WHY SHOULD DENSITY BE MEASURED ?
In many industrial processes knowledge about the density is required - be it specific gravity or bulk density - to draw a conclusion on process parameters.
In many instances density is only a measure for other properties: By using density it is possible to determine the concentration of a mix consisting of two materials or the content of solid matter when transported through pipes.
DENSITY CAN BE MEASURED CONTINUOUSLY IN RUNNING PROCESSES.
WHAT ARE THE CAPABILITIES OF RADIOMETRIC DENSITY METERS?
The result of the absorption measurement is influenced by the average density between the detector and the source of radiaton. All those parts which are crossed by the measuring beam and do not change during operation are included in the calibration. Since only the meduim to be measured is subject to change, it is possible to determine exactly the density.
It is important that the average density is used. Thus one can conclude to other properites from this measurement: specific density, concentration of solid matter (i.e. coal, ore, salt) and concentration of mixes (acids, lye, content of sugar).
HOW DOES IT WORK ?
An electromagnetic wave called Gamma radiation with the same properties of X-rays is weakened according to its density by passing through matter . When a fixed intensity is know relating to its density, the ratio to every other density can be calculated according to the intensity it lets pass through. Like an x-ray photograph has its dark parts where the density is higher also the intensity of the Gamma-rays becomes lower with a higher density. A high accurat determination of the intensity therfore is able to determine the density to a point where laboratories sometimes have difficulties to undercut the error. To achieve this only a few components are necessary: The source, installed in a secure lead shielding, further a high sophisticated detector and an evaluation unit.
WHERE CAN MEASUREMENTS BE PERFORMED ?
A constant measuring distance is necessary to determine the density exactly. The simplest way to achieve this is measuring through a pipe. But it is also achievable in a tank or a bunker by a special construction. Contactless measurement is also possible in a container: Neither the source of radiation nor the detector touch the medium.