Error analyses of filling control systems for liquid amount-given
It is of instructive significance to systematically analyze the factors that influence the precision of filling control systems for liquid amount-given. The sources of additional errors of volumetric flowmeter and Coriolis mass flowmeter were analyzed in the paper. The factors that influence the filling overshoot and lead to overshoot error were discussed in particular. Then the general system error was expressed and the main approaches to improving the filling precision were summarized. It is indicated that the filling precision of system is mainly decided by the precision of flowmeter and other instruments such as thermometer and manometer on condition that the valve is shut off in advance under low instantaneous flowrate. The influence of overshoot error on the filling precision of system is not remarkable.
The identification of external factors which influence the calibration of Coriolis massflow meters
Abstract It has been suggested that, by monitoring the sensor signals and the meter drive signal, it may be possible to create a Coriolis meter which can identify the presence of a variety of external disturbances and can give a warning and/or make a correction to the meter output in order to maintain accuracy. This paper presents the findings from an investigation of the response of commercially available Coriolis meters to such disturbances. The results of this program of tests are reported and the implications of these results on the practicality of the creation of an ‘intelligent’ meter are discussed.
Effect of pulsating flow on Coriolis mass flowmeters
Abstract The last ten years have seen an increasing use of Coriolis flowmeters in the measurement of small flows of liquids. The performance of Coriolis meters under pulsating flow conditions was not well known, however. This paper presents some investigations on such flowmeters in the presence of monofrequent and polyfrequent pulsating flows. The linearity of the flow characteristics is checked mathematically and the mechanical resonances of the measuring tubes are determined. Two U-tube type Coriolis meters are tested and the measuring error resulting from the pulsation of the flow is examined. The investigations are carried out with monofrequent pulsation by a special test rig flow and with geared and piston type pumps (polyfrequent excitation).