20130219986 | METHOD AND APPARATUS FOR CALIBRATING A FLOW METER - In the method for calibrating a flow meter, at least two acoustic sensors are arranged at a distance to each other on a straight measuring portion, and a tracer is fed into the fluid flowing in the process pipe at a set mixing distance from the first measuring point. The momentary reference value of the flow velocity of the flowing fluid is measured by determining the travel time of the acoustic tracer between at least two sensors on the same straight measuring portion, by using the acoustic sensors to detect the relative content response of the tracer. This measured value can be compared with the value displayed by the flow meter. The mixing distance of the tracer is arranged to be at least long enough for the tracer to have effectively mixed at the first measuring point over the entire cross-section of the flow path of the fluid. | 08-29-2013 |