Last month, an old customer in Shandong purchased our company's eight clamped ultrasonic flowmeters. On the morning of Wednesday morning, the customer called and reflected a problem: The external clamp-type ultrasonic flowmeter installed on their new pipeline had accurate readings and the measurement was stable, but the readings were unstable on other seven old pipelines, sometimes even no signal. Stainless Welded Pipe,Stainless Steel Welded Pipe,201 Stainless Welded Pipe,304 Stainless Welded Pipe Shandong Fengmai Metal Materials Co., Ltd. , https://www.gghlw.com
On the phone, I asked the customer: “What is your pipe material?†(Of course I had already asked them when I first purchased, I would like to reconfirm it now to analyze the cause of the problem accurately.) He replied: “Carbon steel.†I Said: "Carbon steel is the most common material for pipelines, and it is also best for ultrasonic flowmeters. This is certainly not a problem." Then asked the media in the pipeline. He said it was sewage, which is also very common, and I ruled out . Next, the parameters such as temperature, flow rate, and whether or not the tube was fully filled were all eliminated. The bigger my doubts are at the end, what exactly is going on?
I really can't find a reason for it. I had to wait for him to wait. I'll consult our senior engineer Tang Gong first. After reporting the customer's situation to Tang, Tang also frowned a little, because each of our external-clip ultrasonic flowmeters was calibrated before delivery and had a one-to-one identity code to ensure that there were no quality problems. The customer's site is in full compliance with all conditions for the use of an external clamp type ultrasonic flow meter. After a bit of thinking, Tang Gong said with certainty that the problem lies in their pipeline and medium. I do not understand, Tang also explained in detail: The new pipeline can be used to illustrate that our flow meter is no problem, the old pipeline readings are not allowed and unstable, indicating that the pipeline wall has serious fouling, resulting in a weak ultrasonic signal, plus On the upstream of the customer's pipeline, no filter or grille was used, and there was a large block of dirt in the sewage, which hindered the transmission and reception of ultrasonic waves.
I also called the customer to ask for confirmation. Sure enough, their sewage conditions were rather poor. They did have large blocks and they were old pipes. They had been in constant use. They were indeed serious fouling of the pipe wall, and there was no filtration device upstream. I also told the client how to deal with it by following the instructions of Tang Gong:
1. Install filtering devices such as grilles upstream of the pipeline;
2. If it is inconvenient to stop the installation of the filter device, you can use a thick wooden stick to hit the position of the ultrasonic probe on the pipe to knock down the fouling of the inner wall of the pipe, which will facilitate the transmission and reception of ultrasonic signals.
Yesterday, customers returned feedback. They processed according to the second plan. Now the effect is not bad. Let's use it again.
Of course, the reasons for inaccurate reading of ultrasonic flowmeters are as follows: Several common ones are listed below for your reference and solutions to practical problems.
1. Ultrasonic Flowmeter Sensors The sediments placed on the top and bottom of horizontal pipes interfere with ultrasonic signals. Solution: Install the sensor on both sides of the pipe.
2. The ultrasonic flowmeter sensor is mounted on the water flow down pipe, and the pipe is not filled with fluid. Solution: Install the sensor on a fluid-filled pipe section.
3. There are devices that cause strong fluctuations in the flow regime, such as venturis, orifice plates, vortex streets, turbines, or partially closed valves, which are inaccurate in readings within the range of the transmitter's emission and reception. Solution: The sensor is mounted away from the device, upstream from the device 30D, downstream from the device 10D or upstream of the device.
4. The input diameter of the ultrasonic flowmeter does not match the internal diameter of the pipe. Solution: Modify the pipe diameter to match it.
August 31, 2024