What points should be paid attention to for Ultrasonic level transmitter installation? Ultrasonic level transmitter is a widely used non-contact/non-invasive liquid level meter. Including wastewater storage tanks, fuel storage tanks, wastewater treatment pools, etc. Connect to the display table or various DCS systems through 4~20mA or RS485 (Modbus protocol or other customized protocols). Provide real-time liquid level data for industrial automation.
Let’s take a look at the Ultrasonic level transmitter installation requirements and what the installation principles are.
Ultrasonic level transmitter working principle and frequency range
Ultrasonic level transmitter is a cost-effective liquid level measuring instrument. It is mainly composed of three parts: transducer, electronic module and housing. The transducer is one of the core components, and the working frequency of the transducer is one of the important parameters.
Ultrasonic pulses are emitted by sensors (transducers) during the measurement. The sound waves are reflected by the liquid surface and picked up by the same sensor. Converted into electrical signals by piezoelectric crystals. And the distance between the sensor and the surface of the liquid to be measured is calculated by the time between the emission and reception of the sound wave.
The selection of the operating frequency of the ultrasonic transducer is a very important parameter. It is not only directly related to the frequency characteristics and directional characteristics of the transducer. It also affects important performance indicators such as the transmitting power and transmitting efficiency of the transducer. In general, the working frequency of the ultrasonic level gauge is consistent with the working frequency of the ultrasonic transducer.
Working frequency is an important parameter of ultrasonic liquid level gauge. During the production of each ultrasonic sensor of Sino-Inst, the working frequency and impedance characteristics of the transducer are strictly measured and recorded to ensure product quality.
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Principles of Ultrasonic Level Transmitter installation
When you’re installing an Ultrasonic Level Transmitter, in addition to meeting the installation requirements, there are certain principles to consider:
- The distance from the probe’s emission surface to the low liquid level should be less than the range of the purchased transmitter.
- The distance from the probe’s emission surface to the high liquid level should be greater than the blind zone of the purchased transmitter.
- The probe’s emission surface should remain parallel to the liquid surface.
- The location of the probe’s installation should ideally avoid areas directly below inlets and outlets where the liquid surface experiences significant fluctuations.
- If the pool or tank wall is not smooth, the transmitter’s installation location should be more than 0.3m away from the wall.
- If the distance from the probe’s emission surface to the high liquid level is less than the blind zone of the purchased transmitter, an extension tube should be installed. The extension tube should have a diameter greater than 120mm, and a length between 0.35m and 0.50m. It should be installed vertically, have a smooth inner wall, and the opening in the tank should be larger than the extension tube’s inner diameter. Alternatively, the tube can extend to the bottom of the tank and should have a diameter greater than 80mm. Holes should be left at the bottom of the tube to keep the internal liquid level of the extension tube at the same height as inside the tank.
Basic Requirements for Ultrasonic Level Transmitter Installation
Before installing an ultrasonic level transmitter, make sure the instrument model meets the environmental requirements of the site, such as process pressure, process temperature, and chemical properties of the medium. This will ensure normal operation after installation.
Ultrasonic level transmitters have a certain emission angle when transmitting ultrasonic pulses. There should be no obstacles within the radiating area of the emitted ultrasonic beam from the lower edge of the ultrasonic transducer to the surface of the medium being measured. This requires avoiding internal facilities such as ladders, heating equipment, and limit switch brackets during installation.
Moreover, note the following when installing an integrated ultrasonic level transmitter:
- Because of the sound beam angle, the ultrasonic beam should not intersect with the feed flow. Therefore, do not install the integrated ultrasonic level transmitter above the feed flow to ensure measurement of the medium surface and not the feed flow. Make sure the highest material level does not enter the measurement blind zone during installation.
- The integrated ultrasonic level transmitter must maintain a certain distance from the tank wall.
- The installation of the integrated ultrasonic level transmitter should aim to keep the transducer vertical to the liquid surface.
- When installing the instrument outdoors, sunshade and rain protection measures should be adopted to avoid direct sunlight and reduce measurement errors caused by temperature changes.
- The integrated ultrasonic level transmitter installed in hazardous areas must comply with national explosion-proof hazardous area installation regulations. In places where explosion-proof requirements are needed, the ultrasonic level transmitter must be grounded.
Other Requirements for Ultrasonic Level Transmitter Installation
- Installation location: Keep the integrated ultrasonic level transmitter at least 200mm away from the tank wall. For a conical container with a flat tank top, install the instrument at the central position of the container top. This ensures measurement to the bottom of the container. For an arch-shaped tank, install it at 1/2 or 2/3 of the tank top radius. For trenches, take into account the load-bearing capacity of the bracket when installing. The probe emission angle should not exceed the A point boundary. The installation height must be within the range.
- Moisture proofing: If the instrument is installed outdoors, in a humid indoor environment, or on the top of a refrigeration or heating tank, the environment is humid. Rainwater and condensation can flow down. To prevent moisture, before connecting the cable, please bend the cable and lead it downwards to prevent water or moisture from entering the instrument. Tighten the cable sealing sleeve.
- Stirring effects: If there is stirring in the tank, the integrated ultrasonic level transmitter should be away from the stirrer to eliminate the false echo effect caused by the stirring blades. If foam is generated due to stirring or waves are turned up, use the guide wave tube installation method.
- Foam effects: During feeding, stirring, or other treatments in the container, foam can form on the surface of some media, causing the ultrasonic level transmitter signal to attenuate. To avoid measurement errors caused by foam, install the sensor in the guide tube or use a guided wave radar level gauge. The guided wave radar level gauge is not affected by foam and is an ideal choice for this type of application.
- Airflow effects: If there is a strong airflow or air vortex in the container, or it is installed outdoors and the wind is strong, install the sensor in the guide tube or use a guided wave radar level gauge.
Ultrasonic Level Transmitter Installation method:
In open environments, installation is generally achieved using a bracket, securing the device with the included locknut. Alternatively, you can drill a circular hole with a diameter of 60mm at the desired installation spot on the top of the tank or lid, and place the device in it. Then, tighten the locknut from underneath.
It is crucial to ensure that the face of the transmitter’s probe is parallel to the liquid surface being measured.
As illustrated, the probe of the device emits waves that reflect back upon hitting the liquid level. The probe calculates the time taken from emission to reception of these waves to determine the measured empty distance, H.
Subtracting the measured empty distance H from the installed height TH gives you the current liquid level, L. The transmitter’s range is the distance it can measure, and the installed height TH should be less than this range.
The device’s blind zone is the area near the probe that cannot be measured. The distance between the highest liquid level and the probe should be greater than the blind zone. For instance, if the blind zone is 0.5m, the distance between the highest liquid level and the probe must be more than 0.5m.
For example: If the range is 6 meters, the blind zone is 0.45 meters, the actual maximum measurable liquid level is between 0 to 5.5 meters. The emission of waves from the probe is a diffusion process, meaning it has a directional angle. Pay attention during installation to avoid hitting protrusions on the pool wall or the edge of the channel.
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Ultrasonic Level Transmitter is a widely used level meter. When installing, pay attention to meet the installation requirements, including the environmental requirements of the site, avoiding the facilities in the tank, ensuring that the highest material level does not enter the measurement blind area, and the requirements of the installation location.
When installing an ultrasonic level gauge, installation principles must also be considered. The emitting surface of the probe should be kept parallel to the liquid surface, and the installation position of the probe should avoid the position where the liquid level fluctuates violently, etc.
Sino-Inst is a professional supplier of Ultrasonic Level Transmitter. Our Ultrasonic Level Transmitter is exported to various countries around the world. If you have any questions about Ultrasonic Level Transmitter Installation, please feel free to contact our Sino-Inst technical engineers.
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Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.
Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.