Method for calibration in level measurement

摘要

Measuring the level of a material in a container using a sensor fitted above the highest level occurring and measuring the distance to the surface of the material in the container. An evaluation circuit computes the level from the distance measured by the sensor and the empty distance. The material volume is determined from the relationship between level and material volume memorized in the evaluation circuit. For calibrating a sensor in the case of an unknown empty distance, without having to completely empty the container, the on-going filling or emptying of the container is interrupted and the actual material volume is recorded. Using the sensor to be calibrated a distance measurement is implemented and the actual material volume is entered in the evaluation circuit. The evaluation circuit determines on the basis of the memorized relationship between level and material volume the level corresponding to the entered material volume and computes the empty distance as the sum of the level corresponding to the entered material volume and the distance measured by the sensor. In this way calibration is possible at a single calibration point without having to change the level in the container.