Mass flow measurement
First Claim
1. A mass flow transducer comprising:
- a vibratable element mass flow sensor;
means for exciting said element into vibration;
means for determining the value of the phase difference in the vibration between first and second positions along the sensor;
means for determining an amplitude of the vibration;
means for correcting the phase difference value in dependence upon the amplitude, such that the corrected value is representative of mass flow; and
means for determining the amplitude ratio of the vibration occurring at the first and second positions, and wherein the correction is dependent upon the amplitude ratio.
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Accused Products
Abstract
A coriolis-type mass flow transducer comprises a straight tube 10 through which a fluid whose mass flow rate is to be measured is arranged to flow while the tube is set into transverse resonant vibration in its second overtone mode. Mass flow is determined by measuring the phase difference between the vibration at two points along the tube 10. Such a transducer exhibits an offset at zero flow, which can vary with time. These variations are minimized by minimizing the damping effects on the tube 10 of bellows 6, 7 used to connect tube 10 in a flow line, and then corrected by measuring the amplitude ratio of the vibrations at the two points, and correcting the initially-determined offset in dependence upon changes in this amplitude ratio.
29 Citations
5 Claims
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1. A mass flow transducer comprising:
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a vibratable element mass flow sensor; means for exciting said element into vibration; means for determining the value of the phase difference in the vibration between first and second positions along the sensor; means for determining an amplitude of the vibration; means for correcting the phase difference value in dependence upon the amplitude, such that the corrected value is representative of mass flow; and means for determining the amplitude ratio of the vibration occurring at the first and second positions, and wherein the correction is dependent upon the amplitude ratio. - View Dependent Claims (2, 3, 4, 5)
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Specification