Operation principle of Venturi nozzle: If the pressure ratio in front of and behind the nozzle exceeds critical level, gas flow in the throat is accelerated to critical speed (it is equal to local speed of sound). Mass flow is the largest possible flow under stated conditions (pressure, temperature) of gas in the nozzle inlet. Production of critical nozzles complies with particular ventilation standard. Calculation of critical nozzles is ensured by our own authorised software.

Use: only for gases; as testing meter for serial production of energy equipment