TABLE OF CONTENTS Physical models are used to describe the physical assets of an enterprise and the hierarchical relationships among the various assets involved in batch manufacturing. Usually, physical assets are organized in a hierarchical structure. Physical model provides a means to organize and define the equipment used to control the batch process. The physical model has seven hierarchical levels, starting from 'Enterprise' at the apex to 'Control modules' at the bottom of the hierarchy. A typical hierarchical structure of a physical model is shown in Figure 2.1. The S88 standard scope covers the bottom four levels of the physical model, as shown in Figure 2.1. The top three levels, namely, enterprise, site and area are not addressed by the ISA S88 standard. A brief description of these levels is as follows.
Enterprise defines the company that owns the plant or manufacturing facility.
Site defines the location of the plant or manufacturing facility. The enterprise and the site levels provide a link to business systems and regulatory compliance requirements.
Area defines a specific section of the site. The area contains one or more process cells.
In a physical model, the bottom four levels are specific to the types of equipment. Higher level consists of groups of lower levels in the hierarchy.
Hierarchy levels are defined by engineering activities. During the engineering activity, to simplify the operation of an equipment, all the equipments at the lower levels are grouped...
