The accurate measurement range of ultrasonic flowmeters
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For ultrasonic flowmeters used in trade measurement, the accuracy level can be required to be at ±0.5%, but what is the range for accurate measurement? Turbo flowmeters generally achieve the highest measurement accuracy within a flow rate range of 20%Qmax to Qmax, but I could not find this figure in the data sheet for the ultrasonic flowmeter (Elster-Instromet). Could XDJM, who is familiar with ultrasonic flowmeters, give some introduction? Thank you!
Working principles of ultrasonic flowmeters: time difference method (currently the most commonly used method); b. frequency difference method (acoustic ring method); c. phase difference method; d. Doppler method (currently the most commonly used method); e. correlation method; f. beam displacement method; g. vortex street method. The measurement range of gas flow velocity by ultrasonic flowmeters is: -30 to +30 meters/second. Turbine flowmeters achieve the highest measurement accuracy within the flow range of 20%Qmax to Qmax; the measurement error at low flow rates is mainly caused by bearing friction.
The range of accurate measurement should be determined by referring to the calibration specifications. Generally, for ultrasonic flowmeters, the accuracy level is within plus or minus 0.5% within the range of maximum flow rate and the critical flow rate; it is within plus or minus 1% below the critical flow rate. The maximum flow rate corresponds to a flow velocity of 30 m/s, while the critical flow rate corresponds to a flow velocity of 3 m/s. Make a judgment for yourself
I’ve learned that with the ultrasonic flowmeter here, along with chromatographic correction and comparison with upstream data, the error is around ±0.4%