TABLE OF CONTENTS This chapter introduces batch processing equipment and the control that is applied to it. Every batch process consists of separate process functions that may be invoked by a recipe as required to make a product. Equipment is required to cause or contain each process function. Control is required to bring uniformity to the process function. It is useful to consider the combination as controlled equipment because the process function cannot be carried out by either component alone.
The different kinds of control were described in the preceding chapter, but little was said about the human component of control. The following section describes different levels of human involvement in control. The decision is made by management, considering the requirements of the process, the capabilities of the people, and the costs. Some managers prefer to replace the uncertainties of people with the predictability that automation systems provide (after the last bug has been removed). There are too many factors governing this decision to consider in this book, beyond describing the levels.
The distinction between automatic and automated control, as used in this book, is that automatic control aids the operator while automation replaces the operator with a programmed machine. There are people who define automation as the addition of automatic controls to a process. This was true when automatic remote control was new. Now the cost of automation is always partly justified by the reduction in the number of operators, as...
