Essential Tips | 100% Must-Know Facts About Radar Level Meters!

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Radar level gauges originated in the mid-1960s; they are level measurement instruments that utilize microwave measurement technology. In the initial stage, it was mainly used for measuring the oil level in marine vessels ； Due to overcoming the many disadvantages of previously used mechanical contact-type level gauges, such as difficulties in cleaning and inconvenience in maintenance, they were subsequently used for measuring the level in onshore storage tanks as well as in refining plants. With the continuous development of the petrochemical industry, radar level gauges are being used in an increasingly wide range of applications. Their high precision has been recognized by international metrological organizations, meeting the requirements for measuring materials in trade transactions. The measurement principle of radar level gauges: Radar level gauges operate on a transmit-reflect-receive principle. Ultra-high frequency electromagnetic waves are sent from an antenna toward the liquid surface of the container being measured. When these electromagnetic waves reach the liquid surface, they are reflected back and captured by the same antenna. By determining the time difference between the emitted wave and the echo, the height of the liquid surface can be calculated. The antenna of the radar level gauge emits electromagnetic waves, which are reflected by the surface of the object being measured before being detected by the antenna again. The time it takes for these electromagnetic waves to travel from emission to reception is proportional to the distance to the liquid surface; the relationship is given by: D = CT/2, where D is the distance from the radar level gauge to the liquid surface, C is the speed of light, and T is the time taken for the electromagnetic waves to travel. By recording the time it takes for the pulse waves to travel, and since the speed of propagation of the electromagnetic waves is constant, it is possible to calculate the distance from the liquid surface to the radar antenna, thereby determining the liquid level. http://img68.ybzhan.cn/9/20191119/637097585364696123842.png Structure of the radar level gauge: The radar level gauge consists of three components – the main unit, the connection flanges, and the antenna. The main unit of a radar level gauge also includes a microwave signal source and a signal processing section. During operation, the microwave signal source outputs a linearly modulated microwave signal with a constant amplitude; the transmission frequency increases linearly over time, with a slope of k. When this continuous wave reaches the liquid surface, it arrives after a certain delay relative to the transmitted signal. Connection flanges are used for the process connection of radar level gauges, and standards GH/T20592 or GH/T20615 are typically applied. As the third component of a radar level gauge, the antenna is primarily used for transmitting and receiving radar electromagnetic wave signals. Antennas adopt different structural forms depending on the specific operating conditions of the user. Including: rod type, embracing type, trumpet type, stick type, flat plate type, and so on. Classification of radar level gauges: Radar level gauges are divided into contact-type radar level gauges and non-contact radar level gauges, depending on their measurement method. Contact radar level gauges are mainly used in applications with a small measurement range and where the medium is non-corrosive. The installation method is shown in the following image: http://img69.ybzhan.cn/9/20191119/637097585686538564620.png Since the antenna of a contact-type radar level gauge inevitably comes into contact with the medium inside the tank, it is not suitable for use in environments with high corrosivity or high purity. Additionally, if the medium in the tank fluctuates sharply, it is also not suitable for contact-type radar level gauges. Contactless radar level gauges have a wide range of applications, and can measure distances up to 80 meters. It is also unaffected by factors such as the composition, concentration, pressure, and temperature of the medium inside the tank. The installation method is as shown in the following image: http://img68.ybzhan.cn/9/20191119/637097585850657928631.png