The ISA S88 international standard is usually associated with batch-type processes. However, Foxboro has been successful in using object-oriented S88 models and terminology (Control Modules, Phases, Units, etc.) for sequential phase logic control in selected continuous-type processes, such as spray dryers. Here, frequent product changes and the necessary process start ups and shut downs must be handled orderly and efficiently. At Universal Flavors, each product change also requires a CIP cycle, which adds additional sequencing requirements.
"Foxboro's S88 approach and phase sequencing software makes the system easier to use and more bulletproof by forcing operators to perform a sequenced start up," says Norman Voigt, process manager, who oversees process control for Universal Flavors. "I especially like the way their solution maps very smoothly over the S88 model.