velocity of the fluid, that is, proportional to the volume flow rate Q and independent of parameters such as pressure, temperature, density, etc.

When a vortex is generated on both sides of the cylinder, the sensor is subjected to alternating lift perpendicular to the flow direction to generate a signal. The frequency of the lift change is the vortex frequency. The sensor amplifies and shapes the signal through a converter to obtain a pulse signal that is linearly proportional to the flow velocity and outputs it directly or converts it into a 4-20mA standard signal output. The relationship between flow rate Q and frequency f is as follows: