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Blow-Down Calibration of a Large Ultrasonic Flow Meter



Aaron Johnson, Eric Harman, Joey Boyd


Oil and gas production industries use large (diameter > 0.8 m) ultrasonic flow meters (USMs) to measure exhaust gas from flare stacks, emissions from smokestacks, flow of natural gas, etc. Since most flow laboratories do not have compressors with sufficient flow capacity ( > 10 kg/s) to calibrate large flow meters, calibrations are performed using the blow-down method where flow is generated by discharging high pressure tanks, leading to significant flow transients. We used an array of critical flow venturis (CFVs) in a blow-down facility to calibrate a large (D = 89.5 cm) 8-path ultrasonic flow meter. The flow transients associated with the blow-down process caused large spatial and temporal variations in temperature that dominated (40 % to 67 %) the uncertainty budget. Our uncertainty analysis accounts for transient-generated uncertainties and provides guidelines for improving blow-down calibrations of large flow meters.
Flow Measurement and Instrumentation


Blow-Down Calibration, Large Ultrasonic Flow Meter, Transient Flow Calibration, Critical Flow Venturis


Johnson, A. , Harman, E. and Boyd, J. (2021), Blow-Down Calibration of a Large Ultrasonic Flow Meter, Flow Measurement and Instrumentation, [online], (Accessed May 29, 2024)


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Created April 21, 2021, Updated March 6, 2023