Application of Float Level Gauge and Principle of Float Level Gauge
Float level gauge is a magnetic floating ball as a measuring element. Through the magnetic coupling, the internal resistance of the sensor changes linearly. The intelligent converter converts the resistance change into a 4~20mA standard current signal and superimposes the HART signal output or local Liquid crystal display can display the percentage of the liquid level, 4~20mA current and liquid level value in the field. The remote control supply room can realize the automatic detection, control and recording of the liquid level. The instrument is suitable for the measurement of the liquid level in the industries such as petroleum, chemical industry, electric power, light industry, medicine, etc., as well as various medium pressure and pressure vessels, especially for the measurement of the liquid level of underground storage tanks and storage tanks.
First, the float level gauge function and application WEUQK-50/C magnetic float level gauge (hereinafter referred to as level gauge). Liquid level detection for liquid media in various pressurized (or open) reservoirs (columns, tanks, tanks, spherical vessels and boilers) in industrial processes. It can display the working conditions and level height of various liquids on the spot. With the liquid level transmitter, the position signal of the liquid level can be transmitted over a long distance. Through a certain electrical device to achieve automatic control and measurement of liquid level purposes.
The level gauge has direct reading characteristics of the in-place display. There is no need for multiple level gauge combinations. Has a single unit for full-scale measurement. The device has fewer openings, clear display, eye-catching signs, and intuitive readings. When the liquid level gauge is directly equipped with the display device, the intermediate transmission of signal detection of the system can be omitted, thereby improving the transmission accuracy thereof.
Second, the float level gauge working principle The level meter uses the principle of the connected device. The liquid level in the container is introduced into the main tube of the level gauge. The floating ball assembly in the main tube is based on the buoyancy principle and the magnetic coupling principle. Outside the body tube, a column that reflects the magnetic phenomenon is attached as a display of the liquid surface position. With the change of the liquid level in the stylistic tube, the level of the float assembly also changes accordingly. So that the main body of the column for the flip of the 180-degree flip, when the liquid level rises, turn the column from white to red, when the liquid level drops, turn the column from red to white. The red and white boundaries of the display are the actual height of the media level in the container. In order to achieve the liquid level detection purposes shown in Figure 1, the main technical parameters of the float level gauge 1, the measurement range: 0-300mm, 0-6000mm
2, measurement accuracy: ± 10mm
3, medium density: ≥ 0.5g/cm3
4, working pressure: 1.0,1.6,2.5,4.0MPa
5, working temperature: A = 80 °C, B = 120 °C, C = 300 °C
6, medium viscosity: ≤ 0.4Pa.S (under medium conditions, L for high viscosity or low temperature, easy to use crystal heating medium jacket)
7, the proportion of measurement boundary difference: ≥0.15g/cm3
8, factory factory connection flange size: DN20PN2.5 (metric pipe)
9. The connection flange adopts the HG20592-20635-97 flange standard issued by the Ministry of Chemical Industry in 1998. If other flange standards are used, please specify when ordering. Flange connection hole distribution shape: square.
Fourth, the characteristics of float ball level meter 1, suitable for liquid level measurement of the liquid medium in the container In addition to the scene display, but also with remote transmitter, liquid level controller and other functions 2, the display is intuitive and eye-catching, display direction can be based on The user requested to change the display direction.
3, the measurement range is large, not limited by the height of the container.
4. The display assembly is completely isolated from the measured medium, so the seal is reliable and safe.
5, simple structure, easy installation, easy maintenance.
6, corrosion resistance, explosion-proof.
Fifth, the float level gauge related parameters use anti-corrosion materials (Table 1)
Domestic and foreign commonly used stainless steel material comparison table (Table 2)
Liquid medium density and sink distance (Table 3)
Selection examples:
Measure one accommodating vessel, working pressure 0.6MPa; t=80°C Measuring range: 2000mm. The medium is light oil (0.8% specific gravity) and requires corrosion-resistant material (1Cr18Ni9Ti), flat welded flange. With drain screw. The upper junction box type (explosion proof) output 4-20mA. Side-mounted type: UHZ-50/C1 1GL-3D-2000-0.6-80°C-0.8
Seven, float ball level meter structure and dimensions
1, the basic type (Figure 2a) 
2, jacket type (Figure 2b) 
Eighth, floating ball level meter application notes 1, the side-mounted liquid level and the measured container up and down the liquid separator between the most installed a cut-off valve to open or collect the level gauge, on the other hand to bring the maintenance level Convenience. When the upper and lower shut-off valves are closed, the bottom drain flange of the level gauge can be opened or the drain screw can be removed, and the main body of the level gauge can be cleaned by injecting clean water.
2, install the level gauge, flange center line perpendicularity ∠4 ‰, when the gauge measurement range is greater than 3 meters, you need to consider increasing the middle reinforcement flange (or ear climbing) as a fixed support to increase strength.
3. The cross-sectional area of ​​the core wire connecting the remote liquid level transmitter and the secondary instrument should be greater than 0.8mm2. When laying parallel with the AC power supply, at least 20cm distance should be maintained. Iron pipe laying, or laying with two core cables, the layer can only be grounded at one end.
4. The liquid level controller is selected, and the contact capacity of the liquid level controller is designed for resistive loads. If non-resistive or high-power loads are used, intermediate relays are used for conversion.
5, for liquid media containing suspended impurities and magnetic substances, should not use the level gauge (because these impurities will block the float assembly)
6. The “L1†in the outline structure diagram is the “sink distance†of the side-mounted level gauge. The parameter must be understood by the user. This parameter is related to the density of the medium. According to the principle of buoyancy, the length of the float assembly is related to the density of the medium. In the selection and design must consider different media have different L1 detailed parameters in Table 3 (for reference only)
Nine, the installation and maintenance of the float level gauge 1, the installation of the level gauge must be vertical to ensure that the float assembly can move up and down freely in the main tube.
2. It is advisable to install a shut-off valve between the container and the level gauge to facilitate cleaning and maintenance of the liquid level and cut off the material.
3. The proximity of the magnetizer is not allowed around the main tube of the level gauge, otherwise it will directly affect the normal operation of the level gauge.
4. After the installation of the liquid level gauge, it is necessary to use magnetic steel for correction, and guide the column once to make red below the zero position and white above the zero position.
5. When the level gauge is put into operation, the lower inlet valve should be opened to allow the liquid medium to enter the main tube smoothly, avoiding the liquid medium with the floating ball assembly to rise rapidly, causing the column to turn black and failing or turning over (if this phenomenon occurs) After the level of decay is stable, the steel can be recalibrated.)
6. In order not to damage the float ball assembly during transportation, the float ball assembly is taken out of the main body of the small liquid level gauge before leaving the factory. After the liquid level gauge is installed, open the bottom drain flange and reinstall the float ball assembly into the main tube. Note that the weight of the float assembly is upward and cannot be flipped.
7. According to the condition of the medium, the sewage cleaning flange can be periodically opened to clean the precipitation of the main body of the pipe.
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