About the selection principle of guided wave radar level gauge

   How to know how much you know about the selection of guided wave radar level gauges? The editor has sorted out a few items for this product, and see which four aspects determine the principles of guided wave radar level gauge selection:

    1. Process conditions. Including: upper and lower medium density and dielectric constant, as well as the state of the medium surface, which are the prerequisites for judging the selection of guided wave radar level gauges. As a very important process parameter, the dielectric constant has two main effects on electromagnetic waves: first, it affects the absorption rate of electromagnetic waves on the surface of the medium, also called reflectivity; second, when electromagnetic waves pass through the medium, the wave speed of electromagnetic waves is not According to the wave speed equal to the wavelength multiplied by the frequency, it can be known that when the surface of the medium is contacted, the wavelength and the frequency change and are inversely proportional. The higher the value of the dielectric constant, the stronger the reflection. The electromagnetic wave reflectivity is affected by the following conditions: the attenuation coefficient is proportional to the square root of the conductivity σ and the magnetic permeability μ, and inversely proportional to the square root of the dielectric constant ε. That is to say, the larger the dielectric constant of the target object, the smaller the attenuation rate, and the larger the reflectivity, so the dielectric constant is large, the reflectivity is strong, and the signal strength is high. Conversely, a medium with a small dielectric constant has a large attenuation rate, a small reflectivity, and a weak signal strength. The dielectric constant does not affect the measurement results, but only affects the amplitude of the echo, which can improve the measurement performance and reliability of the guided wave radar.

    2. Selection of guided wave radar level gauge body:

    a) Select the appropriate probe according to the size of the measurement range.

    b) Select the correct probe according to the working temperature range. The applicable range of the probe is -196 ~ 400 ℃, and the probe of high temperature and high pressure, normal temperature and normal pressure or low temperature can be selected according to the working conditions.

    c) Process connection seals, that is, the material selection of the O-ring should meet the characteristics of working temperature, pressure and medium.

    3. Transmitter part. It is mainly to choose top loading or side loading according to the characteristics of the container. The guided wave radar is installed on the top of the equipment, and the size of the upper opening is generally 150mm. While the guided wave radar is installed on the side of the device, the opening size is slightly smaller, generally 50mm or 80mm. In the engineering selection, the guided wave radar on the vertical tank is often installed on the side. On the horizontal tank, according to the size of the equipment, the top or side can be installed with openings. For underground storage tanks, in order to facilitate observation, the guided wave radar should be installed on the top. The instrument selection should be based on the division of hazardous areas to determine whether the instrument is intrinsically safe or flameproof. Choose whether the power supply is 24V (DC) or 200V (AC) according to the cable routing length and the normal working voltage of the instrument. Taking the intrinsically safe type as an example, the working current of the guided wave radar level gauge is about 150mA, the working voltage is 16V (DC), the conventional 7-core strand cable is selected, and the wiring route is assumed to be 1000m. After calculation, the line voltage drop is within 2~4V Therefore, 24V (DC) external power supply is selected, which fully meets the working voltage requirements of the guided wave radar level gauge. This selection is widely used in petrochemical plants.

    4. Instrument accessories. Mainly include: separation indicator, guide tube, outer cylinder, lightning protection, etc., according to needs, consider whether to configure:

    a) According to the process requirements, the guided wave radar is equipped with a separation indicator, which is installed in a place where it is easy to observe.

    b) When there is disturbance in the equipment, or the steam medium interferes with the measurement, the guided wave radar can be equipped with a guide tube, which can not only play a role in stabilizing the liquid, but also increase the anti-interference ability.

    c) An outer cylinder is required for the guided wave radar to be installed on the equipment side. The process connection between the guided wave radar and the outer cylinder has two forms: flange and thread. The installation form is similar to that of the float level gauge installed on the equipment side.

    Therefore, I have compiled four points for the selection above, hoping to help everyone. Of course, our Weihai Kunke Flow Meter Co., Ltd. has a professional business manager who can give you the best recommendations. For more information, please log in to Weihai Kunke's official website at any time for detailed inquiries. Are the brands of natural gas flow meters good or bad?