Vibrating tube densimeter
AssigneeMicro Motion, Inc.
InventorsMarc Allan Buttler, Andrew Timothy Patten, Charles Paul Stack
Life of this patent
Estimating the term…
Abstract
A Coriolis effect densimeter which produces density output data of improved accuracy by embodying the principal that the natural frequency of a vibrating tube filled with material decreases with an increase in the material mass flow rate. High accuracy output data is achieved by measuring the density and the mass flow rate of material through the vibrating tube, correcting the measured density to compensate for the effect of the mass flow rate, and correcting the mass flow rate correction of the density measurement for changes due to temperature.
Claims30
A method of operating apparatus for ascertaining the density of material flowing through a flowmeter having vibrating tube means wherein a measured density of said flowing material changes as a flow rate of said flowing material through said vibrating tube means changes:
- said method comprising the steps of:
- measuring the period of vibration of said vibrating tube means as said material flows therethrough,
- generating a measured density value for said flowing material in response to said measurement of said vibration period,
- receiving a mass flow rate value representative of said mass flow rate of said flowing material through said vibrating tube,
- generating a flow rate effect factor defining the sensitivity of said measured density to changes in said mass flow rate of said flowing material;
- multiplying said flow rate effect factor by said measured mass flow rate to determine a mass flow rate induced density error value:
- and
- reducing said measured density value by an amount substantially equal to said mass flow rate induced density error value to determine said corrected density value;
- and
- transmitting said corrected density value to an output device.
A machine readable storage device, tangibly embodying instructions executable by a computer to perform method steps for ascertaining the density of material flowing through a flowmeter having vibrating tube means wherein a measured density of said flowing material changes as a flow rate of said flowing material through said vibrating tube means changes, said method steps comprising:
- measuring the period of vibration of said vibrating tube means as said material flows therethrough,
- generating a measured density value for said flowing material in response to said measurement of said vibration period,
- receiving a mass flow rate value representative of said mass flow rate of said flowing material through said vibrating tube,
- generating a flow rate effect factor defining the sensitivity of said measured density to changes in said mass flow rate of said flowing material;
- multiplying said flow rate effect factor by said measured mass flow rate to determine a mass flow rate induced density error value;
- reducing said measured density value by an amount substantially equal to said mass flow rate induced density error value to determine said corrected density value;
- and
- transmitting said corrected density value to an output device.
An apparatus for ascertaining the density of material flowing through a flowmeter having vibrating tube means wherein a measured density of said flowing material changes as a flow rate of said flowing material through said vibrating tube means changes, said apparatus comprising:
- means for measuring the period of vibration of said vibrating tube means as said material flows therethrough,
- means for generating a measured density value for said flowing material in response to said measurement of said vibration period,
- means for receiving a mass flow rate value representative of said mass flow rate of said flowing material through said vibrating tube,
- means for generating a flow rate effect factor defining the sensitivity of said measured density to changes in said mass flow rate of said flowing material;
- means for multiplying said flow rate effect factor by said measured mass flow rate to determine a mass flow rate induced density error value;
- means for reducing said measured density value by an amount substantially equal to said mass flow rate induced density error value to determine said corrected density value;
- and
- means for transmitting said corrected density value to an output device.
Dependencies are inferred from the claim text.