Common malfunctions

Common Vortex Flowmeter Faults 9. A DN50 vortex flowmeter, as found in the instructions, has a flow rate range of 3-50m3/h. The result of calibration on the oil flow standard device is 10-50 m3/h, but the accuracy below 10m3/h is unqualified. How should this flowmeter be evaluated?

In the vortex flow juice specification, the indicated flow range is the flow range used for a specific reference medium, such as liquid—refers to normal-temperature water. When used with other media, the usable flow range will vary depending on the viscosity and density of the media. Because the oil flow standard device uses diesel oil with a viscosity greater than that of water and a density lower than that of water as a calibration medium, the lower limit flow rate of the flow meter will generally be increased, and the usable flow range will be narrowed. Therefore, it is normal for vortex flowmeters to calibrate on the oil flow calibration device to exhibit a small flow performance deterioration. From this it is not difficult to infer that if vortex flow juice is calibrated with liquefied petroleum gas (a low-viscosity medium), it will yield opposite results than water.

Flowmeter combination Flowmeter combination

1, vortex flowmeter measurement range is relatively large, generally 10:1, but the lower limit of measurement is limited by many factors: Re> 10000 is the most basic condition of vortex flowmeter work, in addition, it is also affected by the vortex The signal, which has a small vortex frequency f, also makes signal processing difficult. The upper limit of the measurement is the frequency response of the sensor and the frequency limit of the circuit. Therefore, the flow rate range must be calculated and calculated when designing, and the fluid flow rate should be selected. The use of on-site environmental conditions is complex. In addition to the environmental temperature, humidity, and atmosphere conditions, electromagnetic interference must be considered when selecting a model.

2, vibration is also a major rival of this type of instrument. Therefore, when using, care should be taken to avoid mechanical vibration, especially the transverse vibration of the pipe (the vibration of the axis of the vertical vortex generating body perpendicular to the axis of the pipe). This effect cannot be suppressed and eliminated in the structure design of the flowmeter. Since the vortex street signal is also sensitive to the influence of the flow field, the length of the straight pipe cannot be used to ensure the necessary flow conditions for the stable vortex street. Even a capacitive and ultrasonic type with strong vibration resistance ensures that the fluid is a fully developed unidirectional flow that cannot be ignored.

3, the media temperature has a great influence on the performance of the vortex flowmeter. For example, pressure-stressed vortex flowmeters cannot be used at 300°C for a long period of time because their insulation resistance will suddenly drop from 10-100MΩ at room temperature to 1-101Ω, and the output signal will also become smaller, leading to deterioration of the measurement characteristics. In the measurement system, the sensor and converter should be separated and installed so as to avoid long-term high temperature affecting the reliability and service life of the meter. Vortex flowmeter is a relatively new type of flowmeter and it is still in its development stage. It is not very mature, and if it is not properly selected, its performance cannot be well exerted. Only after a reasonable selection and correct installation, but also need to maintain regularly in the use of the process, and constantly accumulate experience to improve the predictability of the system failure and ability to judge, deal with the problem, so as to achieve satisfactory results.

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