In recent years, ultrasonic flowmeters have been more and more widely used in flow measurement of various fluids, and they play a very important role in measurement management. In actual use, we found that inaccurate measurement is mostly caused by improper probe installation. Therefore, the correct installation of the probe becomes the number one problem. After long-term practice, we believe that the following are the principles that should be followed during the installation of the probe.1. Select the installation location of the probe1.1 Conditions that should be met by the installation location(1) There is no excessive dust and corrosive gas in the workplace; (2) Straight pipe length: more than 10D on the upstream side, and more than 5D on the downstream side (when the flow rate is low, the straight pipe requirements can be appropriately reduced): (3) upstream side There should be no disturbance factors (such as pumps, valves, etc.) within 30D; (4) The fluid must be filled with the pipeline, and it cannot contain bubbles or excessive impurities; (5) The pipe where the probe is installed should not have strong mechanical vibration; (6) The probe is installed Sufficient space is needed around the pipe.1.2 Points to note(1) For horizontal pipelines, the probe should be installed within ±45° of the horizontal centerline; (2) For vertical pipelines, the probe can be installed at any position on the outer circumference; (3) Avoid installing the probe in the pipeline Deformation parts, flanges or welding parts.2. Choose the installation method of the probe. The probe adopts the V method and the Z method for installation. The Z method is used in the following situations: (1) The installation space is limited; (2) The measured fluid contains a small amount of impurities; lining). The basis for selecting the installation method: Generally speaking, the Z method is used for the installation of D>300mm pipes.Third, the treatment of the probe mounting surfaceBefore installation, first remove the rust, dirt, etc. on the surface of the pipe (if there is a protective layer on the surface of the pipe, the protective layer should be stripped off), so that the surface of the pipe wall is smooth and free of dirt. The cleaning range should reach the entire circumference of the probe installation distance L+200mm width.Fourth, the determination of the installation pointStep 1: Make standard paper(1) Prepare a paper tape with a long side of 4D or more and a wide side of 200mm or equal to D. (2) Draw a wide-sided parallel line (also called a marking line) at a distance of 100mm from the long side of the tape.Step 2: Determine a point 100mm away from the edge of the treated pipe section, and align the edge of the marking line with this point. Roll up the standard paper close to the tube wall so that the marking line is parallel to the tube axis, and the edges of the standard paper should coincide.Step 3: Extend the marking line of the standard paper and draw a straight line on the pipe.Step 4: Draw a circular line on the pipe along the standard paper, and the intersection with the straight line A is A0.Step 5: Use the V method to install, remove the standard paper, draw the line segment A0A2=L (L is the probe installation distance) on the straight line, and determine the A2 point. A0 and A2 are the probe installation points.For example: L=200mm Step 6: Use Z method to install, draw a circle line on the pipe along the other side of the standard paper, and cross the straight line at A1. Starting from the straight line A0A1, the standard paper moves along the circle. At the 1/2 circle, extend the marking line on the standard paper, draw a straight line on the pipe, and intersect with the two circle lines on the pipe. The intersection point is B1B2.Remove the standard paper, draw the line segment B1B2 (L is the probe installation distance) on the self-line, and determine the point B2. A0 and B2 are the probe installation points.Five, install the probe on the pipeline1) Polish the installation point, the polishing area is about 3 times the area of the probe; 2) Remove the oil on the probe emitting surface and the pipe installation surface; 3) Apply the couplant to the entire emitting surface of the probe without forming air bubbles; 4) In the pipe Coat the surface with silicone grease; 5) Stick the probe firmly on the pipe wall, and fix the probe with cloth or steel tape (note: the emission directions of the two probes must be opposite).
Post time: 21-09-21