Flow Nozzles – Applications and Limitations

Flow nozzles are generally used in steam (vapor) at high pipeline velocities (over 100 feet per second) as well as in water and light slurry. They are selected for these applications because their rigidity makes them more stable at higher temperatures and velocities than orifices.

A special type of flow nozzle, the critical flow nozzle, is used to operate at critical (“choked” or “sonic”) flow for flow limiting or as a secondary flow standard, for example, in proving natural gas flow meters.

When a flow nozzle and a square-edge orifice are sized to create the same differential at the same flow rate, the pressure loss of both is approximately the same.