Coriolis-type flow meter and method for measuring the mass flow rate of a gaseous or vaporous fluid

Abstract

The accuracy of this method is comparable to that of the measurement of liquids. The fluid flows through at least one flow tube ( ) of a mass flow sensor ( ) of a Coriolis mass flow/density meter, which flow tube vibrates at a frequency f being equal to or in the vicinity of the instantaneous mechanical resonance frequency of the flow tube ( ) having a vibrator ( ). A first and second vibration sensor ( ) are attached to the flow tube, deliver a first and a second sensor signal (x , x ), and are positioned at a given distance from each other in the direction of flow. The flow tube ( ) is surrounded by a support frame or a support tube ( ) or held by a support plate so as to be capable of vibrating. The sensor signals (x , x ) have a phase difference from which a signal q is formed; it is multiplied by a function f(c) dependent on the speed of sound c in the fluid which can be approximated by a function f(T ) dependent on the current temperature T of the flow tube ( ).