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Generally speaking, the output signal (frequency) of the vortex flow meter vortex flow sensor is not affected by the change of fluid physical properties and composition, which means that the meter coefficient is only related to the shape and size of the vortex generator and the Reynolds number.

 

The advantages are: simple and firm structure, convenient installation and maintenance; applicable to a variety of fluids, including liquid, gas, steam and some mixed phases; higher accuracy, generally up to ±1%R; wide flow range, up to 10:1 Or 20:1 or greater; small head loss; no zero drift; relatively cheap;

 

Disadvantages are: not suitable for low Reynolds number Re<20,000, and there are restrictions on the use of high viscosity, low flow rate, and small diameter; the environment has higher requirements, and places with vibration should be avoided as much as possible, and the upstream needs longer Straight pipe section; the meter coefficient is lower, the larger the caliber, the lower. The signal resolution is reduced, so the aperture should not be too large, generally used in DN15~DN300mm.

 

1. Advantages

The vortex flowmeter has a simple and firm structure, and is easy to install and maintain (compared with a throttling differential pressure flowmeter, it does not require a pressure guiding tube and a three-valve group to reduce leakage, blockage, freezing, etc.).

 

There are many types of applicable fluids, such as liquids, gases, vapors and some mixed-phase fluids.

 

The accuracy is high (compared with differential pressure type and float type flowmeter), generally the pressure loss of the measured value (±1%～±2%) is small (about 1/4～1/2 of orifice flowmeter). The output pulse signal proportional to the flow rate is suitable for total measurement without zero drift; within a certain Reynolds number range, the output frequency signal is not affected by fluid physical properties (density, viscosity) and composition, that is, the meter coefficient is only related to the vortex The shape and size of the generating body and the pipeline are related, and it only needs to be verified in a typical medium and is suitable for various media.

 

 

So what are the limitations of vortex flowmeters?

 

2. Limitations

The vortex flowmeter is not suitable for low Reynolds number measurement (ReD≥2×104), so its application is restricted under the conditions of high viscosity, low flow rate and small diameter.

The stability of the vortex separation is affected by the distortion of the flow velocity distribution and the swirling flow. It is necessary to configure a long enough straight pipe section or install a flow regulator (rectifier) ​​according to the different forms of upstream obstructions. Generally, throttling differential pressure flowmeters can be used for reference. The length of the straight pipe section requires installation. Compared with turbine flowmeters, the meter coefficient is lower, the resolution is low, and the larger the caliber, the lower it is. Generally, full-tube flowmeters are used below DN300. The instrument still lacks theoretical research and practical experience in pulsating flow and mixed phase flow.