When should a sampling take place; and should the online measurements be used on a continuous basis or as
summarized value over a certain time?
• Where should a sampling take place; and where should an online device be located?
• How should a sampling or measurement be arranged? A second question in relation to “How” are the way
and the model of online instrument information used in an active process control.
• Which are the relevant pollution and operation variables that should be analysed and controlled?
All these four points must be clearly addressed prior to an implementation of either a sampling scheme or the
integration of online instruments in the selected process. In the following these four points are discussed and illustrated
by examples.