Ultrasonic flowmeter installation is relatively simple and convenient compared to other types of flowmeters. Simply select a suitable measurement point by manually inputting the corresponding pipe parameters of the measurement point into the flowmeter, and then fixing the probe to the probe. It will do on the pipeline. The two sensors of the ultrasonic flowmeter must be installed in the horizontal direction of the pipe shaft surface and installed within ±45o of the horizontal position of the axis to prevent the upper part from being filled with tubes, air bubbles or sedimentation in the lower part, which may affect the normal measurement of the sensor. If it is not possible to install horizontally symmetrically due to the space of the installation site, the sensor can be installed vertically or at an angle of inclination under the condition that there is no air bubble in the upper part of the pipe. Before installing the probe, select the dense part of the pipe for probe installation. The area outside the tube where the probe is to be installed is cleaned, and all the rust paint is removed. It is better to clean the dirt and coating on the outer surface with a sanding machine, then wipe off the oil and dust with a clean cloth, acetone or alcohol, and then in the probe. The central portion and the wall of the tube are coated with sufficient coupling agent.
Ultrasonic flowmeter installation requires that during the probe process, there should be no air bubbles and gravel between the probe and the pipe wall. On the horizontal pipe section, install the probe on the horizontal axis of the pipe section to prevent air bubbles from being present in the upper part of the pipe. If the probe is not installed horizontally symmetrically, the probe can be mounted vertically or at an angled angle to ensure that there is no air bubble in the upper part of the tube.
The probe spacing is based on the inner distance edge of the two probes. After inputting the required parameters, the number displayed in the display window 25 is viewed, and the pitch of the probe is matched with the data of the window No. 25.
There are four types of probe installation methods. These four methods are v method, z method, n method and w method, respectively. The following are explained separately. Generally, in the case of small pipe diameter (dn15~200mm), the v method can be selected first; if the v method cannot measure the signal or the signal quality is poor, the z method is used. When the pipe diameter is above dn200mm or when measuring the cast iron pipe, the z method should be preferred.
Under normal circumstances, it is a standard installation method, which is easy to use and accurate. The measurable diameter ranges from 15mm to approximately 400mm; when installing the probe, note that the two probes are horizontally aligned with the centerline and the axis of the pipe.
When the pipeline is very thick or due to the presence of suspended solids in the liquid, the fouling of the inner wall of the pipe is too thick or the lining is too thick, the installation signal of the v method is weak, and when the machine is not working properly, the z method is used for installation. The reason is that when using the z method, the ultrasonic waves are transmitted directly in the pipeline without refraction (called single-sound path), and the signal attenuation is small. The z method can measure the pipe diameter from 100mm to 6000mm. When actually installing the flowmeter, it is recommended to use the z method for the pipeline above 200mm (the measured signal is larger).
When installed, the ultrasonic beam is refracted twice in the pipeline through the fluid three times (three sound paths), suitable for measuring small diameter pipes. The n method improves the measurement accuracy by extending the ultrasonic transmission distance (not commonly used).
Like the n method, the w method also improves the measurement accuracy of the small tube by extending the ultrasonic transmission distance. Suitable for measuring small tubes below 50mm. When the w method is used, the ultrasonic beam is refracted three times in the tube and passed through the fluid four times (four sound paths).
Checking the installation means checking that the probe is installed properly and that it is capable of receiving the correct, strong enough ultrasonic signal that will allow the machine to function properly to ensure long-term reliable operation of the machine. By checking the received signal strength, total transmission time, time difference, and transmission time ratio, it is determined whether the installation is better.
The quality of the installation is directly related to the accuracy of the flow value, and whether the ultrasonic flowmeter runs reliably for a long time. Although in most cases, the probe is simply applied with a coupling agent attached to the outside of the tube wall, the measurement results can be obtained. At this time, the following inspections are performed to ensure that the measurement results are good and the flowmeter is reliable for a long time. Running.
In general, the greater the signal strength, the more stable and reliable the measured value, and the longer it can operate reliably for a long time.
The signal quality referred to as the q value (shown in m90) refers to the degree of good or bad signal reception: the fv series uses a number from 00 to 99 to indicate the signal quality. 00 indicates that the signal is poor; 99 indicates that the signal is better, and generally requires more than 60.0.
Poor signal quality may be due to large interference, or poor probe installation, or the use of poor quality, non-dedicated signal cables. Under normal circumstances, the probe should be adjusted repeatedly to check if the coupling agent is sufficient until the signal quality is as large as possible.
The “total transmission time and time difference” displayed in the window can reflect whether the installation is suitable: because the measurement operation inside the flowmeter is based on these two parameters, when the “time difference” fluctuation is too large, the displayed flow rate and The flow rate will also jump sharply. This situation indicates that the signal quality is too poor, the pipeline condition may be poor, the probe is not properly installed, or the parameter input is incorrect.
Ultrasonic flowmeter installation requires transmission time ratio: When the transmission ratio exceeds 100±3, check whether the parameters (tube outer diameter, wall thickness, pipe, lining, etc.) are input correctly, and the installation distance of the probe is displayed in m25. The data is consistent, whether the probe is mounted on the same line of the pipe axis, whether there is too thick scale, whether the pipe at the installation point is elliptical or not.
The following four requirements are particularly noteworthy:
1) The input pipeline parameters must be correct and consistent with the actual conditions, otherwise the flowmeter may not work properly.
2) When installing, use enough coupling agent to stick the probe on the pipe wall, and check the signal strength and signal quality value displayed by the host, and slowly move the probe near the installation point until it receives a strong signal and is larger. Signal quality value. The larger the diameter of the pipe, the larger the range of movement of the probe. Then confirm whether the installation distance matches the installation distance of the probe given by m25, and whether the probe is mounted on the same line of the pipe axis. Pay special attention to the pipes that are rolled up by the steel plates because they are irregular. If the signal strength is always 0.00, the flowmeter does not receive the ultrasonic signal, check whether the parameters (including all parameters related to the pipeline) are entered correctly, whether the probe installation method is correct, whether the pipeline is too old, whether the liner is too thick, and the pipeline Is there fluid, too close to the valve elbow, too much air bubbles in the fluid, etc. If it is not for these reasons, you still can't receive the signal, so you have to try another measuring point, or use a plug-in sensor.
3) Confirm whether the flowmeter is working normally and reliably: the greater the signal strength and the higher the signal quality q value, the more reliable the flowmeter can work for a long time, and the higher the reliability of the displayed flow value. If the ambient electromagnetic interference is too large or the received signal is too low, the displayed flow value is less reliable, and the possibility of reliable operation for a long time is small.