ABSTRACT
The oldest and simplest methods of flow measurement are the various tagging techniques. Here a portion of the flowstream is tagged at some upstream point and the flow rate is determined as a measurement of transit time. Variations of this technique include particle tracking, pulse tracking, dye or chemical tracing, including the radioactive types. When fully developed, correlation flowmetering can extend the ability to measure flow not only into the most hostile process environments, but also into areas of multiphase flow and into three-dimensional flow vectoring. The following process variables display persistent-enough noise patterns so that correlation flowmeters can be built by using an identical pair of these sensors: density, pressure, temperature, ultrasonics, gamma radiation, capacitive density and conductivity. Several of the above process variables, such as temperature, gamma radiation, and capacitive density have been investigated as potential sensors for correlation flowmeters.
