Estimating the Error Component Associated with the Selection of a Gas Flow Model in Critical Nozzles

Resumo

A more accurate model has been developed for an ideal compressed gas flow in a critical nozzle used as a standard for volumetric flow rate. An error assessment is carried out for the inadequacy of the classical model of a critical nozzle that is applied to obtaining the actual value of the volumetric flow rate produced by a nozzle in operating conditions. It is shown that the error of model inadequacy must be considered to be in the upper bounds region of the effective measurement ranges of gas counters when calibrating them by means of volumetric flow rate standards on critical nozzles.