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.
Factors which influence the variability of turbine flowmeter signal characteristics
Abstract There have been suggestions that the detailed characteristics of the signals from turbine flowmeters can be used to derive information about both the `health' of the meter and features of the flow through it. To assess the feasibility of such suggestions, information is needed on the variability of signal characteristics obtained from meters in nominally identical flows. This paper reports data obtained during tests performed at the National Engineering Laboratory (East Kilbride, Glasgow). The majority of the tests involved a 100 mm diameter turbine meter installed in the oil flow calibration facility but data were also collected for different diameter meters and different fluids. A significant component of the signal characteristic is shown to depend on physical features of the turbine blades and to be representable as an array of `blade spacing unevenness'. The variability associated with estimates of this parameter is established and the possibility that changes in the parameter can be correlated with changes in meter calibration is examined. The variability of other parts of the signal characteristic with changes in flow conditions both upstream and downstream of the meter is examined.