摘要:
A method of determining a calibration or maintenance time interval after which a specific measurement device of a given type for measuring a quantity to be measured on a measurement site of an industrial site shall be re-calibrated or maintained is described, comprising the steps of: determining a criticality (C) of the specific device, based on the criticality (C) setting a reliability target (RT) for the device, wherein the reliability target (RT) denominates the probability of the device to be compliant according to a predefined criterion at the end of the calibration or maintenance time interval to be determined by this method, defining compliancy ranges for a measurable degree of compliance of the device, selecting a reliability model for a reliability of the device as a function of a normalized time interval (tn) and a set of at least one parameter (c1, . . . , cm) from a variety of predefined reliability models, determining a separate set of parameters for the selected reliability model for each of the compliancy ranges based on prescribed reliability expectation values (RV(tnpd)) for each of the error ranges, which a reliability function associated with this error range shall comply to at at least one predefined normalized time (tnpd), determining the degree of compliance of the specific measurement device and based on the degree of compliance determining the corresponding compliancy range, determining a normalized calibration or maintenance time (tn) as the time, at which a reliability function (R(tn)) given by the selected reliability model and the set of parameters determined for this compliancy range equals the reliability target (RT), and determining the next calibration or maintenance time interval based on a product of this normalized calibration or maintenance time (tn) and a given reference time interval (TR).
摘要:
A system for monitoring the leak-tightness of a tank, which is filled with a liquid with a lower density than water. The system has a liquid drain pipe, with a container that has a bottom, which is integrated horizontally in the liquid drain pipe with a damming element, which divides the container into a partial area on the supply flow side and partial area on the drain side. A first vibronic measuring device with a first vibrating unit protruding into the supply flow side partial area of the bottom determines whether the density of the medium undershoots a specified limit. A second vibronic measuring device with a second vibrating unit, at a position not exceeding the level of the first vibrating unit, which detects whether the vibrating unit are covered with medium, and with an evaluation unit uses the measured values of measuring devices to determine whether there is liquid from the tank in the container.
摘要:
A method of calibrating a measurement device, during which at least one given value of a quantity to be measured by the device is provided by a corresponding reference or standard. The indicated measurement indications and the corresponding given values of the measured quantity are recorded, at least one predefined characteristic property of at least one of the measurement indications is determined and compared to corresponding threshold range. Each threshold range was previously determined based on a statistically representative distribution of the values of the respective property determined based on measurement indications derived during execution of a statistically representative number of performances of measurements according to the respective operation procedure with measurement devices of the same type as the device under calibration. A potentially impaired measurement property of the device under calibration is indicated if at least one determined characteristic property exceeds the respective threshold.
摘要:
Monitoring structure and a monitoring method for monitoring at least one step of a process performed on an industrial site is described, which allows prompt, reliable and efficient detection of disturbances based on readily available information, provided by the measurement results of the measurement devices involved in the performance of the step, and determined based on a model of the step, comprising primary models for the measurement devices comprising a basic function representing a time dependency of the measurement results of the device, a first property determined by best fitting the basic function to the measurement results obtained by the respective measurement device, a secondary model for each of the primary models, each comprising a second property given by a dispersion of residues between the measurement results obtained by the respective measurement device and the corresponding fitted function, and tertiary models for those pairs of measurement devices, which render correlated measurement results during faultless performance of the respective step, each tertiary model comprising a third property, given by a degree of correlation between simultaneously obtained measurement results of the respective pair of measurement devices during performance of the respective step, and a reference range for each of the properties, comprising a range within which the respective property is expected to occur during faultless performance of the step.
摘要:
A method of determining a calibration or maintenance time interval, comprising the steps of: determining a criticality of the specific device, based on the criticality setting a reliability target for the device, wherein the reliability target denominates the probability of the device to be compliant according to a predefined criterion at the end of the calibration or maintenance time interval; defining compliancy ranges for a measurable degree of compliance of the device; selecting a reliability model for a reliability of the device as a function of a normalized time interval and a set of at least one parameter from a variety of predefined reliability models, determining a separate set of parameters for the selected reliability model for each of the compliancy ranges based on prescribed reliability expectation values for each of the error ranges, which a reliability function associated with this error range shall comply to at at least one predefined normalized time, determining the degree of compliance of the specific measurement device and based on the degree of compliance determining the corresponding compliancy range; determining a normalized calibration or maintenance time as the time, at which a reliability function given by the selected reliability model and the set of parameters determined for this compliancy range equals the reliability target; and determining the next calibration or maintenance time interval based on a product of this normalized calibration or maintenance time and a given reference time interval.
摘要:
A method of determining a calibration time interval for a calibration of a measurement device for measuring a quantity to be measured, which allows a safe optimization of calibration time intervals between consecutive calibrations. Performing a first calibration of the device at a first calibration time; adjusting, repairing or replacing the device and restarting the method from the beginning in case the first measurement error exceeds a predetermined error range including zero; performing a second calibration of the device at a second calibration time, adjusting, repairing or replacing the device and restarting the method from the beginning in case the second measurement error exceeds a maximum permissible error; determining the calibration time, at which a third calibration of the device shall be performed, and which is determined based on the first and the second measurement error, a probability density function for determining a measurement error of the device solely due to a calibration uncertainty inherent to the first calibration, a probability density function for determining a measurement error of the device solely due to a calibration uncertainty inherent to the second calibration, and the first and the second calibration time.
摘要:
A method of determining a calibration or maintenance time interval, comprising the steps of: determining a criticality of the specific device, based on the criticality setting a reliability target for the device, wherein the reliability target denominates the probability of the device to be compliant according to a predefined criterion at the end of the calibration or maintenance time interval; defining compliancy ranges for a measurable degree of compliance of the device; selecting a reliability model for a reliability of the device as a function of a normalized time interval and a set of at least one parameter from a variety of predefined reliability models, determining a separate set of parameters for the selected reliability model for each of the compliancy ranges based on prescribed reliability expectation values for each of the error ranges, which a reliability function associated with this error range shall comply to at at least one predefined normalized time, determining the degree of compliance of the specific measurement device and based on the degree of compliance determining the corresponding compliancy range; determining a normalized calibration or maintenance time as the time, at which a reliability function given by the selected reliability model and the set of parameters determined for this compliancy range equals the reliability target; and determining the next calibration or maintenance time interval based on a product of this normalized calibration or maintenance time and a given reference time interval.
摘要:
A system for monitoring the leak-tightness of a tank, which is filled with a liquid with a lower density than water. The system has a liquid drain pipe, with a container that has a bottom, which is integrated horizontally in the liquid drain pipe with a damming element, which divides the container into a partial area on the supply flow side and partial area on the drain side. A first vibronic measuring device with a first vibrating unit protruding into the supply flow side partial area of the bottom determines whether the density of the medium undershoots a specified limit. A second vibronic measuring device with a second vibrating unit, at a position not exceeding the level of the first vibrating unit, which detects whether the vibrating unit are covered with medium, and with an evaluation unit uses the measured values of measuring devices to determine whether there is liquid from the tank in the container.