Critical / Sonic nozzles

Flow measurement elements with highest accuracy

EP Ehrler Prüftechnik manufactures sonic nozzles in the flow range from 0.005 up to 2000 m³/h. In addition to the standard range, EP Ehrler Prüftechnik offers customerspecific nozzles which are perfectly designed for your application in accordance to DIN EN ISO 9300*. Nozzle holders including sensor connections are available for all nozzle sizes for installation in customer applications

Several nozzles can be combined to set several volume flows, allowing a high number of different flow rates to be generated rapidly. It is possible to generate e.g. 28 = 256 different flow rates using 8 critical nozzles. Binary staggering of the nozzles ensures a uniform coverage of the volume flow range.

*) For flow rates less than 0.1 m³/h only based on DIN EN ISO 9300.

Technical data

Flow range0.005 up to 2000 m³/h*
Highest accuracyup to 0.12 % MV*
Recalibration periodup to 10 years for laval nozzles
Rapid reaction times steady flow within 500 msec
You can find exact data in the brochure EPE167590:

Application examples

  • Calibration of flow meters, e.g. gas meters, LFE, Venturi nozzles, MFM, MFC
  • Periodic calibration tasks, e.g. calibration device for production parts (valves, actuators, air mass meters, etc.)
  • Flow reference without further measurement technology


  • Single nozzles in the flow range from 0.005 to 2000 m³/h
  • Suitable nozzle holders with sensor connections
  • Nozzle wheel system for combining different nozzles
  • SMF® – SonicMasterFlow® nozzle test bench

SMF® – SonicMasterFlow® systems

SMF® – SonicMasterFlow® systems are complete nozzle test benches that operate with automatically controlled nozzle systems in drum, block or register design. These nozzle systems can also be purchased separately.

More information at: