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Title: The Nova Meter Prover
Author: I.D. Williamson, B.D. Sawchuk, U. Karnik
Source: 1995 International Symposium on Fluid Flow Measurement
Year Published: 1995
Abstract: The NOVA natural gas meter prover consists of 24 identical sonic nozzles, one of which is diverted to a weigh tank to determine the mass flow rate for that nozzle. The total flow is the measured mass flow multiplied by the number of nozzles in operation. The on-line calibration of a single nozzle avoids the use of the critical flow factor, C*, thereby improving system uncertainty. Uncertainty calculations are presented which show that the uncertainty in the total mass flow rate is between 0.13% and 0.16%, depending on the number of nozzles in operation. Uncertainty of the nozzle bank alone is virtually independent of the number of nozzles open and is between 0.44% and 0.25% depending on how the uncertainty for C* is treated. Use of correlated variables to reduce the uncertainty is addressed. One nozzle from the meter prover was calibrated in air by CEESI. This C* was on average only 0.01% higher than the C* from the NOVA meter prover, with a standard deviation of 0 06% These results also indicate that C may be more accurate than previously thought, however more work is required in this area.