Method for measuring mass flow rate of airflow or steam

Application Number: 00108907
Application Date: 2000.05.19
Publication Number: 1274835
Publication Date: 2000.11.29
Priority Information: 1999/5/20 EP 99109896.3
International: G01F1/84
Applicant(s) Name: Endress + Hauser Flowtec AG
Inventor(s) Name: Roman Habery;Gehard Eckert
Patent Agency Code: 11038
Patent Agent: zheng xiuzhe
Abstract Method of measuring the mass flow rate of a gaseous or vaporous fluid. The accuracy of this method is comparable to that of the measurement of liquids. The fluid flows through at least one flow tube (4) of a mass flow sensor (1) 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 (16). A first and second vibration sensor (17, 18) are attached to the flow tube, deliver a first and a second sensor signal (x17, x18), and are positioned at a given distance from each other in the direction of flow. The flow tube (4) 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 (x17, x18) have a phase difference from which a signal qf 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(Tm) dependent on the current temperature Tm of the flow tube (4).