• The analyser should not be affected by hydraulic
or mechanical "noise". Most analysers use
frequency / vibration techniques for analysis.
• The trimming stream should be selected by the
stream with the most effect on the blended
product.
• The accuracy of the trim is dictated by the
accuracy of the analyser. Great care must be used
in selecting the right analyser for the job.
To maintain quality, the effect of analyser trim and
the possibilities of stream starvation must be
considered. This phenomenon often occurs during
blending when one or both of the component tanks
are stratified. It is normal to allow a small drift in trim
adjustment before raising an alarm and/or reverting
to ratio control or shutting down.
Recent developments in Jiskoot blending control
systems have included dual trim control that allows
two different analysers such as viscosity and density
to be installed on the same blender. The blending
control system has a hierarchy of control that
eliminates the obvious problems of the analysers
fighting each other. This is particularly useful for
suppliers who tightly control more than one
parameter such as sulphur content.