Patent ID: 7412902
Filing Date: 2008-08-19
Classification: G01F,G01N

Abstract:
1. A clamp-on flowmeter for determining and/or monitoring the volume and/or mass flow rate of a medium in a pipe, comprising: two ultrasonic transducers, which emit receive ultrasonic measuring signals; coupling elements associated with each of said ultrasonic transducers, via which the ultrasonic measuring signals are coupled into, and out of, the pipe at a predetermined in-coupling and out-coupling angle; and a control/evaluation unit, which determines the volume and/or mass flow rate of the medium flowing in the pipe on the basis of the travel-time difference principle; wherein: said coupling element includes at least two element portions, which are embodied and/or arranged in such a manner that the influence of temperature changes on a predetermined in-coupling angle (ζ) into the containment and/or on a predetermined out-coupling angle (ζ) out of the containment is approximately compensated in a predetermined, or extended, temperature range, and said at least two element portions comprise coupling wedges or lead-in members, the dimensions of said at least two element portions, or the path lengths, which the ultrasonic measuring signals travel in said coupling wedges or said lead-in members, are so selected that the sum of the corresponding travel times, which the ultrasonic measuring signals require for passing through said coupling wedges or said lead-in members, is at least approximately constant over a predetermined temperature range.