The guided wave radar level gauge is a radar level gauge based on the time domain reflectometry (TDR) principle. The electromagnetic pulse of the radar level gauge propagates along the cable or probe at the speed of light. When encountering the surface of the measured medium, the radar level meter portion of the pulse is reflected back along the same form and the echo path to the pulse-emitting device, reflected by the receiver and the signal is converted within a distance meter level signal when the pulse encounters the material surface, and the transmitting means The distance to the surface of the measured medium is proportional to the propagation time of the pulse between them, and the height of the liquid level is calculated. The operating time can be converted into level signals via electronic components. In addition, the guided wave radar can also measure the interface between two different media and fully utilize the principle of different dielectric constants in different media.
The installation of the instrument will also affect the normal measurement of the instrument. A reasonable installation can ensure long-term reliable and accurate measurement of the instrument. The reflected pulse signal is conducted along the cable or rod probe to the electronics section of the instrument. The microprocessor processes this signal to identify the echo generated by the microwave pulse on the surface of the material. These steps are required during installation. Taking into account, reduce the impact of adverse factors in the installation environment.
1 Guided wave radar level gauge can be threaded connection, the length of the thread should not exceed 15mm, can also be installed in the short tube. Installation of short tube diameter 2′′ to 6′′ installation short tube height should be ≤100mm (the shorter the length of the thread and short tube, the more stable the measurement), if the installation of short tube is longer, ideally the short tube should be cut short, or The bottom is fixed with a cable probe and an insulated centering bracket is used to avoid contact between the cable probe and the end of the short tube.
2DN200 or DN250 short tube installation: When the guided wave radar needs to be installed in the short tube with diameter greater than 200mm, the short tube inner wall will produce echo, which will cause measurement error if the dielectric constant of the medium is low. Therefore, for a short pipe with a diameter of 200mm or 250mm, a special flange with “horn interface†needs to be selected.
3 When installing on a plastic tank, pay attention to whether it is cable or rod type. If you want the guided wave radar to work properly, the process connection surface should be metal. When the guided wave radar is mounted on a plastic tank, if the tank top is also a plastic or other non-conductive material, the instrument needs to be equipped with a metal flange. If a threaded connection is used, a metal plate is required.
4 guided wave radar installed in the waveguide is generally used rod probe sensor, rod probe should be installed on the installation of insulating concentric bracket to ensure that the rod probe and wave guide tube concentric, otherwise it will produce a strong false echo.
5 When the measuring range exceeds the maximum measuring range of the bar-type probe guided-wave radar, the guided-wave radar of the cable probe should be selected. At this time, the diameter of the waveguide should be greater than or equal to 6 〞 (DN150), otherwise it will produce a strong False echo.
The 6-pole probe and cable probe should be installed far away from the feeding port to avoid abrasion.
The 7-bar probe and the cable probe should keep a certain distance from the tank wall and the tank bottom, and can not contact the metal tank wall and the tank bottom;
8 When the tank wall adheres, the distance between the probe and the tank wall is at least 100mm ;
9 Minimum distance between probe tip and tank bottom: cable probe (150mm) ; rod probe ( 50mm ); coaxial rod probe ( 10mm ) ; rod probe and cable probe should be installed as far away as possible from the installed equipment 300mm Above, such as tuning fork brackets, so as not to be interfered with; choose an appropriate mounting position, to avoid bending the probe during installation or operation;
10 Before installation, check whether the probe is damaged. When installing, it is better to perform it in the empty position. In the outdoor installation, it is recommended to use such protective cover.
The above ten points are summaries of the installation experience of the company's engineers for many years. They are for reference only. Actual installation notes need to be weighed against the actual installation environment. The final interpretation right belongs to the company.
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