【2025 Flow Meters】Selection of Five Common Ultrasonic Flow Meters and Determination of Installation Locations
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This post was last edited by The one on 2025-12-24 06:29. An ultrasonic flow meter is mainly composed of several components, including an ultrasonic transmitter, an ultrasonic receiver, electronic circuits, a flow display unit, and an accumulation system. Among them, the ultrasonic generator is primarily used to generate ultrasonic waves and transmit them into the fluid; the ultrasonic receiver is mainly used to capture the ultrasonic waves that have passed through the fluid. Once captured, these ultrasonic waves are amplified and converted via electronic circuits, and the flow rate is transmitted in the form of electrical signals to the display screen where the result is shown; the accumulation system is responsible for calculating the cumulative flow rate.
1. Doppler ultrasonic flowmeters can only be used to measure fluids that contain an appropriate amount of particles or bubbles capable of reflecting ultrasonic signals, such as factory discharge fluids, untreated wastewater, and factory process fluids with stable impurity levels. It should be noted that it has relatively strict requirements for the medium being measured: it cannot be pure water, and the impurity content must remain relatively stable in order to enable proper measurement. Moreover, the performance of instruments from different manufacturers, as well as their requirements for the medium being measured, also vary. When selecting such ultrasonic flowmeters, it is necessary to have a good understanding of the medium being measured, as well as to possess in-depth knowledge of the performance and accuracy of the chosen ultrasonic flowmeter and its requirements regarding the medium in question.
2. Portable ultrasonic flowmeters are suitable for temporary measurements. They are primarily used to check the operation of other flow meters already installed in pipelines, to conduct fluid balance tests in a particular area, and to determine the flow rate in the pipelines at that time. When not used for fixed installation but for these purposes, choosing a portable ultrasonic flow meter is convenient and cost-effective.
3. Time-difference ultrasonic flowmeter: The type that is produced in the largest quantities and has the widest range of applications at present is the time-difference ultrasonic flowmeter. It is primarily used to measure the flow rate of clean liquids, and is widely applied in water supply companies and the industrial water sector. Furthermore, it can also measure the flow rate of homogeneous fluids with low impurity content (impurity level less than 10 g/L and particle size less than 1 mm), such as wastewater, with an accuracy of up to ±1.5%. Practical applications have shown that the use of time-difference ultrasonic flowmeters can achieve satisfactory measurement results for the corresponding fluids.
4. Tubular ultrasonic flowmeters offer the highest accuracy, reaching ±0.5%, and are not restricted by the material or lining of the pipeline; they are suitable for applications where high precision in flow measurement is required. However, as the pipe diameter increases, the cost also rises. Generally, it is more economical to use tube-type ultrasonic flowmeters with small to medium diameters.
5. Fixed ultrasonic flowmeters: If there is sufficient installation space, the use of insert-type transducers instead of surface-mounted transducers eliminates completely the impact of pipe lining, scaling, and pipe walls on the attenuation of ultrasonic signals. This results in higher measurement stability and also reduces maintenance efforts significantly. Furthermore, since plug-in transducers can also be installed without interrupting flow, their use is continuing to expand.
The measurement point for an ultrasonic flowmeter should be selected properly. 1. First, select pipes that are uniform and dense, as this facilitates ultrasonic transmission. The sensor for the ultrasonic flow meter should be installed in a section of the pipe where there is a uniform straight section along the flow path; moreover, the pipe must be filled with fluid at the time of installation. Select the pipe section in which the fluid fills the entire pipe, such as a vertical section (with fluid flowing upward) or a horizontal section. For pipes with openings or that are half-full, the flow meter should be installed at the U-shaped section. Avoid installing at the highest point of the piping system or on vertical pipes with a free outlet (where the fluid flows downward).
2. The installation location for the ultrasonic flowmeter sensor should be in a straight pipe section with a length of more than 10 times the diameter of the straight pipe upstream, and more than 5 times the diameter downstream, and such a section should contain no valves, elbows, diameter changes, or any other obstacles. The installation site must be sufficiently far away from interference sources such as valves, pumps, high-voltage electricity, and frequency converters. The installation location of the ultrasonic flowmeter sensor should avoid flanges, welds, and diameter changes.
3. Select a pipe section with a smooth and clean surface; if there is rust or similar, it must be removed by sanding before the sensor is installed. For pipes that are quite old, the issue of scale buildup on the inner wall of the pipe needs to be taken into account. When no such pipe section without defects can be found, the scale buildup must be treated as part of the lining in order to achieve better measurement accuracy.
4. The temperature and pressure at the installation location of the ultrasonic flow meter should be within the operating range of the sensor.
5. When installing external clamp-type or plug-in sensors, they should be positioned horizontally on the axis of the pipeline, at an angle of 45° relative to the horizontal axis. This prevents issues such as incomplete filling of the pipe, air bubbles, or sediment at the bottom from affecting the proper functioning of the sensors. If horizontal installation is not possible due to space constraints at the installation site, the sensor can be installed vertically or at an angle, provided that the pipeline is filled completely without any bubbles.