Detailed Explanation of the Principle and Features of External Level Gauges

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Principle of the ELL sonar-type external level gauge: 1. Principle of sonar ranging (patent number 82039). Sonar echo ranging technology (Sound Navigation And Ranging, abbreviated as “SONAR”) has a history of 100 years; it was invented in 1906 by Lewis Nixon of the British Navy and was first applied to submarines. This technology uses the reflection of sound waves in water to detect, measure the distance to, and locate underwater targets; it is the most reliable, widely used, and important technique in sonar engineering. The ELL sonar-type external level gauge measures the liquid level inside a tank from outside, by utilizing sonar echo ranging technology, thereby achieving a \"completely contactless\" method of external level measurement. The principle of sonar ranging is the basis for measuring liquid levels with ELL external level gauges, and this theoretical foundation is reliable. How to implement the theory? It works by having a level sensor attached to the bottom of the tank emit ultrasonic waves of a certain frequency. These ultrasonic waves penetrate the bottom wall of the tank and travel through the liquid inside it; they reach the liquid surface where they are reflected, generating an echo signal. This echo signal returns to the bottom of the tank, penetrates the bottom wall once again, and is detected by the same level sensor, which then sends it back to the main unit. The main unit analyzes the time taken from the emission of the ultrasonic waves to the formation of the echo signal, and uses the formula Height (H) = Speed (S) × Time (T) to calculate the liquid level. Among them, Height (H): liquid level height ； Speed (S): The speed at which sound waves propagate through a liquid medium; the speed of sound waves varies depending on the medium ； Time (T): The time it takes for sound waves to generate echoes in a liquid, determined by the host unit analyzing the echo signals received by the level measurement sensor. Schematic diagram of the principle of sonar ranging: https://bbs.hcbbs.com/forum.php?mod=image&aid=2130478&size=300x300&key=b966684fda470082&nocache=yes&type=fixnone 2. “Micro-vibration analysis” technology (patent number 1594973): This is a patented technology for measuring liquid levels externally, based on sound wave signal processing techniques. This type of acoustic signal processing technology is based on the application experience of Xi’an Dinghua Electronics’ external level gauges with nearly a thousand users around the world. Through the actual use of tens of thousands of such level gauges in hundreds of different operating conditions, and thanks to our more than 20 years of accumulation of data from industrial sites, we have been able to derive valuable knowledge and experience, which have led to the development of advanced judgment methods and algorithms. “The “micro-vibration analysis” technique is the guarantee for the stable measurement and reliable operation of ELL sonar-type external level gauges. Due to the complex operating conditions of some containers, such as: 1. The degree of impurity deposition within the container and the physical properties of different media ； 2. The too fast inlet and outlet speeds cause intense shocks, resulting in severe fluctuations in the liquid level inside the container ； 3. The medium has high volatility, resulting in a vapor-liquid mixture at the liquid surface. This results in the level measurement sensor receiving not only the echo signals from the liquid surface but also various other interference signals, which interfere with the instrument’s ability to determine the time at which the sound waves are reflected from the liquid surface and generate echoes ； Sound wave signals experience significant attenuation when passing through container walls ； The propagation speed varies in different liquid media, and it also changes when the temperature or density of the liquid medium changes; all these factors affect the accurate measurement of liquid levels. “The “micro-vibration analysis technology” overcomes these well-known challenges in the field of external level measurement through intelligent processing methods and advanced echo recognition algorithms. Its learning capabilities enable it to identify and reject interference signals such as residual seismic waves from the container walls, multiple echoes, and false echoes. Ensure effective tracking and monitoring of the echo signals returning from the liquid surface. 3. Automatic calibration technology (Patent No. 1523433) – The “Automatic Calibration Technology” is a patented technique that ensures accurate measurements by the ELL sonar-based external level gauge. When the temperature of the same liquid medium changes significantly, as well as when there are substantial changes in the liquid’s composition and density, this has a considerable impact on the propagation speed of sound waves within the liquid, leading to measurement errors. To ensure the accuracy of the instrument, it is possible to install a calibrator inside the container and add a level measurement probe dedicated to calibration; this calibration probe measures the standard length of the liquid column inside the calibrator, which is 1 meter. Since the calibration probe operates in the same way as the level measurement probe (using the principle of sonar echo ranging), the propagation speed of ultrasonic waves through the liquid in the calibrator can be determined using the formula: speed (S0) = distance (H0) / time (T0). Among them: Speed (S0): the sound wave propagation speed determined in real time ； Distance (H0): Liquid level height inside the calibrator ； Time (T0): The echo time of the liquid level inside the calibrator. Since the liquid in the calibrator is in communication with the liquid in the container, the temperature and composition of the liquid in the calibrator are identical to those of the liquid in the container, and the speed of sound propagation in both is the same. As a result, it is possible to determine the accurate speed of sound propagation in the medium inside the container under the current conditions. With S0 = S, this value can be used in the formula for calculating liquid level: Height (H) = Speed (S) × Time (T). The instrument automatically uses the corrected sound speed for calculations, and it is calibrated every 15 minutes; as a result, the liquid level measured is not affected by changes in the liquid’s temperature or composition. The principle of automatic calibration involves identifying a known length on the container that will be filled with the liquid medium inside it, thereby self-calibrating the propagation speed to ensure high-precision measurements under any conditions. If a calibrator cannot be installed in the container under any circumstances, the known diameter of the container can be used as a calibrator to achieve automatic calibration. https://bbs.hcbbs.com/forum.php?mod=image&aid=2130479&size=300x300&key=ffc2200610b88366&nocache=yes&type=fixnone 4. Technical advantages: From 1997 to 2007, recognized technical challenges in the field of external liquid level measurement were resolved, and the interference caused by the following factors on liquid level detection was eliminated: A. Residual vibrations of the container walls ； B. Multiple echoes ； C. False echoes ； D、Significant attenuation of sound wave signals when passing through the container wall ； E. Effect of changes in medium composition on sound speed. Ensures A: stable and reliable performance ； B. Accurate results ； C. Intelligent measurement. Enables external level gauges to function in various complex field conditions. Features of the ELL sonar-type external level gauge: 1. Suitable for harsh operating conditions: ultra-high pressure vessels, high-purity media. The functions of the ELL series of instruments are not affected by temperature or pressure, allowing for reliable measurements in complex conditions. Isolated level gauges are suitable for \"hazardous chemicals\" such as highly toxic substances, corrosives, strong acids, and strong bases” ； 2. For open tanks and vessels at atmospheric pressure, external level gauges can perform reliable level measurement without being affected by the surface conditions of complex liquid media ； 3. Easy installation and maintenance: ELL series instruments can be installed and maintained online, without the need to empty the tank, use open flames, or make any holes ； 4. The probe and instruments contain no mechanical moving parts, are tightly sealed to be isolated from the outside environment, thus preventing wear or corrosion; they are highly durable and reliable ； 5. Safe and environmentally friendly: no drilling required, no flanges needed, no additional leakage points ； No welding is required, so there is no risk of explosion. https://bbs.hcbbs.com/forum.php?mod=image&aid=2130480&size=300x300&key=75f61d3bb03de666&nocache=yes&type=fixnone