Blow-off nozzle

air

A "sonic nozzle" (also known as "Critical Flow Venturis" or "Critical Flow Nozzles") is a flow meter that can be used as a calibration standard for gas flow meters or any flow measurement device. By design, sonic nozzles are a constant volumetric flow meter. However, with the use of a regulated pressure supply, the sonic nozzle becomes a "state-of-the-art" mass flow meter. Considering both the divergent section design and the flow rate, sonic nozzles may operate with an exit pressure as high as 90% of the inlet pressure.