Detailed explanation on the proper selection of the probe location for ultrasonic flowmeters

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When installing an ultrasonic flow meter, it is essential to determine the appropriate installation location; this helps to prevent problems during installation. If issues arise during the installation of the ultrasonic flow meter, it will be very difficult to deal with those problems. So everyone must be clear about what should be avoided when choosing the installation location. 　　1. Avoid installing the machine in locations such as water pumps, high-power radios, or frequency converters, where there are strong magnetic fields and vibration interference ； 　　2. The pipe sections selected should be uniform and dense, allowing easy transmission of ultrasonic waves ； 　　3. There must be a sufficiently long straight pipe section; the straight pipe section upstream of the installation point should be greater than 10D (note: D = diameter), and that downstream should be greater than 5D ； 　　4. There should be a distance of 30D between the installation point and the water pump upstream ； 　　5. The pipeline should be filled with fluid. 　　The installation requirements for ultrasonic flowmeters are the simplest and most convenient among all types of flowmeter installations: one only needs to select an appropriate measurement point, enter the pipeline parameters at that point into the flowmeter, and then fix the probe to the pipeline. 　　The two sensors must be installed horizontally in the plane of the pipe axis, within an angle range of ±45° from the axis level, to prevent issues such as incomplete filling in the upper part, air bubbles, or sediment in the lower part from affecting the accurate measurement by the sensors. If horizontal symmetrical installation is not possible due to space constraints at the installation site, the sensor can be installed vertically or at an angle, as long as there are no bubbles in the upper part of the pipe. Before installing the probe, select a dense section of the pipe for installation; clean the area outside the pipe where the probe will be placed, removing all rust and paint. It is advisable to use a grinder to smooth the surface, and then wipe away any oil or dust with a clean cloth dipped in acetone or alcohol. Finally, apply an adequate amount of coupling agent to both the center of the probe and the pipe wall. When installing an ultrasonic flow meter, it is crucial to ensure that there are no air bubbles or debris between the probe and the pipe wall. On horizontal pipe sections, the probe should be installed on the horizontal axis of the pipe cross-section to prevent the presence of bubbles in the upper part of the pipe. If it is not possible to install the probe in a horizontally symmetrical manner due to space constraints at the installation location, the probe can be installed vertically or at an angle, as long as there are no bubbles in the upper part of the pipe. 　　The probe spacing is determined based on the closest distance between the two probes. After entering the required parameters, check the figure displayed in window 25 and adjust the probe spacing to match the value shown in that window. 　　There are four ways to install the probe. These four methods are the v-method, z-method, n-method, and w-method respectively. The following explains each one separately. Generally, for small pipe diameters (dn15~200mm), the V method can be chosen first ； When no signal is detected or the signal quality is poor using the v method, the z method should be used; the z method is preferred when the pipe diameter is 200 mm or more, or when measuring cast iron pipes. Under normal circumstances, it is the standard installation method, which is easy to use and provides accurate measurements. The measurable pipe diameter range is from 15 mm to approximately 400 mm ； When installing the probes, make sure the two probes are aligned horizontally, with their center lines being horizontal to the pipeline axis. 　　When the pipe is very large, or when the presence of suspended particles in the liquid, excessive scaling on the inner wall of the pipe, or a thick lining results in a weak signal during installation using the V method and prevents the machine from functioning properly, it is necessary to use the Z method for installation. The reason is ； When the z-method is used, ultrasonic waves travel directly through the pipe without refraction (referred to as a single path), resulting in minimal signal attenuation. The diameter range that can be measured with the Z-method is from 100 mm to 6000 mm. When actually installing flow meters, it is recommended to use the Z method for pipes with a diameter of 200 mm or more (this yields the highest signal strength). 　　During installation, the ultrasonic beam refracts twice within the pipe and passes through the fluid three times (three acoustic paths), making it suitable for measuring pipes with small diameters. The n-method improves measurement accuracy by extending the ultrasonic transmission distance (an infrequently used method). 　　Similar to the n-method, the w-method also improves the measurement accuracy of small tubes by extending the ultrasonic transmission distance. Suitable for measuring small tubes under 50mm. When using the w-method, the ultrasonic beam is refracted three times inside the tube and passes through the fluid four times (four acoustic paths). 　　Checking the installation involves verifying that the probe is installed properly and that it can receive correct, strong enough ultrasonic signals to enable the machine to function properly, thereby ensuring its reliable operation over a long period of time. By checking the received signal strength, total transmission time, time difference, and transmission time ratio, it is possible to determine whether the installation is optimal. 　　The quality of the installation is directly related to the accuracy of the flow rate values and to the reliable operation of the flow meter over time. Although in most cases, simply applying a coupling agent to the probe and attaching it to the outside of the pipe wall will yield measurement results, the following checks should still be carried out to ensure the best measurement outcomes and the long-term reliable operation of the flow meter.