Common problems and solutions for vortex flowmeters

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When the flow meter is installed on a pipe, the X-axis must be aligned with the pipe, but the Y-axis of the flow meter (together with the Z-axis) can be rotated freely around the X-axis to any orientation. Understanding this, we have our first measure: observe or determine the main vibration direction of the short channel, then rotate the flow meter until the Z-axis aligns in the opposite direction to this main vibration, and fix the instrument to operate in that orientation. Whether a vortex flow meter is suitable depends on the Re calculation results. Generally speaking, for media with high viscosity, if the pipe diameter is large and the flow rate is not too low, the feasibility of using a vortex flow meter increases. I. Adjust the installation position of the flow meter. The vibration resistance of flowmeters in different directions varies. The orientation of the flow meter installed on the pipeline can be represented by X-Y-Z three-dimensional coordinates, where X refers to the direction of the pipeline’s centerline, that is, the direction from the inlet to the outlet of the flow meter ； Z is the axial direction of the flowmeter cylinder ； Y is the direction perpendicular to the pipeline centerline as well as perpendicular to the axial direction of the flowmeter cylinder; it is also the direction in which the transverse force of the vortex street acts. The flow meter has the strongest vibration resistance in the Z direction and the weakest in the Y direction (readers are invited to think: why?) ). When the flow meter is installed on a pipe, the X-axis must be aligned with the pipe, but the Y-axis of the flow meter (together with the Z-axis) can be rotated freely around the X-axis to any orientation. Understanding this, we have our first measure: observe or determine the main vibration direction of the short channel, then rotate the flow meter until the Z-axis aligns in the opposite direction to this main vibration, and fix the instrument to operate in that orientation. II. Add pipe fixing brackets to limit the pipe amplitude. Installing a fixed support downstream of the flow meter, right next to it, can reduce the amplitude of pipe vibrations; in some cases, it can also increase the resonance frequency of the piping system (which helps the instrument’s circuitry to perform noise reduction), thereby reducing vibration noise. III. When using a vortex flow meter to measure gases or steam, it is necessary to measure both the pressure and temperature of the medium simultaneously. What are the requirements for the locations of pressure and temperature measurement points? The pressure and temperature measurement points should be installed at the locations specified by the vortex flowmeter manufacturer in the installation and operation instructions. The temperature measurement point should be located 3–5D behind the flow meter; if it is too close to the flow meter, the thermometer probe can affect the quality of the signals from the flow meter. If the temperature measurement point is too far away from the flow meter, the temperature measured may differ from the temperature at the flow meter itself. The pressure measurement points must be installed exactly at the locations specified by the manufacturer; otherwise, additional measurement errors will occur. Due to the pressure difference before and after the flow meter, the pressures on either side of it are different, and thus the density of the fluid also varies. IV. What should be considered when using vortex flowmeters for high-viscosity media? Vortex flowmeters are not suitable for high-viscosity media. Here, “high viscosity” refers to high kinematic viscosity. For liquids, the dynamic viscosity should be below 50 cst (it is only 1 cst at room temperature). Thick liquids, such as heavy oil, have very high dynamic viscosity at room temperature; if a vortex flow meter is to be used, it must be heated to above 120°C to reduce its dynamic viscosity to below 10 cst. For gases, the dynamic viscosity should be below 50 cst (15 cst for air at normal temperature and pressure). Gases with low density generally have a higher dynamic viscosity; for example, hydrogen at normal pressure can have a dynamic viscosity as high as 90 cst. When using a vortex flow meter to measure hydrogen flow, it is better to have a higher pressure for hydrogen, as the dynamic viscosity of hydrogen is much lower at high pressures. When using vortex flowmeters for high-viscosity media, it is necessary to carefully calculate the Reynolds number at the minimum flow rate; whether a vortex flowmeter can be used depends on this Reynolds number (Re≥2×104), rather than directly on the viscosity of the medium. The viscosity of the medium comes into play through the Reynolds number. Therefore, whether a vortex flow meter can be used also depends on the pipe diameter and flow rate (Re=Dv/v). Whether a vortex flow meter is suitable depends on the Re calculation results. Generally speaking, for media with high viscosity, if the pipe diameter is large and the flow rate is not too low, the feasibility of using a vortex flow meter increases. It’s purely my personal opinion; Haiyou, please add more