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Title: A Measurement Assurance Program Map() Using Critical Flow Venturis
Author: Richard W. Caron, Thomas m. Kegel, Charles L. Britton
Source: 1999 International Symposium on Fluid Flow Measurement
Year Published: 1999
Abstract: Ford Motor Company is involved in accurately measuring the air mass flow rate into their internal combustion engines for improved fuel economy and for meeting the required level of pollutant output. In this endeavor, Ford has constructed many different flow stands which measure air mass flow rates during various fabrication and manufacturing processes. To be assured that each flow stand is measuring the mass flow correctly, a Measurement Assurance Program (MAP) has been implemented. This paper describes the physical hardware (artifact) which consists of piping sections and three Critical Flow Venturis (CFV). It presents the methodology of obtaining calibration data on two CFVs (installed in series), and how to combine the results for the three CFVs to determine the accuracy of the measured air mass flow rate. The MAP artifact has been used for inter-laboratory comparison. Data from several internationally known flow laboratories is presented. Two laboratories (NIST and CEESI) have performed multiple calibrations on the artifact over a period of several years, while four other laboratories have performed a single calibration. The presented data shows the comparison between laboratories and estimates whether the differences are due to systematic or random effects by a Youden analysis.