Abstract: A method of determining flow parameters of a streaming gas in a conduit for medical applications. Longitudinal waves are generated in a transmitter connected from outside to a conduit. These waves are transmitted along two diagonal paths through the streaming medium in an upstream and a downstream direction, and received by two receivers which are located in a diagonal upstream and downstream position and on an opposite side relative to the transmitter, also connected to the conduit. A transit time value of the waves between the transmitter and each of the receivers is determined. A difference value on the basis of the determined transit time values is generated and the flow parameters are determined on the basis of the difference value. This measuring method is highly independent of the propagation velocity of the wave in the medium streaming in the conduit therefore also independent of the temperature and humidity of a gaseous medium.

Abstract: According to the method longitudinal waves are generated in a transducer used only as a transmitter connected from outside to a conduit. These waves are transmitted along two diagonal paths through the streaming medium in an upstream and a downstream direction, and received by two transducers used only as receivers which are located in a diagonal upstream and downstream position and on an opposite side relative to the transducer used as a transmitter, also connected to the conduit. A transit time value of the waves between the transducer used as a transmitter and each of the transducers used as receivers is determined. A difference value on the basis of the determined transit time values is generated and the flow parameters are determined on the basis of said difference value. This measuring method is highly independent of the propagation velocity of the wave in the medium streaming in the conduit therefore also independent of the temperature and humidity of a gaseous medium.