In today’s industrial landscape, the need for accurate and reliable level measurement in various applications is paramount. This is where radar level sensors come into play, offering a robust and versatile solution for monitoring the level of liquids and solids in tanks and vessels. Understanding radar level sensors and their capabilities is crucial for selecting the ideal sensor that aligns with your specific requirements. This article delves into the intricacies of radar level sensors, providing a comprehensive guide to assist you in mastering the art of selection and finding the perfect radar level sensor for your needs.
Understanding Radar Level Sensors
Radar level sensors are advanced instruments designed to measure the level of substances within a container or vessel using radar technology. They are widely utilized in industries such as oil and gas, chemical processing, water treatment, and food and beverage, where accurate level measurement is essential for operational efficiency and safety. These sensors operate based on the principle of emitting microwave signals towards the surface of the substance being measured and then receiving the reflected signals to determine the level. The time taken for the microwave signals to travel to the surface and back enables the sensor to calculate the distance and provide an accurate level measurement.
Radar level sensors offer distinct advantages over traditional level measurement technologies, such as ultrasonic and capacitance sensors. They are unaffected by temperature, pressure, or vapors, making them suitable for harsh and challenging environments. Additionally, radar sensors can measure levels with high accuracy, even in the presence of dust, foam, or agitated surfaces. Understanding the underlying technology and capabilities of radar level sensors is crucial for making an informed decision when selecting the most suitable sensor for a specific application.
Types of Radar Level Sensors
Radar level sensors can be categorized into two primary types: guided wave radar (GWR) sensors and non-contact radar sensors. Guided wave radar sensors utilize a probe or rod that extends into the substance being measured, providing direct guidance for the radar signals. These sensors are suitable for applications where the substance has dielectric properties that can affect signal propagation. On the other hand, non-contact radar sensors, also known as free-space or airborne radar sensors, emit radar signals directly into the container without the need for physical contact with the substance. This type of sensor is ideal for measuring levels in open or closed vessels without the limitations of probe-based systems.
Understanding the distinctions between guided wave radar and non-contact radar sensors is essential for determining the most appropriate type of radar level sensor for a specific application. Factors such as the characteristics of the substance, vessel design, and environmental conditions play a significant role in the selection process, highlighting the importance of evaluating the advantages and limitations of each sensor type.
Factors to Consider When Choosing a Radar Level Sensor
Selecting the right radar level sensor involves a thorough consideration of various factors to ensure optimal performance and reliability. The first factor to assess is the physical properties of the substance being measured, including its dielectric constant, conductivity, and temperature. These properties influence the choice between guided wave radar and non-contact radar sensors, as well as the selection of suitable antenna materials and signal frequencies. Additionally, vessel dimensions, nozzle configurations, and process conditions must be carefully evaluated to determine the most suitable mounting and installation options for the radar sensor.
Environmental factors such as temperature extremes, corrosive atmospheres, and potential mechanical impacts should also be taken into account when choosing a radar level sensor. The sensor’s ingress protection (IP) rating, material construction, and compliance with industry standards are critical considerations to ensure long-term reliability and safety in challenging operating environments. Furthermore, factors such as measurement range, accuracy requirements, and communication interfaces play a pivotal role in the selection process, as they directly impact the sensor’s ability to provide precise and timely level measurements.
Antenna type of radar level sensor
The antenna is an important part of the radar liquid level gauge to measure the liquid level. The selection of the radar liquid level gauge mainly lies in selecting the appropriate antenna type. There are three main types of non-contact radar level gauge antennas: horn antenna, parabolic antenna and planar antenna.
Horm antenna- The horm antenna adopts the point source transmission method, and the radar wave is a divergent spherical wave, which is mainly used for the liquid level measurement of the vaulted tank that does not need a wave guide tube. Since the entire bell antenna is in the storage tank and has almost the same temperature as the tank environment, it is possible to prevent condensation from occurring in the antenna.
Parabolic antenna- The parabolic antenna also uses the point source transmission method, and the radar wave is a divergent spherical wave, which allows installation near the tank wall. Usually used in vaulted tanks, the medium is mainly waxy oil, residual oil, asphalt and other viscous and condensable high-temperature oil products. The bottom of the storage tank is equipped with heated steam coils. The steam generated in the tank at high temperature (about 200 ℃) makes it easy to form condensate and hang material at the radar antenna, which affects the accurate measurement of the radar level gauge. Condensation and hanging material phenomenon appeared. Moreover, the narrow beam of the parabolic antenna makes the radar wave energy more concentrated and the focus is good, which can ensure high measurement accuracy.
Planar antenna- Planar antenna technology (also called array antenna technology) uses a multi-source transmission method. Compared with a single-point source, its measurement is based on a plane rather than a certain point, so the radar wave emitted is a plane spiral wave. Mainly used for liquid level measurement of the inner (outer) floating roof tank installed with a waveguide. The radar wave emitted by the planar antenna has the characteristics of narrow beam and concentrated energy, so the energy of the part in contact with the waveguide tube wall is very small, and the influence of the roughness of the inner wall of the waveguide is also very small, and the influence of the oil wall on the measurement small.
Selection of different containers and different media
Radar level transmitter has the advantages of low maintenance, high performance, high precision, high reliability, and long service life. When measuring the liquid level of a container, it is affected by many external conditions such as the shape, size, diameter, and material of the container, as well as the physical and chemical characteristics of the medium such as steam, foam, and corrosive volatility.
Installation requirements and selection of different containers- If it is in an open pool, jug, or natural water, it will have no effect on the radar used. All three can be used. In a closed container, the guided wave radar level gauge can be installed on the DN40 take-off, and the low-frequency horn radar and high-frequency horn can be installed on the DN50 take-off, provided there is no stirring, foam, steam, pump Vacuum, if these conditions exist, the high frequency radar should be installed with DN100 flange, and the low frequency radar should be installed with DN150 flange.
corrosive liquids- The flange and cable of the guided wave radar level sensor are 304ss material by default. 316L material can be used for general corrosive liquids, and PTFE can be used for strong corrosive liquids such as hydrochloric acid and nitric acid.
When encountering strong corrosive liquids such as hydrochloric acid and nitric acid, low frequency rod radar and high frequency rod radar are more suitable. Both of these radars are designed for use in highly corrosive environments. It should be noted that the low frequency rod radar has a relatively large blind zone, 0.5-0.7 meters, which is not suitable for small pots.
Foamy liquid- There is no more than 2 cm of foam on the surface of the liquid, which has little effect on the measurement. For foams of more than 2 cm, pay attention to the thickness of the foam and the size of the foam. In foams measuring more than 2 cm, small foams are less likely to be penetrated by radar electromagnetic waves than large foams. At the same thickness, the thicker the foam, the less likely to penetrate. In this case, the use of low-frequency horn radar is more suitable than high-frequency horn radar. If it is a non-adhesive foam, then the use of guided wave radar level gauge can easily penetrate the foam, and accurately measure the liquid level below the foam.
You can also consult our team for model selection for your tank radar level measurement solutions.
Guided Wave Radar Level Sensors vs. Non-Contact Radar Level Sensors
The choice between guided wave radar (GWR) and non-contact radar level sensors depends on the specific characteristics of the substance being measured and the operational requirements of the application. Guided wave radar sensors are well-suited for measuring the level of liquids and solids with varying dielectric constants, including those with low reflectivity or extreme temperatures. Their probe-based design allows for direct guidance of the radar signals, enabling accurate measurements in challenging conditions where non-contact sensors may encounter limitations.
Non-contact radar level sensors, on the other hand, offer advantages in applications where physical contact with the substance is impractical or where vessel design and process constraints necessitate a free-space measurement approach. These sensors are capable of measuring levels in open or closed vessels without the need for intrusive probes, making them versatile and suitable for a wide range of applications. Understanding the specific advantages and limitations of guided wave and non-contact radar sensors is essential for making an informed decision that aligns with the unique requirements of each level measurement application.
Choice between radar level Sensor and guided wave radar level Sensor
First let’s look at the difference between radar level gauge and guided wave radar level gauge
The contact method: the radar level gauge is non-contact, and the waveguide level gauge is contact-type. That is to say, the pilot type cannot be used in the occasions where the food grade requirements are high.
The working medium: the guided wave radar level gauge needs to consider the corrosivity and adhesion of the medium, and the installation and maintenance of the excessively long guided wave radar is more difficult. In the case of low dielectric constant, the measurement principle of radar or guided wave radar is based on the difference in dielectric constant. Because the waves emitted by ordinary radar are divergent, when the dielectric constant is too low, the signal is too weak to measure. Stable, while the guided wave radar wave propagates along the probe with relatively stable signals. In addition, the general guided wave radar also has a bottom detection function, which can be corrected according to the measured value of the bottom echo signal to make the signal more stable and accurate.
The type selection: ordinary radars can be used interchangeably, and guided wave radars cannot be used interchangeably because the length of the probe (cable) is fixed according to the original working conditions. Therefore, the selection of guided wave radars is more troublesome than ordinary radars.
The measurement range: ordinary radar is more commonly used on tanks of 30 and 40m, even measuring 60m. Guided wave radar also needs to consider the force of the probe (cable). It is also because of the force that the measurement distance of the guided wave radar is generally not very long. However, the guided wave radar has obvious advantages in some special working conditions, such as stirring in the tank and large medium fluctuations. The measured value of the guided wave radar fixed at the bottom of such working conditions is more stable than the flexible radar; For level measurement, because the installation measurement space is small (or there are many interferences in the tank), general radar is not suitable. At this time, the advantages of guided wave radar are revealed.
Tips for Optimizing the Performance of Radar Level Sensors
After selecting and installing a radar level sensor, optimizing its performance is essential for maximizing the benefits of accurate and reliable level measurement. One key tip for optimizing radar level sensor performance is to regularly calibrate the sensor based on the specific substance properties and process conditions. Calibration ensures that the sensor’s measurements remain accurate and consistent, accounting for any variations in the substance characteristics or environmental factors.
Maintaining proper antenna alignment and ensuring unobstructed radar signal propagation are also essential for optimizing sensor performance. Any misalignment or obstructions that interfere with signal transmission can lead to inaccurate measurements and compromised operational efficiency. Additionally, leveraging advanced signal processing features and software capabilities provided by the sensor manufacturer can enhance the sensor’s ability to adapt to challenging conditions and deliver reliable measurements.
Conclusion
Mastering the art of selection when it comes to finding the ideal radar level sensor for your specific needs requires a comprehensive understanding of radar level sensor technology, types, factors to consider, model selection, key features, common mistakes to avoid, and optimization tips. By carefully evaluating the unique requirements of each level measurement application and considering the diverse capabilities and performance characteristics offered by different radar level sensor models, industries can ensure the successful and effective deployment of radar sensors for accurate and reliable level monitoring. Ultimately, the art of selection empowers industries to leverage the advanced capabilities of radar level sensors and enhance operational efficiency, safety, and productivity.
