Limitations of turbine flowmeters in use

Although the turbine flowmeter has high viscosity, is suitable for high-pressure measurement, does not need to open holes on the meter body, is easy to make into a high-pressure meter, has good repeatability, and the short-term repeatability can reach 0.05%-0.2%. It is precisely because of its good repeatability, such as frequent calibration or high online calibration accuracy, that it is the preferred flowmeter in trade settlement. However, there are still limitations in the use process:

(1) Although turbine flowmeters are available in high viscosity types, ordinary types are not suitable for media with higher viscosity. As the viscosity of the medium increases, the flowmeter's measurement lower limit increases, the range decreases, and the linearity deteriorates.

(2) Fluid properties (density, viscosity) have a great influence on flow characteristics. Gas turbine flowmeters are easily affected by density, while liquid flowmeters are sensitive to changes in viscosity. Density and viscosity are closely related to temperature and pressure, and fluctuations in field temperature and pressure are difficult to avoid. Compensatory (corrective) measures must be taken according to the degree of impact on accuracy in order to maintain measurement accuracy.

(3) The instrument is greatly affected by the flow velocity distribution distortion and rotational flow, and the straight pipe section required upstream and downstream of the sensor is relatively long. If the installation space is limited, a flow conditioner (rectifier) ​​can be installed to shorten the length of the straight pipe section.

(4) The cleanliness requirements for the measured medium are high, which limits its application area. Although filters can be installed to remove dirty media, it also brings side effects such as increased pressure loss and increased maintenance.

(5) Calibration characteristics cannot be maintained for a long time and need to be calibrated regularly. For non-lubricating liquids, liquids containing suspended matter or abrasive liquids, bearing wear and jamming problems are more prominent, limiting the scope of use. After using carbide shafts and bearings, the situation is greatly improved compared to graphite bearings. For trade storage and transportation with high-precision measurement requirements, on-site calibration equipment is equipped, and regular calibration can be performed to maintain its characteristics.