Sinica Treebank: Design Criteria, Representational Issues and Implementation

The disclosed apparatus measures the mass rate of flow of gas through an orifice of a flow nozzle under critical flow conditions and comprises a reservoir having an inlet connected to a source of high pressure through a first valve and an outlet connected to a flow nozzle adapted to conduct pressurized gas from said reservoir under critical flow conditions to a region of low pressure downstream of the flow nozzle. The critical flow conditions are established by a second valve mounted downstream of the nozzle orifice. Density and pressure measuring devices are coupled to the reservoir and provide signals representative of the density and pressure, respectively, of the gas flowing through the flow nozzle. The density and pressure signals are applied to a device which calculates the square root of the product of density and pressure to provide a signal proportional to the mass rate of gas flow.