SINN MESSTECHNIK calibrates critically operated Venturi nozzles primarily for manufacturers and users of gas meter test benches worldwide. The used measurement technique is consistent with the state of the art. Regular comparison measurements and round robin tests (among others with the PTB in Braunschweig) create confidence with regard to the documented measurement results. This is particularly important if the nozzles are used for calibration of gas meters. However, an orientation towards the future use does not take place on the part of the laboratory. All calibrations are performed with the greatest possible care and with demand for flawless execution. Annual audits and monitoring visits (conducted by experts of the PTB and by external auditors) provide additional reliability. In addition, SINN MESSTECHNIK is a member of the Technical Committee for Flow Measurands of the German Calibration Service (DKD) under the auspices of the Physikalisch-Technische Bundesanstalt (PTB).