Vortex flow meter model selection
Vortex flow meter is a new type of flow meter which is successfully developed based on the principle of Carmen vortex street, because it has the advantages that other flow meter cannot have.
Flow measurement is a complex technology, and there are many types of flow meters. Even for a certain application, choosing a suitable flow meter will become a very technical task. It needs to be carefully and deeply before making the final choice. Consider and weigh many factors related to measurement issues. Vortex flow meter is a new type of flow meter which is successfully developed based on the principle of Carmen vortex street, because it has the advantages that other flow meter cannot have.
Key considerations in the selection and installation of vortex flow meter:
① Vortex flow meter is a speed type flow meter. The stability of vortex separation is affected by the flow velocity, so it has certain requirements for straight pipe sections, generally the first 10D and the last 5D;
② When measuring liquid, the upper limit flow velocity is limited by pressure loss and cavitation, which is generally 0.5 ～ 8m / s;
③ When measuring gas, the upper limit flow rate is limited by the compressibility change of the medium, the lower limit flow rate is limited by the Reynolds number and the sensor sensitivity, and the steam is 8 ~ 25m / s
④ Stress-type vortex flow meter are more sensitive to vibration, so when installing flow meter in pipelines with large vibrations, the pipelines must have certain vibration reduction measures;
⑤ Stress type vortex flow meter uses piezoelectric crystal as the detection sensor, so it is limited by temperature, generally -40 ～ + 300 ℃.
Vortex flow meter are susceptible to vibration interference. Well-designed vortex flow meter can eliminate interference through hardware and digital signal processing to obtain stable signals. A major problem in the installation of vortex flow meter is that long straight pipe sections are needed before and after. Some manufacturers can provide a design to reduce the diameter inside the flow meter, which greatly reduces the user's need for special vortex flow meter equipped with straight pipe sections.
Four main points for the selection of vortex flow meter:
1. As far as possible, do not use the flow meter to select the flow meter to work at the lower limit. Therefore, the caliber of the flow meter should be as small as possible to obtain a larger flow rate and flow range.
2. The flow meter should be used within the technical parameters of the working pressure and temperature range of the medium. Do not deliberately choose instruments with high pressure levels and ultra-high temperatures. Instruments should be selected based on actual working pressure and temperature, the latter being more expensive.
3. In explosion hazardous areas, explosion-proof flow meter should be used.
4. The lower limit flow of the vortex flow meter depends on the working condition density and kinematic viscosity of the medium, and its upper limit flow is generally not affected by the pressure and temperature of the medium. Therefore, determining the flow range only needs to determine the actual lower limit flow. After calculating the lower limit flow, check the flow range table to determine the corresponding caliber.