A Measurement Assurance Program (MAP) using sonic nozzles

Ford Motor Company is involved in accurately measuring the air flow to internal combustion engines. In this endeavor, Ford has constructed many different flow test stands and, to be assured that each test stand is measuring the air mass flow rate correctly, a Measurement Assurance Program (MAP) has been implemented. This paper describes the physical hardware (artifact) which consists of piping sections and three sonic nozzles. It presents the methodology of obtaining calibration data on two tandem sonic nozzles (installed in series) and how to combine the results for the three sonic nozzles for test stand evaluation. The MAP artifact can also be used for inter-laboratory comparison. Flow calibration data from two nationally known flow laboratories (NIST and CEESI) is presented. The data is presented in the traditional form of throat Reynolds.